A comparative study on outcomes of fasting vs postprandial thyroid function tests among pregnant mothers in a tertiary care setting in Sri Lanka

OBJECTIVE

Accurate estimation of serum thyrotropin (TSH) is crucial in the diagnosis of subclinical hypothyroidism (SCH) in pregnancy. We aimed to investigate whether there are significant differences between fasting and nonfasting thyroid function tests (TFTs) among pregnant mothers.

METHODS

We studied 100 pregnant mothers with previously unknown thyroid dysfunction. An equal number of participants were included in each trimester. All pregnant mothers underwent fasting and 2-hour postprandial TFTs (TSH, free T4).

RESULTS

Postprandial TSH (mean 1.01 mIU/L, SD 0.80) was significantly lower than the fasting TSH (mean 1.47 mIU/L, SD 1.18) in pregnancy (P < .01). Postprandial free T4 (mean 10.30 pmol/L, SD 2.01) was also lowered compared with fasting free T4 (mean 10.70 pmol/L, SD 1.99) in pregnancy (P < .01). The prevalence of SCH in pregnancy estimated using fasting TSH was 9.4% (SD 3%). In contrast, the prevalence was only 3.5% (SD 2%) when postprandial TSH was used.

CONCLUSION

Compared with the fasting state, postprandial TSH demonstrates a statistically significant reduction that greatly influences the diagnosis of SCH in pregnant mothers. Therefore, we conclude that the timing of sampling for TFTs should be standardized, especially in the pregnant population.

The Impact of Physical Activity on Thyroid Health: Insights From Representative Data in Korea

CONTEXT

Thyroid hormones are essential for energy metabolism related to thermogenesis and oxygen consumption.

OBJECTIVE

This study evaluated the potential association of thyroid function including thyroid peroxidase antibodies (TPOAb) with physical activity in nationally representative data.

DESIGN/SETTING/PARTICIPANTS

This retrospective cohort study used data from the Korean National Health and Nutrition Examination Survey between 2013 and 2015. Physical activity (PA) was assessed using metabolic equivalents based on the validated Korean version of the International Physical Activity Questionnaire Short Form. PA level was categorized into 3 groups of high, moderate, and low. Participants with abnormal thyroid function test, restricted activity, or previous history of thyroid disease were excluded in the study.

RESULTS

A total of 5372 participants was finally selected. The free T4 level was lowest in the low PA group, while TSH was not significantly different among the groups. TPOAb titers increased in the following order: moderate PA, low PA, and high PA. After adjustment for confounding factors, moderate PA was associated with a high T4 level and a decrease in TSH and TPOAb with significance. However, there were no significant changes in free T4, TSH, or TPOAb titer in the high PA group. In a subanalysis, females with moderate PA showed a significant decrease in TSH and TPOAb. In both males and females, insulin sensitivity was increased with moderate PA. In obese participants, TSH negatively correlated with PA, and free T4 levels decreased in the low PA. The sensitivity to thyroid hormone did not differ in our study.

CONCLUSION

The present study found an association between thyroid function and moderate PA. Therefore, moderate-intensity PA should be recommended to improve thyroid function.

Protective effect of thyroid and restores of ovarian function of Buzhong Yiqi granule on experimental autoimmune thyroiditis in female rats

OBJECTIVE

To observe the effects of Buzhong Yiqi granule on thyroid function and ovarian function in rats with experimental autoimmune thyroiditis (EAT).

METHODS

EAT model was replicate by using the method of mixing and injecting porcine thyroglobulin with Freund's adjuvant and high iodine. Rats were randomly divided into normal control (NC) group, EAT model (EAT) group, selenium yeast (PC) group, low dose Buzhong Yiqi (BZYQ-L) group, medium dose Buzhong Yiqi (BZYQ-M) group and high dose Buzhong Yiqi (BZYQ-H) group. After two months of drug intervention according to dosage, enzyme-linked immunosorbent assay (ELISA) was used to measure the levels of free triiodothyronine (FT3), free thyroxine (FT4), thyroid-stimulating hormone (TSH), anti-thyroid peroxidase antibody (TPOAb), thyroglobulin antibody (TGAb) in peripheral blood of rats. The pathological changes of rat thyroid tissues were observed under light microscope with HE staining; ELISA was used to determine estradiol (E2), follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone (T), anti-müllerian hormone (AMH), and the pathological changes of rat ovarian tissues were observed under light microscope with hematoxylin and eosin staining.

RESULTS

Compared with the NC group, BZYQ granule improved the thyroid and ovarian tissue morphology, and the levels of TPOAb, TGAb and TSH in the model group rats significantly increased (P < 0.05), the thyroid tissue was severely destroyed, the levels of E2, FSH, LH, T, AMH significantly increased (P < 0.05), and the ovary exhibited polycystic changes; Compared with the model group, TSH level in the BZYQ-L group rats decreased (P < 0.05), FSH, T, AMH levels decreased (P < 0.05), in the BZYQ-M group TPOAb, TSH levels decreased (P < 0.05), FSH, LH, T, AMH levels significantly decreased (P < 0.05), BZYQ-H group TPOAb, TGAb, TSH levels significantly decreased (P < 0.05), FSH, LH, T, AMH levels significantly decreased (P < 0.05), with the greatest improvement and significantly better than selenium yeast group (P < 0.05).

CONCLUSIONS

BZYQ granule could regulate the thyroid function of EAT rats, reduce thyroid antibody titers, then act on the ovarian function, regulate hormone disorders, and alleviate the pathological damage of rat's ovarian tissues. The effect of high dose Buzhong Yiqi granule is the best.

Risk Factors for Thyroid Dysfunction in Pregnancy: An Individual Participant Data Meta-Analysis

Background: International guidelines recommend targeted screening to identify gestational thyroid dysfunction. However, currently used risk factors have questionable discriminative ability. We quantified the risk for thyroid function test abnormalities for a subset of risk factors currently used in international guidelines. Methods: We included prospective cohort studies with data on gestational maternal thyroid function and potential risk factors (maternal age, body mass index [BMI], parity, smoking status, pregnancy through in vitro fertilization, twin pregnancy, gestational age, maternal education, and thyroid peroxidase antibody [TPOAb] or thyroglobulin antibody [TgAb] positivity). Exclusion criteria were pre-existing thyroid disease and use of thyroid interfering medication. We analyzed individual participant data using mixed-effects regression models. Primary outcomes were overt and subclinical hypothyroidism and a treatment indication (defined as overt hypothyroidism, subclinical hypothyroidism with thyrotropin >10 mU/L, or subclinical hypothyroidism with TPOAb positivity). Results: The study population comprised 65,559 participants in 25 cohorts. The screening rate in cohorts using risk factors currently recommended (age >30 years, parity ≥2, BMI ≥40) was 58%, with a detection rate for overt and subclinical hypothyroidism of 59%. The absolute risk for overt or subclinical hypothyroidism varied <2% over the full range of age and BMI and for any parity. Receiver operating characteristic curves, fitted using maternal age, BMI, smoking status, parity, and gestational age at blood sampling as explanatory variables, yielded areas under the curve ranging from 0.58 to 0.63 for the primary outcomes. TPOAbs/TgAbs positivity was associated with overt hypothyroidism (approximate risk for antibody negativity 0.1%, isolated TgAb positivity 2.4%, isolated TPOAb positivity 3.8%, combined antibody positivity 7.0%; p < 0.001), subclinical hypothyroidism (risk for antibody negativity 2.2%, isolated TgAb positivity 8.1%, isolated TPOAb positivity 14.2%, combined antibody positivity 20.0%; p < 0.001) and a treatment indication (risk for antibody negativity 0.2%, isolated TgAb positivity 2.2%, isolated TPOAb positivity 3.0%, and combined antibody positivity 5.1%; p < 0.001). Twin pregnancy was associated with a higher risk of overt hyperthyroidism (5.6% vs. 0.7%; p < 0.001). Conclusions: The risk factors assessed in this study had poor predictive ability for detecting thyroid function test abnormalities, questioning their clinical usability for targeted screening. As expected, TPOAb positivity (used as a benchmark) was a relevant risk factor for (subclinical) hypothyroidism. These results provide insights into different risk factors for gestational thyroid dysfunction.

Approach to the Patient With Raised Thyroid Hormones and Nonsuppressed TSH

Measurement of free thyroid hormones (THs) and thyrotropin (TSH) using automated immunoassays is central to the diagnosis of thyroid dysfunction. Using illustrative cases, we describe a diagnostic approach to discordant thyroid function tests, focusing on entities causing elevated free thyroxine and/or free triiodothyronine measurements with nonsuppressed TSH levels. Different types of analytical interference (eg, abnormal thyroid hormone binding proteins, antibodies to iodothyronines or TSH, heterophile antibodies, biotin) or disorders (eg, resistance to thyroid hormone β or α, monocarboxylate transporter 8 or selenoprotein deficiency, TSH-secreting pituitary tumor) that can cause this biochemical pattern will be considered. We show that a structured approach, combining clinical assessment with additional laboratory investigations to exclude assay artifact, followed by genetic testing or specialized imaging, can establish a correct diagnosis, potentially preventing unnecessary investigation or inappropriate therapy.

Effect of Laparoscopic Sleeve Gastrectomy on Thyroid Function Tests and Levothyroxine Doses in People With Obesity

INTRODUCTION

We investigated how laparoscopic sleeve gastrectomy (LSG) affected serum levels of thyroid-stimulating hormone (TSH), free thyroxine (FT4), and free triiodothyronine (FT3) in obese patients with hypothyroidism. We additionally examined whether the dose of levothyroxine decreases as a result of weight loss in this study.

MATERIALS AND METHODS

Fifty-one people with obesity who received levothyroxine treatment for hypothyroidism and underwent LSG between January 2017 and January 2023 were retrospectively examined. Weight, body mass index (BMI), TSH, FT4, FT3, weekly levothyroxine dose changes, and weight-adjusted levothyroxine doses before surgery and the sixth month after surgery were compared.

RESULTS

Among the 51 patients included in this study, 50.98% ceased the use of levothyroxine, and nearly half (41.18%) required an adjustment of their levothyroxine dose during the follow-up period (sixth month). Notably, the total weekly dose of levothyroxine (mcg) decreased in the sixth month following surgery (p<0.001). The weekly weight-adjusted dose (mcg/kg) decreased during the same time frame (p<0.001). The preoperative total weekly dose of levothyroxine, EWL% and absence of hyperlipidemia were found to be the independent predictors of the weight-adjusted weekly levothyroxine dose change (p<0.001, p=0.038, and p=0.044, respectively).

CONCLUSIONS

Thyroid function tests in people with obesity can show improvement after LSG. LSG may reduce the weight-adjusted dose of levothyroxine at six months postoperatively and therefore patients should be monitored for possible levothyroxine dose readjustments based on weight loss.

TSH and FT4 Reference Interval Recommendations and Prevalence of Gestational Thyroid Dysfunction: Quantification of Current Diagnostic Approaches

CONTEXT

Guidelines recommend use of population- and trimester-specific thyroid-stimulating hormone (TSH) and free thyroxine (FT4) reference intervals (RIs) in pregnancy. Since these are often unavailable, clinicians frequently rely on alternative diagnostic strategies. We sought to quantify the diagnostic consequences of current recommendations.

METHODS

We included cohorts participating in the Consortium on Thyroid and Pregnancy. Different approaches were used to define RIs: a TSH fixed upper limit of 4.0 mU/L (fixed limit approach), a fixed subtraction from the upper limit for TSH of 0.5 mU/L (subtraction approach) and using nonpregnancy RIs. Outcome measures were sensitivity and false discovery rate (FDR) of women for whom levothyroxine treatment was indicated and those for whom treatment would be considered according to international guidelines.

RESULTS

The study population comprised 52 496 participants from 18 cohorts. Compared with the use of trimester-specific RIs, alternative approaches had a low sensitivity (0.63-0.82) and high FDR (0.11-0.35) to detect women with a treatment indication or consideration. Sensitivity and FDR to detect a treatment indication in the first trimester were similar between the fixed limit, subtraction, and nonpregnancy approach (0.77-0.11 vs 0.74-0.16 vs 0.60-0.11). The diagnostic performance to detect overt hypothyroidism, isolated hypothyroxinemia, and (sub)clinical hyperthyroidism mainly varied between FT4 RI approaches, while the diagnostic performance to detect subclinical hypothyroidism varied between the applied TSH RI approaches.

CONCLUSION

Alternative approaches to define RIs for TSH and FT4 in pregnancy result in considerable overdiagnosis and underdiagnosis compared with population- and trimester-specific RIs. Additional strategies need to be explored to optimize identification of thyroid dysfunction during pregnancy.

The Combined Effect of Immune Checkpoint Inhibitors and Tyrosine Kinase Inhibitors on Thyroid Function

Background: Recent successes with immune checkpoint inhibitors (ICIs) and tyrosine kinase inhibitors (TKIs) for the treatment of solid malignancies have paved the way for a new era of combined therapy. A common side effect seen with each of these classes of treatment is thyroid dysfunction, with rates estimated at 30-40% for TKI and 10-20% for ICI. However, little is known about the effect of combined ICI+TKI therapy on thyroid function. Therefore, this study evaluated the incidence, clinical features, and risk factors for developing thyroid abnormalities during ICI+TKI therapy and the relationship to cancer outcomes. Methods: We conducted a retrospective cohort study of patients treated with combination ICI+TKI cancer therapy at City of Hope Comprehensive Cancer Center from 2017 to 2023 who had pretreatment normal thyrotropin (TSH) levels. Primary analyses assessed the frequency, timing, and severity of thyroid function test abnormalities during ICI+TKI cancer therapy, and the requirement for thyroid hormone replacement. Secondary analyses evaluated risk factors for the development of thyroid dysfunction, including sex and drug regimen, and the association with cancer progression-free survival or overall survival. Univariable and multivariable models were used. Results: There were 106 patients who received ICI+TKI therapy with a median age of 63.5 years and a median follow-up of 12.8 months (interquartile range [IQR] 5.9-20.9). Notably, 63.2% (67/106) developed thyroid function abnormalities during ICI+TKI therapy, including 11 (10.4%) with hyperthyroidism, 42 (39.6%) with subclinical hypothyroidism (SCHypo), and 14 (13.2%) with overt hypothyroidism. The onset of thyroid dysfunction occurred at a median of 7 weeks (IQR 3.1-9.0) after start of ICI+TKI treatment for hyperthyroidism, 8.0 weeks (IQR 3.0-19.0) for SCHypo, and 8.1 weeks (IQR 5.9-9.1) for overt or worsening hypothyroidism. Hyperthyroidism resolved to hypothyroidism or normal TSH without intervention in all subjects, suggesting thyroiditis, and hypothyroidism was readily treated with thyroid hormone replacement. Conclusions: Thyroid dysfunction is a frequent adverse event in individuals treated with combination ICI+TKI therapy, with our data suggesting a rapid onset and higher incidence than previously seen with ICI or TKI therapy alone. Therefore, close monitoring of thyroid function during initial therapy and multidisciplinary care with endocrinology are recommended to facilitate early detection and initiation of thyroid hormone replacement in these patients.

Updates on thyroid disorders in pregnancy and the postpartum period

ABSTRACT

NPs play a pivotal role in caring for pregnant people. This article provides an overview of gestational and postpartum thyroid disorders, including their assessment, management, and indications for referral. The goal of this article is to help providers better assess and manage thyroid disorders during pregnancy and improve patient outcomes.

Laparoscopic Sleeve Gastrectomy: Impact on Body Mass Index and Thyroid Hormones in Euthyroid Obese Patients

BACKGROUND Obesity is still a major global public health problem and its incidence is increasing. Obesity leads to deterioration in thyroid functions. Even when they are within normal ranges, high normal levels of thyroid-stimulating hormone (TSH) increase morbidity and mortality. This study aimed to evaluate the body mass index (BMI) and TSH levels in 300 euthyroid patients with obesity before and after laparoscopic sleeve gastrectomy (LSG). MATERIAL AND METHODS A total of 300 euthyroid patients who underwent LSG between 2019 and 2021 were included in the study. Body mass index (BMI), thyroid-stimulating hormone (TSH), and free triiodothyronine (FT) 3 and tetraiodothyronine (FT4) levels were recorded before surgery and at 6 and 12 months after surgery and subsequently analyzed. RESULTS Mean BMI values were significantly lower at 6 and 12 months after surgery (P<0.001). There was a significant difference between mean TSH and FT4 levels before surgery and those at 6 and 12 months after surgery (P<0.001). However, mean FT3 levels remained unchanged 1 year after surgery (P=0.005). CONCLUSIONS LSG is not only effective in terms of weight loss, but also exhibits improving effects on thyroid hormone homeostasis in obese patients and provides protection against further adverse effects of TSH.

Thyroid function, renal function, and depression: an association study

Objective

To investigate the correlations between thyroid function, renal function, and depression.

Methods

Clinical data of 67 patients with Major depressive disorder (MDD) and 36 healthy control subjects between 2018 and 2021 were collected to compare thyroid and renal function. Thyroid and renal functions of depressed patients were then correlated with the Hamilton Depression Rating Scale (HAMD) and the Hamilton Anxiety Rating Scale (HAMA).Spearman correlation analysis was used to find the correlation between renal function, thyroid function, and depression. A logistic regression was performed to find significant predictors of depression.

Results

Triiodothyronine protamine (T3), thyroxine (T4), free triiodothyronine protamine (FT3), uric acid, sodium, and anion gap were lower in the MDD group than in the control group (p < 0.05). Correlation analysis of thyroid function, renal function, and factor terms of HAMD in the MDD group suggested that diurnal variation, hopelessness, and depression level were positively correlated with thyrotropin (TSH) (p < 0.05). Cognitive disturbance, retardation, and depression level were negatively correlated with creatinine (p < 0.05). Diurnal variation was negatively correlated with sodium ion (p < 0.01); hopelessness and depression level were positively correlated with chloride ion (p < 0.05); diurnal variation, retardation, and depression level were negatively correlated with anion gap (p < 0.05). Diurnal variation (p < 0.01) and retardation (p < 0.05) were negatively correlated with osmolality. Cognitive disturbance and depression level were positively correlated with estimated glomerular filtration rate (eGFR) (p < 0.05). In the MDD group, correlation analysis of thyroid function, renal function, and HAMA factor terms suggested that the total HAMA score and anxiety level were positively correlated with chloride ion (p < 0.05); psychic anxiety, total HAMA score, and anxiety level were negatively correlated with anion gap (p < 0.05). Furthermore, a low level of anion gap was an independent risk factor for depression and anxiety levels (p < 0.05).

Conclusion

Low thyroid function and reduced waste metabolized by the kidneys in patients with MDD suggest a low intake and low metabolism in depressed patients. In addition, subtle fluctuations in the anion gap in depressed patients were strongly correlated with the degree of depression and anxiety.

Thyroid Function Tests in Children and Adolescents With Trisomy 21: Definition of Syndrome-Specific Reference Ranges

CONTEXT

The lack of syndrome-specific reference ranges for thyroid function tests (TFT) among pediatric patients with Down syndrome (DS) results in an overestimation of the occurrence of hypothyroidism in this population.

OBJECTIVE

To (a) outline the age-dependent distribution of TFT among pediatric patients with DS; (b) describe the intraindividual variability of TFT over time; and (c) assess the role of elevated thyrotropin (TSH) in predicting the future onset of overt hypothyroidism.

METHODS

In this retrospective, monocentric, observational analysis, we included 548 patients with DS (0-18 years) longitudinally assessed between 1992 and 2022. Exclusion criteria were abnormal thyroid anatomy, treatments affecting TFT, and positive thyroid autoantibodies.

RESULTS

We determined the age-dependent distribution of TSH, FT3, and FT4 and outlined the relative nomograms for children with DS. Compared with non-syndromic patients, median TSH levels were statistically greater at any age (P < .001). Median FT3 and FT4 levels were statistically lower than controls (P < .001) only in specific age classes (0-11 for FT3, 11-18 years for FT4). TSH levels showed a remarkable fluctuation over time, with a poor (23%-53%) agreement between the TSH centile classes at 2 sequential assessments. Finally, the 75th centile was the threshold above which TSH values predicted future evolution into overt hypothyroidism with the best statistical accuracy, with a satisfactory negative predictive value (0.91), but poor positive predictive value (0.15).

CONCLUSION

By longitudinally assessing TFT in a wide pediatric DS population, we outlined the syndrome-specific reference nomograms for TSH, FT3, and FT4 and demonstrated a persistent upward shift of TSH compared to non-syndromic children.

Thyroid function test variability and cardiovascular morbidity in hyperthyroidism

OBJECTIVE

The variability of thyroid function tests (TFTs) during antithyroid drug (ATD) therapy and its association with adverse health outcomes have not been previously studied. The aim of this study was to evaluate the association of TFT variability and cardiovascular morbidity during ATD therapy.

DESIGN

Retrospective cohort study.

PATIENTS AND MEASUREMENTS

Hyperthyroid patients (n = 394) treated with ATD therapy at Tampere University Hospital between March 2016 and December 2018 were followed up for a median time of 1.5 years (interquartile range 0.8-2.0). The coefficients of variation (CVs) of the follow-up thyroid-stimulating hormone (TSH), free thyroxine (fT4) and free triiodothyronine (fT3) measurements were determined. The associations of TFT variability and baseline clinical factors with cardiovascular disease (CVD) -associated hospital visits were assessed with logistic regression analyses.

RESULTS

In the multivariable analyses, age (odds ratio [OR]: 1.06, 95% confidence interval [CI]: 1.03-1.09), male gender (OR: 2.33, 95% CI: 1.03-5.28) and fT4-CV (OR: 1.02, 95% CI: 1.01-1.04) were independent risk factors for cardiovascular morbidity, whereas baseline positive thyrotropin receptor antibodies (TRAbs) were associated with lower cardiovascular morbidity (OR: 0.29, 95% CI: 0.14-0.61). When the patients with baseline TRAb positivity were studied separately, fT4-CV was associated with cardiovascular morbidity (OR: 1.03, 95% CI: 1.00-1.05).

CONCLUSIONS

During ATD therapy, fT4 variability is associated with an increased cardiovascular morbidity. Although positive TRAbs are associated with a lower cardiovascular morbidity compared with hyperthyroidism with negative autoantibodies, the variability of fT4 is associated with cardiovascular morbidity also in patients with positive TRAbs.

The Effects of Thyroid Hormone Levels on Patent Ductus Arteriosus Closure in Newborns

Objective

Although the role of thyroid hormones in functional and anatomical closure of patent ductus arteriosus (PDA) is well known, their effects on the medical or surgical closure of PDA in newborns remain unclear. This study aimed to assess the correlation between thyroid function tests and PDA closure through medical or surgical interventions in newborns.

Methods

This retrospective study was conducted on 65 newborns diagnosed with hemodynamically significant PDA (hs-PDA), with a premature rate of 81.5% (n=53). The subjects were divided into two groups according to the nature of the ductal closure as medically responsive "MR-PDA" or surgically treated "ST-PDA". The groups were compared in terms of thyroid hormone levels and other clinical parameters.

Results

Thirty-three (51%) of all 65 patients had PDA and responded to medical treatment. Gestational week, birth weight, and mode of delivery were similar between the medical and surgical treatment groups (p>0.05). Free thyroxine levels were significantly lower in the MR-PDA group than in the ST-PDA group (p=0.01).

Conclusions

Because hs-PDA is associated with increased morbidity and mortality in the neonatal period, especially in premature infants, we hypothesize that thyroid hormone levels may play a role in the closure of hs-PDA.

Characteristics and response cutoff of Octreotide Suppression Test in Thyrotropin (TSH)-secreting pituitary adenomas

CONTEXT

Somatostatin analogs are recommended for preoperative therapy in Thyrotropin secreting pituitary adenomas (TSHomas). Octreotide suppression test (OST) was designed to differentiate TSHomas with Resistance to Thyroid Hormones, while its ability to test sensitivity of SSA has not be fully studied.

OBJECTIVE

To test the sensitivity of SSA in TSHomas with OST.

PATIENTS

We collected 48 pathologically confirmed TSHoma patients with complete 72 hours' data of OST into analysis.

INTERVENTION

Octreotide suppression test MAIN OUTCOME: Sensitivity timepoint and cutoff of OST RESULTS: During the entire OST, the TSH descended maximally 89.07% (73.85%,96.77%), while the FT3 and FT4 declined slowly [43.40% (37.80%,54.44%) and 26.59% (19.01%,33.13%), respectively]. The 24^th hour was the timepoint wherein the stability occurs for TSH and the 48^th hour for FT3 and FT4 during OST. In the patients who received both short- and long-acting Somatostatin analogs (SSA), the 24-hour timepoint was the most predictive timepoint for the percentage of TSH decline (Spearman's rank correlation analysis, r=0.571, p<0.001), while the 72-hour timepoint was optimal for predicting the magnitude of TSH decline (Spearman's rank correlation analysis, r=0.438, p=0.005). In the 24^th timepoint, a positive correlation was also observed between TSH suppression rate and the percentage decrease and absolute value decrease of FT3 and FT4. Furthermore, in patients treated with long-acting SSA, the 72-hour timepoint was optimal for predicting both the percentage (Spearman's rank correlation analysis, r=0.587, p=0.01) and magnitude (Spearman's rank correlation analysis, r=0.474, p=0.047) of TSH decline. The 24^th hour was the optimal timepoint with 44.54% (50% of median value of TSH in 72hOST) decrease of TSH being the observing cutoff. The adverse effect of OST was predominantly occurred in gastrointestinal system and no severe event occurred during OST. Paradoxical response could occur in OST and it did not influence the effect of SSA as long as sensitivity was confirmed. High level of hormonal control was achieved in the SSA-sensitive patients.

CONCLUSION

OST can be used as efficient tool to guide the adequate use of SSA. This article is protected by copyright. All rights reserved.

Effect of Inactivated and mRNA COVID-19 Vaccination on Thyroid Function Among Patients Treated for Hyperthyroidism

CONTEXT

Reports of thyroid dysfunction following COVID-19 vaccination included cases of relapse of Graves' disease and worsening of pre-existing Graves' disease. Little is known about the thyroid-specific outcomes among patients treated for hyperthyroidism who have received COVID-19 vaccination.

OBJECTIVE

Among patients treated for hyperthyroidism, we evaluated factors associated with not receiving the COVID-19 vaccination and whether COVID-19 vaccination was associated with thyroid function instability.

METHODS

We included consecutive patients treated for hyperthyroidism attending the thyroid clinic at a teaching hospital between January and September 2021. They were categorized into vaccinated and unvaccinated groups. The index date was the date of first-dose vaccination for the vaccinated group, and the first date of attendance in the inclusion period for the unvaccinated group. They were followed up until March 2022 or occurrence of thyroid function instability (worsening of thyroid function/increase in antithyroid drug dosage), whichever was earlier.

RESULTS

A total of 910 patients were included (mean age 51.6 years; 82.1% female). Of these, 86.2% had Graves disease and 67.3% were vaccinated (67.3% BNT162b2; 30.6% CoronaVac; 2.1% heterologous). Abnormal thyroid function and cardiovascular comorbidities were independently associated with unvaccinated status. Upon median follow-up of 5.3 months, thyroid function instability occurred in 15.9% of patients. COVID-19 vaccination did not increase risks of thyroid function instability (hazard ratio 0.78, 95% CI 0.56-1.09, P = .151); this was consistent in Graves disease, both types of vaccines, and regardless of whether baseline thyroid function was normal. Twenty-seven patients overtly thyrotoxic at the time of vaccination received COVID-19 vaccines without triggering a thyroid storm or difficulty in subsequent thyroid function control.

CONCLUSION

Among patients treated for hyperthyroidism, abnormal thyroid function was a factor predicting unvaccinated status. Our results should encourage patients treated for hyperthyroidism to receive COVID-19 vaccination to protect themselves from adverse outcomes and potential long-term sequelae of COVID-19.

Thyroid Function in Neonates with Hypoxic Ischemic Encephalopathy

We aimed to examine heel prick (capillary) and serum thyroid function test (TFT) results in neonates with hypoxic ischemic encephalopathy (HIE) to evaluate the effect of asphyxia and therapeutic hypothermia (TH) on thyroid functions. This retrospective chart review included infants who were born after 34 weeks of gestation, were diagnosed and treated for HIE. The patients were divided into those who did and did not undergo TH and the groups were compared in terms of demographic characteristics, laboratory results, capillary thyroid-stimulating hormone (cTSH) levels, and serum thyroid-stimulating hormone (TSH) and free thyroxine (fT4) levels. A total of 111 neonates were included in the study. There was no difference between the TH group (n = 90) and the nonhypothermia group (n = 21) in terms of median gestational age (38.3 ± 2.1 weeks vs. 38.6 ± 1.8 weeks, p = 0.42) or birth weight (3182 ± 509 g vs. 3174 ± 573 g, p = 0.72). Serum TFT was performed at a median of 10 days (range, 2-43) and capillary TSH analyzed at a median of 6 days (range, 1-26). Capillary TSH at 96 hours was analyzed in 36 patients in the TH group and 19 patients in the nonhypothermia group. Serum TSH and fT4 levels were similar in both groups (p = 0.29, p = 0.1). Overall cTSH and cTSH obtained in the first 4 days were 2.2 (0.5-10) and 4.3 (0.5-94), p = 0.059; 2 (0.5-22) and 5 (0.5-94), p = 0.04, respectively, whereas cTSH obtained after day 4 was similar in both groups (p = 0.058). Abnormal serum TSH (>5.5 mU/mL) was more frequent in the hypothermia group (44.4% vs. 19%, p = 0.026). Our results suggest that TH may cause some alterations on TFTs. Therefore, it may be reasonable to repeat TSH screening after TH.

Thyroidal Angiotensin-Converting Enzyme 2 Protein Expression and Thyroid Function Tests in Patients with COVID-19: Results from a Retrospective Case Series and a Prospective Cohort Study

Background: Infection with SARS-CoV-2 has initially been known as a respiratory disease but in the course of the pandemic the understanding has emerged that severity is owing to fatal inflammatory responses apart from lung injury. In this context, endocrine disorders such as thyroiditis as well as pituitary dysfunction in addition to nonthyroidal illness syndrome have been described. Furthermore, angiotensin-converting enzyme 2 (ACE2), the SARS-CoV-2 cell receptor, has been detected in most endocrine tissues, including the thyroid gland. Objective: To evaluate histopathologic changes and compare thyroidal ACE2 protein expression in thyroid tissue from patients who died from severe COVID-19 with thyroid tissue from patients without SARS-CoV-2 infection in a retrospective case series. Furthermore, to assess and compare alterations in thyroid function tests (TFTs) between patients with or without SARS-CoV-2 infection as well as association of TFTs with the severity of the disease in a prospective cohort study. Methods: Thyroid tissue of deceased COVID-19 patients (n = 23) was analyzed for histopathology and ACE2 expression by immunohistochemical staining. A total of 153 patients with confirmed SARS-CoV-2 were evaluated regarding TFTs and divided into a severe (intubation, intensive care treatment) and an intermediate group. Results: Thyroidal ACE2 expression was detected in 87% of the deceased COVID-19 patients. Normal thyroid tissue from patients without SARS-CoV-2 infection showed no ACE2 protein expression. Half of the severely ill COVID-19 patients had low free triiodothyronine (fT3) levels. Combination of low fT3 and thyrotropin (TSH) was associated significantly with deadly disease. Conclusion: The high percentage of positive ACE2 immunostaining in deceased patients compared with normal thyroid tissue of patients without SARS-CoV-2 infection suggests involvement of the thyroid in COVID-19, although further research will have to show the pathogenic role of thyroidal ACE2 in COVID-19. Abnormal fT3 and a TSH of ≤0.5 mU/L were associated with a fatal outcome in our severely ill SARS-CoV-2 patient cohort. Therefore, assessment of TFTs is crucial in the treatment of severely ill COVID-19 patients. Trial Registration: COVID-19 Registry of the LMU University Hospital Munich (CORKUM), WHO trial ID DRKS00021225.

A prospective follow-up on thyroid function, thyroid autoimmunity and long COVID among 250 COVID-19 survivors

PURPOSE

We evaluated the evolution of thyroid function and autoimmunity among COVID-19 survivors over 6 months in relation to interferon beta-1b treatment and long COVID.

METHODS

We included COVID-19 survivors managed in a major COVID-19 centre between July 2020 and May 2021 who were reassessed three and/or six months after acute COVID-19. Thyroid function tests (TFTs) and anti-thyroid antibody titres were measured at acute COVID-19, 3-month and 6-month.

RESULTS

250 COVID-19 survivors were included (mean age 52.7 years, 50.4% men). Persistent thyroid function abnormalities were more likely in those with abnormal TFTs in acute COVID-19 (P < 0.001). Among 51 patients with abnormal TFTs in acute COVID-19, 82.4% resolved upon follow-up. Of 199 patients with normal TFTs in acute COVID-19, only 4.5% had incident abnormal TFTs, more likely in interferon-treated patients (P = 0.044) and none clinically overt. Among 129 patients with complete 6-month follow-up for anti-thyroid antibody titres, there was no significant change overall, except for modest increase in anti-thyroid antibody titres among the 84 interferon-treated patients (P < 0.05 at both 3 months and 6 months). Long COVID occurred in 19.5% and 10.4% at 3 and 6 months respectively, where TFTs and anti-thyroid antibody titres were not predictive of its occurrence.

CONCLUSION

Over 6 months, most abnormal TFTs in acute COVID-19 resolved, with no significant incident thyroid dysfunction. SARS-CoV-2 infection did not lead to change in thyroid autoimmunity, while interferon treatment was associated with modest increase in anti-thyroid antibody titres. Thyroid function and anti-thyroid antibodies did not play a significant role in long COVID.

What is thyroid function in your just-diagnosed cancer patient?

The principal hormonal product of the thyroid gland, L-thyroxine (T4), is a prohormone for 3,3',5-triiodo-L-thyronine, T3, the major ligand of nuclear thyroid hormone receptors (TRs). At a cell surface thyroid hormone analogue receptor on cancer cell and endothelial cell plasma membrane integrin αvβ3, however, T4 at physiological concentrations is biologically active and is the major ligand. At this site in solid tumor cells, T4 nongenomically initiates cell proliferation, is anti-apoptotic by multiple mechanisms, supports radioresistance and enhances cancer-related angiogenesis. In contrast, hypothyroidism has been reported clinically to slow tumor growth. At physiological levels, T3 is not biologically active at the integrin and maintenance of euthyroidism with T3 in cancer patients may be associated with slowed tumor proliferation. Against this background, we raise the possibility that host serum T4 levels that are spontaneously in the upper tertile or quartile of the normal range in cancer patients may be a factor that contributes to aggressive tumor behavior. Recent observations on tumor metastasis and tumor-associated propensity for thrombosis due to T4 also justify clinical statistical analysis for a relationship to upper tertile hormone levels. That reverse T3 (rT3) may stimulate tumor growth has recently been reported and thus the utility of adding this measurement to thyroid function testing in cancer patients requires assessment. In summary, T4 at physiological concentrations promotes tumor cell division and aggressiveness and euthyroid hypothyroxinemia arrests clinically advanced solid tumors. These findings support the clinical possibility that T4 levels in the upper tertile of the normal range require examination as a tumor supporting factor.

Assesment of attainment of recommended TSH levels and levothyroxine compliance in differentiated thyroid cancer patients

OBJECTIVE

Thyroid-stimulating hormone (TSH) suppression treatment can induce signs and symptoms of hyperthyroidism and hypothyroidism due to inappropriate treatment or poor compliance to the treatment. The current study aimed to investigate TSH levels, frequency of being on target TSH, adherence to levothyroxine (LT4) suppression treatment in differentiated thyroid cancer (DTC) patients after surgery in a multicentric setting.

DESIGN AND PATIENTS

This multicentric cross-sectional study was conducted at 21 medical centres from 12 cities in Turkey. DTC patients followed at least one year in the same center included in the study. Clinical data, serum TSH, free thyroxine (FT4), thyroglobulin (Tg) and anti-Tg levels were recorded during the most recent visit. Body mass index, systolic and diastolic blood pressures, pulse rate were measured. LT4 doses were recorded and doses per kilogram of bodyweight were calculated. Pill ingestion habits recorded and adherence to the therapy were evaluated using the Morisky Medication Adherence Scale and categorized as good, moderate or poor compliant based on their scores. Risk stratification forpredicting the disease persistance and/or reccurence was assessed using the American Joint Committee on Cancer-7th edition thyroid cancer staging calculator. TSH serum concentrations were classified as severe suppression (TSH &lt; 0.01 mU/L), moderate suppression (TSH: 0.01-0.1 mU/L), mild suppression (TSHL 0.1-0.5 mU/L), euthyroid (TSH: 0.5-4 mU/L) and hypothyroid (TSH &gt; 4 mU/L). TSH levels can also be classified as on being on target, under the target, or beyond over the target, according to the American Thyroid Association recommendations.

RESULTS

A group of 1125 patients (F/M: 941/184, 50.7 ± 11.7 years) were included in the study. The mean LT4 daily dosage was 132.4 ± 39.6 mcg/day. TSH levels showed severe suppression in 99 (%8.8) patients, moderate suppression in 277 (%24.6) patients and mild suppression in 315 (%28) patients and euthyroid range in 332 (%29.5) patients and hypothyroid range in 97 (8.6%). TSH levels were in target in 29.2% of the patients 20.4% of the patients were undertreated, 50.4% overtreated. The daily LT4 dose and LT4 dose/kg were significantly higher in the severe suppression group (p &lt; .001, p &lt; .001). According to the Morisky scale, 564 patients (50.1%) were good compliant, 368 patients (32.7%) were moderate compliant, and 193 patients (17.1%) were noncompliant. Patients with poor compliance need a higher dose of LT4 compared to the good compliance group (p &lt; .001). TSH levels of patients with good compliance were 0.67 ± 1.96 mU/L and TSH with poor compliance was 2.74 ± 7.47 mU/L (p &lt; .001). TSH levels were similar in patients on fixed and alternating dosages.

CONCLUSION

In 29.2% of the DTC patients, serum TSH levels were at target levels. Remaining of the study group have TSH levels under or over treatment range, exposing the patient to medication side effects. Majorty of the study group 82.8% have good or moderate adherence to LT4 therapy. Reaching TSH targets requires simplified and applicable guidelines and following the guideline recommendations.

Assessment of thyroid function tests in patients with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD), a group of diseases of distinct aetio-pathological consideration with different phenotypic presentations where smoking is the leading cause, all share the ultimate result of airflow limitation. This study aimed to evaluate thyroid function tests (TFT) in patients with COPD. Pulmonary function tests (PFT) were performed for 30 patients with obstructive lung disease and fifteen healthy control individuals. We measured SPO₂ to confirm COPD and assess the severity of the disease and assessed TT3, TT4, and TSH using the ELISA test. The values of VC, FVC, and FEV in the first second and PEF, TSH, and SPO₂ were lower in the COPD group than in the control group (P-value=0.001). In severe COPD (FEV₁<50%), there was a significant reduction in T3 but not T4 or TSH compared to mild-moderate COPD patients. Thyroid dysfunction was observed in patients with COPD pointing to a metabolic response; patients with lower weight indices had a lower TSH and, consequently, T3.

Effect of COVID-19 Vaccines on Thyroid Function and Autoimmunity and Effect of Thyroid Autoimmunity on Antibody Response

CONTEXT

There are concerns for COVID-19 vaccination in triggering thyroid autoimmunity and causing thyroid dysfunction. Also, data on the effect of preexisting thyroid autoimmunity on the efficacy of COVID-19 vaccination are limited.

OBJECTIVES

We evaluated the effect of COVID-19 vaccination on thyroid function and antibodies, and the influence of preexisting thyroid autoimmunity on neutralizing antibody (NAb) responses.

METHODS

Adults without a history of COVID-19/thyroid disorders who received the COVID-19 vaccination during June to August 2021 were recruited. All received 2 doses of vaccines. Thyrotropin (TSH), free thyroxine (fT4), free 3,5,3'-triiodothyronine (fT3), antithyroid peroxidase (anti-TPO), and antithyroglobulin (anti-Tg) antibodies were measured at baseline and 8 weeks post vaccination. NAb against SARS-CoV-2 receptor-binding domain was measured.

RESULTS

A total of 215 individuals were included (129 [60%] BNT162b2; 86 [40%] CoronaVac recipients): mean age 49.6 years, 37.2% men, and 12.1% anti-TPO/Tg positive at baseline. After vaccination, TSH did not change (P = .225), but fT4 slightly increased (from 12.0 ± 1.1 to 12.2 ± 1.2 pmol/L [from 0.93 ± 0.09 to 0.95 ± 0.09 ng/dL], P < .001) and fT3 slightly decreased (from 4.1 ± 0.4 to 4.0 ± 0.4 pmol/L [from 2.67 ± 0.26 to 2.60 ± 0.26 pg/mL], P < .001). Only 3 patients (1.4%) had abnormal thyroid function post vaccination, none clinically overt. Anti-TPO and anti-Tg titers increased modestly after vaccination (P < .001), without statistically significant changes in anti-TPO/Tg positivity. Changes in thyroid function and antithyroid antibodies were consistent between BNT162b2 and CoronaVac recipients, except for greater anti-TPO titer increase post BNT162b2 (P < .001). NAb responses were similar between individuals with and without preexisting thyroid autoimmunity (P = .855).

CONCLUSION

COVID-19 vaccination was associated with a modest increase in antithyroid antibody titers. Anti-TPO increase was greater among BNT162b2 recipients. However, there was no clinically significant thyroid dysfunction post vaccination. NAb responses were not influenced by preexisting thyroid autoimmunity. Our results provide important reassurance for people to receive the COVID-19 vaccination.

Further understanding of thyroid function in pregnant women

INTRODUCTION

Normal thyroid status throughout pregnancy is important for both maternal and fetal health. Despite the bulk of contemporary research honing on thyroid function in gestation and the relevant disorders, there are still gaps in our current knowledge about the etiology and treatment of thyroid diseases in pregnant women.

AREAS COVERED

This article analyzes the adaptation of the thyroid gland to gestational physiological changes and attempts to explain the effect of several factors on thyroid function in pregnancy. It also stresses proper utilization and interpretation of thyroid tests during pregnancy and underlines the significance of proper screening and treatment of pregnant women aiming at favorable health outcomes.

EXPERT OPINION

Appropriate strategies for diagnosing and treating thyroid disease in pregnancy are important. Laboratory thyroid testing plays a leading role, but test results should be interpreted with caution. Given the possible serious maternal and fetal/neonatal complications of thyroid disease in pregnancy, we recommend universal screening with TSH measurements of all pregnant women. Additional assessment with determination of the levels of free thyroid hormones and thyroid antibodies may be necessary under certain conditions. The economic burden of such interventions should be considered.

Thyroid function tests, incongruent internally and with thyroid status, both in a pregnant woman and in her newborn daughter

Introduction

Thyroid function tests (TFT) are extensively used in daily clinical practice. Here, we described a case of incongruent TFT both in a pregnant woman and in her newborn.

Case presentation

A 32-year-old woman, diagnosed with autoimmune thyroiditis during her first pregnancy, was monitored during her second gestation. At week 5 + 2 days, thyroid-stimulating hormone (TSH) and free thyroxine (FT4) values (Dimension VISTA 1500, Siemens Healthineers) were within normal limits. At week 19 + 5 days, TSH remained normal while FT4 increased approximately by three-fold. FT4 inconsistency was with both TSH and the clinical status since she continued to be clinically euthyroid. On the same serum sample, thyroid autoantibodies were negative. At week 25 + 4 days, the patient complained of palpitations and dyspnea, with tachycardia. Even though TSH was normal, high levels of both FT4 and free triiodothyronine (FT3) were interpreted as evidence of thyroid overactivity and methimazole was started. TFT of the pregnant woman continued to be monitored throughout gestation. Postpartum FT4 and FT3 gradually returned to normal. TFT, performed on the daughter's serum, 3 days after birth, showed the same inconsistency as her mother but without clinical signs of congenital hyperthyroidism. Based on the clinical and laboratory setting, the presence of circulating autoantibodies against T3 and T4 (THAb) was suspected and demonstrated by radioimmunoprecipitation.

Conclusion

Analytical interferences should be supposed when TFT do not fit with the clinical picture and despite their infrequency, THAb must also be considered. To our knowledge, this is the first case describing the passage of THAb to the newborn.

The Independent Association of TSH and Free Triiodothyronine Levels With Lymphocyte Counts Among COVID-19 Patients

Background

Both lymphopenia and thyroid dysfunction are commonly observed among COVID-19 patients. Whether thyroid function independently correlates with lymphocyte counts (LYM) remains to be elucidated.

Methods

We included consecutive adults without known thyroid disorder admitted to Queen Mary Hospital for COVID-19 from July 2020 to April 2021 who had thyroid-stimulating hormone (TSH), free thyroxine (fT4), free triiodothyronine (fT3) and LYM measured on admission.

Results

A total of 541 patients were included. Median LYM was 1.22 x 109/L, with 36.0% of the cohort lymphopenic. 83 patients (15.4%) had abnormal thyroid function tests (TFTs), mostly non-thyroidal illness syndrome (NTIS). Patients with lymphopenia had lower TSH, fT4 and fT3 levels than those without. Multivariable stepwise linear regression analysis revealed that both TSH (standardized beta 0.160, p<0.001) and fT3 (standardized beta 0.094, p=0.023), but not fT4, remained independently correlated with LYM, in addition to age, SARS-CoV-2 viral load, C-reactive protein levels, coagulation profile, sodium levels and more severe clinical presentations. Among the 40 patients who had reassessment of TFTs and LYM after discharge, at a median of 9 days from admission, there were significant increases in TSH (p=0.031), fT3 (p<0.001) and LYM (p<0.001). Furthermore, patients who had both lymphopenia and NTIS were more likely to deteriorate compared to those who only had either one alone, and those without lymphopenia or NTIS (p for trend <0.001).

Conclusion

TSH and fT3 levels showed independent positive correlations with LYM among COVID-19 patients, supporting the interaction between the hypothalamic-pituitary-thyroid axis and immune system in COVID-19.

Associations of Thyroid Function Tests with Lipid Levels and Adverse Pregnancy Outcomes During the First Trimester

OBJECTIVE

The present study aims to evaluate the relationship of thyroid function during the first trimester of pregnancy with lipid levels and pregnancy outcomes.

METHODS

Women who delivered babies at the Shanghai General Hospital between March 2019 and December 2019 with a known pregnancy outcome and complete data were included in the present study (n = 1779). A retrospective cohort study of all subjects with available first-trimester thyroid function testing and lipid levels data was conducted, and the relationship of thyroid function with lipid levels and pregnancy outcomes was evaluated. The data were analyzed using the SPSS software for statistical correlation.

RESULTS

The proportion of caesarean sections was higher in women with hypothyroxinemia (HIA) and hypothyroidism than in women with euthyroidism. Hypothyroidism was shown to be related with polyhydramnios, preterm labor and hypertriglyceridemia. HIA was correlated with increased rates of gestational diabetes mellitus (GDM), preeclampsia, gestational hypertension and hypertriglyceridemia. Compared with the euthyroidism group, the hypothyroidism group had a higher apolipoprotein A1 (Apo A1) level and apolipoprotein B level; the subclinical hypothyroidism group had a higher total cholesterol (TC) level and low-density lipoprotein cholesterol level; the HIA group had higher triglyceride, high-density lipoprotein cholesterol levels and lower TC, Apo A1 levels. TC levels were positively correlated with the thyroid-stimulating hormone level and negatively correlated with free thyroxine (FT4) level, and free triiodothyronine and FT4 levels were positively correlated with GDM occurrence.

CONCLUSION

Thyroid function in early pregnancy is associated with dyslipidemia and pregnancy outcomes; conventional screening of thyroid diseases in early pregnancy may help improve lipid levels and decrease adverse pregnancy outcomes.

Increased Central and Peripheral Thyroid Resistance Indices During the First Half of Gestation Were Associated With Lowered Risk of Gestational Diabetes-Analyses Based on Huizhou Birth Cohort in South China

OBJECTIVES

The study aimed to explore the relationship of thyroid function and resistance indices with subsequent risk of gestational diabetes (GDM).

DESIGN

This was a longitudinal study embedded in the Huizhou Birth Cohort.

METHODS

A total of 2,927 women of singleton pregnancy were recruited from January to October of 2019. Thyroid central resistance indices were evaluated by Thyroid Feedback Quartile-Based index (TFQI), Thyrotrophy T4 Resistance Index (TT4RI), and TSH Index (TSHI) based on plasma-free thyroxine (FT4) and thyroid-stimulating hormone (TSH) levels during the first half of pregnancy. Thyroid peripheral sensitivity was assessed by free triiodothyronine (FT3) to FT4 ratio (FT3/FT4), a proxy of deiodinase activity. GDM was diagnosed between 24 and 28 weeks of gestation by a standardized 75 g oral glucose tolerance test. Multivariable linear and logistic regression was applied to examine the associations of thyroid markers with GDM risk.

RESULTS

FT3 and FT3/FT4 were positively associated with both fasting and post-load glucose levels, while TSH, TSHI, TT4RI, and TFQI were negatively associated with 1 and 2 h post-load glucose levels. Compared with the lowest quartile, GDM risk in the highest quartile increased by 44% [odds ratio (OR) = 1.44; 95%CI, 1.08-1.92; p_trend = 0.027] for FT3 and 81% (OR = 1.81; 95%CI, 1.33-2.46; p_trend < 0.001) for FT3/FT4, while it lowered by 37% (OR = 0.63; 95%CI, 0.47-0.86; p_trend = 0.002] for TSHI, 28% for TT4RI (OR = 0.72; 95%CI, 0.54-0.97; p_trend = 0.06), and 37% for TFQI (OR = 0.63; 95%CI, 0.46-0.85; p_trend < 0.001).

CONCLUSIONS

This longitudinal study indicated that higher FT3 and FT3/FT4 and lower central thyroid resistance indices were associated with increased risk of GDM.

Perinatal effects of maternal FT3/FT4 ratio on gestational transient thyrotoxicosis

OBJECTIVE

The effects of maternal thyroid hormone levels on the course of pregnancy and birth weight have attracted interest. The aim of the present study was to consider FT3 and FT3/FT4 ratio in the evaluation of the effects of maternal thyroid functions in gestational transient thyrotoxicosis (GTT).

METHODS

This case-control study included 45 patients with GTT and 45 healthy pregnant women. Maternal history before pregnancy, thyroid function tests, thyroid autoantibodies, and thyroid ultrasonography results in 6th to 10th weeks of pregnancy were used in the differential diagnosis of GTT. In both groups, the effects of FT3, FT4 and FT3/FT4 ratios on gestational age and birth weight were evaluated.

RESULTS

There was no significant difference in the gestational age between the GTT and control groups (39,3±1,0 weeks and 39,2±1,2 weeks, respectively). Birth weights were similar in both groups (3205,2±4899 g and 3196,6±309,3 g, respectively). When maternal weight was adjusted, a positive correlation was observed between maternal FT3/FT4 ratio and birth weight (r=0,317, p=0,017). Additionally there was a positive correlation between the gestational age and the birth weight in the control group (ρ=0,726, p=0,001).

CONCLUSION

GTT had no significant effect on the gestational age and the birth weight. On the other hand an increase in the maternal FT3/FT4 ratio had a positive effect on the birth weight in the patient with GTT. Maternal characteristics (age, weight, BMI) and FT3/FT4 ratio should be taken into consideration in future impact assessment studies on this issue.

Functional and biochemical changes in the thyroid gland following exposure to therapeutic doses of external beam radiotherapy in the head-and-neck cancer patients

Context

Majority of the head-and-neck cancers are locoregionally advanced at the time of diagnosis. Hence, radiotherapy (RT) portals will invariably cover the whole neck and thus, the thyroid gland which may lead to its dysfunction.

Aims

The purpose of this study is to identify the functional and biochemical changes in the thyroid gland following RT to the neck using single-photon emission computed tomography-computed tomography (SPECT-CT) and thyroid function tests (TFTs).

Subjects and Methods

In this prospective study, 45 patients of the head-and-neck cancer, receiving RT with or without chemotherapy were investigated. Baseline TFTs and thyroid scans (on SPECT-CT) were done, and the same were repeated at the completion of RT, at 3 and 6 months.

Results

All patients received a minimum of 30 Gy to the whole neck. Baseline TFTs and thyroid scans were normal. None of them developed hypothyroidism clinical or subclinical (C/S) at the completion of RT. Six patients developed hypothyroidism (four subclinical, two clinical) at 3 months of the completion of treatment. At 6 months of follow-up 14 patients (31.1%) developed hypothyroidism (ten subclinical, four clinical) with P≤ 0.01. All patients having clinical or subclinical hypothyroidism had decreased uptake on thyroid scan. Patients having decreased uptake on thyroid scan only, with normal TFTs and no symptoms of hypothyroidism were zero at the completion of RT, 1 at 3 months follow-up, and seven at 6 months follow-up.

Conclusions

Hypothyroidism (C/S) is an under-recognized but significant complication of therapeutic doses of RT to the neck. In our study, we recognized hypothyroidism as early as 3 months following the completion of RT. Hence, tests to evaluate functional and biochemical changes in the thyroid gland should be instituted as early as 3 months following RT.

Role of non-thyroidal illness syndrome in predicting adverse outcomes in COVID-19 patients predominantly of mild-to-moderate severity

OBJECTIVE

Existing studies reported the potential prognostic role of non-thyroidal illness syndrome (NTIS), characterized by low triiodothyronine (T3) with normal/low thyroid-stimulating hormone (TSH), mainly in severe COVID-19. None considered the significant impact of SARS-CoV-2 viral load on adverse outcomes. We aimed to clarify the prognostic role of NTIS among predominantly mild-to-moderate COVID-19 patients.

DESIGN

A prospective study of COVID-19 patients.

PATIENTS AND MEASUREMENTS

Consecutive adults admitted to Queen Mary Hospital for confirmed COVID-19 from July to December 2020 were prospectively recruited. SARS-CoV-2 viral load was represented by cycle threshold (Ct) values from real-time reverse transcription-polymerase chain reaction of the respiratory specimen on admission. Serum TSH, free thyroxine and free T3 were measured on admission. The outcome was deterioration in clinical severity, defined as worsening in ≥1 category of clinical severity according to the Chinese National Health Commission guideline.

RESULTS

We recruited 367 patients. At baseline, 75.2% had mild disease, and 27 patients (7.4%) had NTIS. Fifty-three patients (14.4%) had clinical deterioration. Patients with NTIS were older, had more comorbidities, worse symptomatology, higher SARS-CoV-2 viral loads and worse profiles of inflammatory and tissue injury markers. They were more likely to have clinical deterioration (p < .001). In multivariable stepwise logistic regression analysis, NTIS independently predicted clinical deterioration (adjusted odds ratio 3.19, p = .017), in addition to Ct value <25 (p < .001), elevated C-reactive protein (p = .004), age >50 years (p = .011) and elevated creatine kinase (p = .017).

CONCLUSIONS

Non-thyroidal illness syndrome was not uncommon even in mild-to-moderate COVID-19 patients. NTIS on admission could predict clinical deterioration in COVID-19, independent of SARS-CoV-2 viral load, age and markers of inflammation and tissue injury.

Establishing paediatric reference intervals for thyroid function tests in Croatian population on the Abbott Architect i2000

Introduction

Evaluation of thyroid function is often requested and therefore defining paediatric reference intervals (RIs) is of vital importance. Currently, there is a distinct lack of paediatric RIs for thyroid function tests in Croatia. Thus, we established RIs for thyroid stimulating hormone (TSH), total triiodothyronine (TT3), total thyroxine (TT4), free triiodothyronine (FT3) and free thyroxine (FT4) in the Croatian paediatric population.

Materials and methods

Reference intervals were calculated from 397 apparently healthy children, aged from 2 days to < 19 years. Serum samples were analysed for thyroid function tests on the Abbott Architect i2000. Age- and sex-specific 95% RIs with 90% confidence intervals were established according to Clinical and Laboratory Standards Institute guidelines. To express the magnitude of sex and age variation, standard deviation ratio (SDR) was calculated using two-level nested ANOVA. The criterion for considering partitioning reference values was set to SDR > 0.3.

Results

All thyroid function tests required age partitioning, confirmed by SDR above 0.3. There was no need for sex partitioning, confirmed by SDR below 0.3. Still, FT3 was partitioned due to visually noticeable sex related difference for the oldest group (12 years to < 19 years).

Conclusion

This is the first study to establish RIs for thyroid function tests in the Croatian paediatric population. We propose RIs for widely used Abbott platform, thus giving laboratories method- and population-specific paediatric RIs for thyroid function tests that should improve clinical test interpretation.

Long COVID in Patients with Mild to Moderate Disease: Do Thyroid Function and Autoimmunity Play a Role?

Objective

Post-acute sequelae of coronavirus disease 2019 (COVID-19) or long COVID (LC) is an emerging global health issue. Fatigue is a common feature. Whether thyroid function and autoimmunity play a role is uncertain. We aimed to evaluate the prevalence and predictors of LC and the potential role of thyroid function and autoimmunity in LC.

Methods

We included consecutive adults without a known thyroid disorder who were admitted to a major COVID-19 center for confirmed COVID-19 from July to December 2020. Thyroid function tests and antithyroid antibodies were measured for all patients on admission and at follow-up. LC was defined by the presence or persistence of symptoms upon follow-up.

Results

In total, 204 patients (median age, 55.0 years; 95 men [46.6%]) were reassessed at a median of 89 days (interquartile range, 69-99) after acute COVID-19. Of the 204 patients, 41 (20.1%) had LC. Female sex (adjusted odds ratio, 2.48; P = .018) and severe acute respiratory syndrome coronavirus 2 polymerase chain reaction cycle threshold value of <25 on admission (adjusted odds ratio, 2.84; P = .012) independently predicted the occurrence of LC. Upon follow-up, most abnormal thyroid function tests in acute COVID-19 resolved, and incident thyroid dysfunction was rare. Nonetheless, we observed incident antithyroid peroxidase (anti-TPO) positivity. Although baseline or follow-up thyroid function tests were not associated with the occurrence of LC, among 172 patients with symptomatic acute COVID-19, symptom resolution was more likely in those with positive anti-TPO upon follow-up (P = .043).

Conclusion

LC is common among COVID-19 survivors, with females and those with higher viral load in acute COVID-19 particularly being vulnerable. The observation of incident anti-TPO positivity warrants further follow-up for thyroid dysfunction. Whether anti-TPO plays a protective role in LC remains to be elucidated.

The impact of metformin on hypothalamic-pituitary-thyroid axis activity in postmenopausal women with untreated non-autoimmune subclinical hypothyroidism

Metformin was found to reduce elevated thyrotropin levels in subjects with hypothyroidism. The impact on thyrotropin levels was stronger in women receiving oral contraceptive pills than in women not using any contraception. The aim of the present study was to determine whether physiological levels of oestradiol determine the effect of metformin on hypothalamic-pituitary-thyroid axis activity. The study population included 40 postmenopausal women with prediabetes and untreated non-autoimmune subclinical hypothyroidism, using (group A; n = 18) or not using (group B; n = 22) oestradiol replacement therapy. Over the entire study periods, all subjects were treated with metformin (2.55-3.00 g daily). Plasma levels of glucose, lipids, insulin, thyrotropin, free thyroxine, free triiodothyronine, prolactin, gonadotropins and oestradiol were measured, while the structure parameters of thyroid homeostasis and the degree of insulin sensitivity were calculated at the beginning of the study and 6 months later. At entry, both groups differed in gonadotropin and oestrogen levels. Despite improving insulin sensitivity, thyrotropin levels and Jostel's thyrotropin index in both study groups, these effects were stronger in group A than group B. Only in group A, metformin increased SPINA-GT, while only in group B the drug decreased FSH levels. Levels of the other variables remained at a similar level throughout the study. The effect of treatment on thyrotropin levels correlated with its baseline values, as well as with the improvement of insulin sensitivity. The results obtained suggest that the impact of metformin on hypothalamic-pituitary-thyroid axis activity depends on the oestrogen status of patients.

Influence of educational level on test and treatment for incident hypothyroidism

OBJECTIVE

The incidence of hypothyroidism is not expected to differ by socioeconomic factors. However, the decision to test and initiate treatment may differ. We aimed to examine whether educational level influences the probability of thyroid stimulation hormone (TSH)-measurement and initiation of levothyroxine treatment.

DESIGN

Citizens in the greater Copenhagen Area during 2001-2015 were included. Individual-level data on educational level, diagnoses, GP-contact, TSH-measurement and medication were derived from administrative and healthcare registers. The relative risks (RR) between educational levels of annual TSH-measurement and treatment initiation following a TSH-measurement were analysed in Poisson regression models with generalized estimation equations.

RESULTS

A TSH-measurement was performed in 19% of 9,390,052 person years. The probability of TSH-measurement was higher with short (RR 1.16 [95% CI 1.15-1.16]) and medium (RR 1.11 [95% CI 1.06-1.12]) compared with long education. Treatment was initiated after 0.8% of 2,049,888 TSH-measurements. For TSH < 5 mIU/L, RR for treatment initiation ranged between 0.47 (95%CI 0.39-0.57) and 0.78 (95%CI 0.67-0.91) for short and medium compared with long education. For TSH 5-10 mIU/L, there was no statistically significant difference. For TSH > 10 mIU/L, RR was 1.07 (95% CI 1.02-1.12) for short and 1.08 (95% CI 1.03-1.13) for medium compared with long education.

CONCLUSION

The probability of TSH-measurement was higher with shorter education, and the probability of treatment initiation with TSH > 10 mIU/L was marginally higher with short-medium education compared with long education. However, the probability of treatment initiation with TSH < 5 mIU/L, that is treatment incongruous with guidelines, was substantially higher in persons with long education.

Thyroid Laboratory Testing and Management in Women on Thyroid Replacement Before Pregnancy and Associated Pregnancy Outcomes

Background: Women with hypothyroidism before pregnancy often require an increase in their levothyroxine dosage to maintain a euthyroid state during pregnancy. The objectives of this study were to investigate: (i) the frequency and distribution of thyrotropin (TSH) testing and levothyroxine dosage adjustment by gestational age, (ii) the magnitude of levothyroxine increase by the underlying etiology of hypothyroidism, and (iii) the relationship of overtreatment or undertreatment during pregnancy with adverse pregnancy outcomes among women using thyroid replacement before pregnancy. Methods: A retrospective cohort study of pregnancies in women on thyroid replacement before pregnancy in Alberta, Canada, was performed. Women using thyroid replacement anytime during the two years before pregnancy who delivered between October 2014 and September 2017 were included. Delivery records, physician billing, and laboratory and pharmacy administrative data were linked. Outcomes included characteristics of TSH testing, levothyroxine dosing, and pregnancy outcomes. The frequency and gestational timing of TSH testing and levothyroxine adjustments were calculated. Multiple logistic regression was used to test whether pregnancies with TSH <0.10 mIU/L (overtreatment) or TSH ≥10.00 mIU/L (undertreatment) compared with control pregnancies (TSH 0.10-4.00 mIU/L) were associated with adverse pregnancy and neonatal outcomes. Results: Of the 10,680 deliveries, 8774 (82.2%) underwent TSH testing at least once during pregnancy, at a median gestational age of six weeks. An adjustment of levothyroxine dosage was made for 4321 (43.7%) during pregnancy. TSH in pregnancy below 0.10 mIU/L increased the odds of preterm delivery when compared with control pregnancies (adjusted odds ratio, 2.14 [95% confidence interval 1.51-2.78]). TSH ≥10.00 mIU/L during pregnancy was not associated with any adverse pregnancy or neonatal outcomes in the multivariable analysis. Conclusions: Although most women on thyroid replacement before conception had TSH measured at some point during pregnancy, it is concerning that 17.8% did not. Levothyroxine overtreatment in pregnancy was associated with preterm delivery. These findings suggest that clinicians should be careful to avoid overtreatment with levothyroxine in pregnancy.

Association between oral health and thyroid disorders: A population-based cross-sectional study

OBJECTIVES

In this study, we aimed to determine the relationship between oral health status and thyroid dysfunction.

METHODS

A population-based cross-sectional analysis using data from the Korean National Health and Nutrition Examination Survey (KNHNES) was performed. We investigated the association between oral health-related parameters and the prevalence of thyroid diseases. In addition, the relationship between oral health status and thyroid function test (TFT) results was analyzed. One-way analysis of variances or chi-square test was used for comparisons between oral health-related parameters and presence of thyroid diseases. Univariable and multivariable logistic regression analyses were conducted to evaluate the associations between participants' characteristics including oral health-related parameters and the abnormal results of TFTs.

RESULTS

A total of 18,034 adults were surveyed. Histories of thyroid diseases were found to be more common in people who brushed their teeth frequently or used oral hygiene products. However, histories of periodontitis and community periodontal index (CPI) did not show significant associations with histories of thyroid diseases. Among 14,860 participants without history of thyroid disorders, people having higher CPI values demonstrated higher probabilities of abnormal TFTs (OR 1.381, 95% CI 1.241-1.537, p < .0001); however, statistical significance was not found after adjusting for the other variables.

CONCLUSIONS

Our study demonstrated that good oral health-related behavior was associated with more frequent thyroid disease history. High CPI showed a significant association with TFT abnormalities; however, the significance of this association became lower when other variables such as age and sex were adjusted. Further studies will be needed to determine how the control of oral health-related conditions actually has a causal relationship with thyroid disease/dysfunction through prospective cohort studies.

Microwave ablation of symptomatic benign thyroid nodules: Short- and long-term effects on thyroid function tests, thyroglobulin and thyroid autoantibodies

OBJECTIVE

Microwave ablation therapy has been attracting great attention due to its advantages such as low complication rate, good cosmetic results and effective nodule shrinking. Although the effect of thermal ablation therapy on the nodule volume reduction rate has been shown several studies, a limited number of papers have been reported for the effects of microwave ablation (MWA) on thyroid function tests. The aim of this study was to investigate the short- and long-term effects of MWA therapy on thyroid function tests (TFTs), thyroglobulin (Tg) and thyroid autoantibodies in euthyroid patients.

DESIGN, PATIENTS AND MEASUREMENTS

Demographic data of the patients, TFTs, Tg, thyroid autoantibodies and thyroid volume of the nodules were recorded before the procedure and follow-up. Any differences in serum thyroid hormone levels were investigated in pre-, post- and 6-month follow-up periods before and after MWA.

RESULTS

The difference between all thyroid hormone levels at pre MWA and 24 h after MWA was statistically significant (p < .001). FT3 (4.62) pmol/L and FT4 (10.81) pmol/L median levels increased significantly (p < .001), while thyrotropin (TSH) levels decreased at 24 h after MWA (p < .001). Thyroid antibodies levels were not statistically different at 6-month (p > .05), whereas Tg levels decreased (p < .001) compared to pre MWA.

CONCLUSIONS

While no significant effect was observed at 6 month, the effect of MWA on thyroid function tests was prominent at 24 h.

Cushing's Syndrome Effects on the Thyroid

The most known effects of endogenous Cushing’s syndrome are the phenotypic changes and metabolic consequences. However, hypercortisolism can exert important effects on other endocrine axes. The hypothalamus–pituitary–thyroid axis activity can be impaired by the inappropriate cortisol secretion, which determinates the clinical and biochemical features of the “central hypothyroidism”. These findings have been confirmed by several clinical studies, which also showed that the cure of hypercortisolism can determine the recovery of normal hypothalamus–pituitary–thyroid axis activity. During active Cushing’s syndrome, the “immunological tolerance” guaranteed by the hypercortisolism can mask, in predisposed patients, the development of autoimmune thyroid diseases, which increases in prevalence after the resolution of hypercortisolism. However, the immunological mechanism is not the only factor that contributes to this phenomenon, which probably includes also deiodinase-impaired activity. Cushing’s syndrome can also have an indirect impact on thyroid function, considering that some drugs used for the medical control of hypercortisolism are associated with alterations in the thyroid function test. These considerations suggest the utility to check the thyroid function in Cushing’s syndrome patients, both during the active disease and after its remission.

Inflammation-Related Markers and Thyroid Function Measures in Pediatric Patients: Is the Grade of Obesity Relevant?

We aimed to investigate the effect of weight status on inflammation-related markers and thyroid function tests in overweight and obese pediatric patients. Children and adolescents diagnosed between January 2017 and January 2019 with overweight or obesity were included in the study. Neutrophil-to-lymphocyte ratio (NLR), platelet-to lymphocyte ratio (PLR) and systemic immune-inflammation index (SII) were calculated for the groups defined according to Body Mass Index (BMI)-for-age z-score: overweight (≥1 BMI-for-age z-score), obese (≥2 BMI-for-age z-score) and severely obese (≥3 BMI-for-age z-score). Severely obese patients had significantly higher value of white blood cells (WBC) counts (median = 7.92) compared with overweight patients (7.37, p = 0.014). Absolute lymphocyte count was significantly associated with obesity degree in children (Spearman’s Rho coefficient ρ = 0.228. p = 0.035), whereas absolute polymorphonuclear neutrophils (PMNCs) count was significantly higher in severely obese adolescents than overweight adolescents (overweight: 4.04 vs. severely obese: 5.3 (p = 0.029)). In 8.19% of patients an elevated thyroid-stimulating hormone (TSH) level was found, and 3.36% of patients had a low level of free thyroxine with an elevated level of TSH. Total absolute WBC count may be a reliable inflammation-related marker in obese pediatric patients without metabolic syndrome, but needs to be validated in the context of all possible covariates. Subclinical and overt hypothyroidism may develop from an early age in overweight or obese patients.

Thyroid Dysfunction in Relation to Immune Profile, Disease Status, and Outcome in 191 Patients with COVID-19

OBJECTIVE

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-related thyroiditis is increasingly recognized. The role of thyroid autoimmunity and SARS-CoV-2 viral load in SARS-CoV-2-related thyroid dysfunction is unclear. We evaluated the thyroid function of a cohort of coronavirus disease 2019 (COVID-19) patients, in relation to their clinical features, and biochemical, immunological, and inflammatory markers.

METHODS

Consecutive adult patients, without known thyroid disorders, admitted to Queen Mary Hospital for COVID-19 from July 21 to August 21, 2020, were included. Serum levels of thyroid-stimulating hormone (TSH), free thyroxine, free triiodothyronine (fT3), and antithyroid antibodies were measured on admission.

RESULTS

Among 191 patients with COVID-19 (mean age 53.5 ± 17.2 years; 51.8% male), 84.3% were mild, 12.6% were moderate, and 3.1% were severe. Abnormal thyroid function was seen in 13.1%. Ten patients had isolated low TSH, suggestive of subclinical thyrotoxicosis due to thyroiditis, although the contribution of autoimmunity was likely in 2 of them. Autoimmune thyroiditis probably also contributed to subclinical hypothyroidism in another patient. Ten patients had isolated low fT3, likely representing nonthyroidal illness syndrome. Lower SARS-Cov-2 polymerase chain reaction cycle threshold values and elevated C-reactive protein were independently associated with occurrence of low TSH (P = .030) and low fT3 (P = .007), respectively. A decreasing trend of fT3 with increasing COVID-19 severity (P = .032) was found. Patients with low fT3 had more adverse COVID-19-related outcomes.

CONCLUSION

Around 15% of patients with mild to moderate COVID-19 had thyroid dysfunction. There may be a direct effect of SARS-CoV-2 on thyroid function, potentially leading to exacerbation of pre-existing autoimmune thyroid disease. Low fT3, associated with systemic inflammation, may have a prognostic significance.

Etiological Association Between Psoriasis and Thyroid Diseases

Psoriasis is a chronic relapsing/remitting autoimmune disease affecting skin and fingernails. It is associated with many other autoimmune diseases such as rheumatoid arthritis, celiac disease, Crohn's disease, and thyroid diseases. Two important autoimmune thyroid diseases - Hashimoto's thyroiditis (hypothyroidism) and Grave's disease (hyperthyroidism) - affect the body's significant organs such as the brain, muscles, digestive function, and the skin. Although some studies have established the connection between psoriasis and thyroid diseases with autoimmunity, our article provides an in-depth analysis of the connection between these two diseases and other common etiological factors associated with them, along with autoimmunity.

We reviewed articles from PubMed using regular keywords and Medical Subject Headings (MeSH) keywords and finalized 45 articles to find an association between these two diseases. These articles showed that this association is more prevalent in obese patients and late-onset psoriasis. Most of the articles showed a positive association, but few articles showed no connection between them. However, there is no concrete explanation to prove the association due to limited research; additional studies are necessary. It requires the attention of both clinicians and researchers to develop a universal drug that will work on both diseases, and also thyroid evaluation could be included in psoriatic patient care so that there is a possibility to decrease cost and efforts while treating these diseases. 

The Impact of Interferon Beta-1b Therapy on Thyroid Function and Autoimmunity Among COVID-19 Survivors

BACKGROUND

Some studies have indicated that interferon (IFN) may be valuable in COVID-19. We aimed to evaluate the impact of short-term IFN on incident thyroid dysfunction and autoimmunity among COVID-19 survivors.

METHODS

We included consecutive adults without known thyroid disorder admitted to Queen Mary Hospital for COVID-19 from July 2020 to January 2021 who had thyroid function tests (TFTs) and anti-thyroid antibodies measured both on admission and at three months.

RESULTS

226 patients were included (median age 55.0 years; 49.6% men): 135 were IFN-treated. There tended to be more abnormal TFTs upon reassessment in IFN-treated patients (8.1% vs 2.2%, p=0.080). 179 patients (65.4% IFN-treated) had a complete reassessment of anti-thyroid antibodies. There were significant increases in titres of both anti-thyroid peroxidase antibodies (anti-TPO: baseline 29.21 units [IQR: 14.97 - 67.14] vs reassessment 34.30 units [IQR: 18.82 - 94.65], p<0.001) and anti-thyroglobulin antibodies (anti-Tg: baseline 8.23 units [IQR: 5.40 - 18.44] vs reassessment 9.14 units [IQR: 6.83 - 17.17], p=0.001) in the IFN-treated group but not IFN-naïve group. IFN treatment (standardised beta 0.245, p=0.001) was independently associated with changes in anti-TPO titre. Of the 143 patients negative for anti-TPO at baseline, 8 became anti-TPO positive upon reassessment (seven IFN-treated; one IFN-naïve). Incident anti-TPO positivity was more likely to be associated with abnormal TFTs upon reassessment (phi 0.188, p=0.025).

CONCLUSION

IFN for COVID-19 was associated with modest increases in anti-thyroid antibody titres, and a trend of more incident anti-TPO positivity and abnormal TFTs during convalescence. Our findings suggest that clinicians monitor the thyroid function and anti-thyroid antibodies among IFN-treated COVID-19 survivors, and call for further follow-up studies regarding the clinical significance of these changes.

Characterization of Fetal Thyroid Levels at Delivery among Appalachian Infants

Thyroid disorders are a frequently encountered issue during pregnancy and a cause of maternal and fetal morbidity. In regions like Appalachia that are particularly susceptible to health disparities, descriptive studies are needed to assist in identifying pathologic derangements. We sought to characterize fetal thyroid hormone levels at delivery and investigate whether or not maternal demographic characteristics affect the prevalence of neonatal thyroid disease. A cross-sectional analysis was conducted on 130 pregnant women recruited from the Tri-State region, incorporating areas of Kentucky, Ohio, and West Virginia. Total triiodothyronine (T3) (p = 0.4799), free T3 (p = 0.6323), T3 uptake (p = 0.0926), total thyroxine (T4) (p = 0.8316), free T4 (p = 0.0566), and Thyroid stimulating hormone (TSH) (p = 0.8745) levels were comparable between urban and rural newborns. We found no effect of hypertension status or nicotine levels on fetal umbilical cord thyroid hormone levels. Maternal diabetic status was associated with lower T4 (p = 0.0099) and free T4 (p = 0.0025) levels. Cotinine affected levels of T4 (p = 0.0339). In regard to maternal Body Mass Index (BMI), there was an increase in total T3 as BMI increased (p = 0.0367) and no significant difference in free T3, T3 uptake, T4, free T4, or TSH. There was a negative correlation between TSH and 1 min Apgar scores (p = 0.0058). Lead and cadmium have been implicated to alter TSH levels, but no correlation was found in our study (r² = 0.0277). There were no differences in cord blood between urban (37.3 ± 10.3 fmol/ug DNA) and rural (70.5 ± 26.8 fmol/ug DNA) benzo(a)pyrene DNA adducts (p = 0.174). Thyroid disorders present a unique opportunity for the prevention of perinatal morbidity and mortality, since maternal treatment, as well as maternal demographic characteristics, can have direct fetal effects.

Pituitary hyperplasia mimicking thyrotropin-producing pituitary adenoma in the patient with resistance to thyroid hormone: a case report

The syndrome of inappropriate thyroid-stimulating hormone (TSH) secretion is characterized by high circulating thyroid hormone concentrations in the presence of non-suppressed TSH. After exclusion of the laboratory interference, TSH-secreting pituitary adenoma (TSHoma) or resistance to thyroid hormone-beta (RTH-β) should be suspected. The presence of a pituitary adenoma on the hypothalamic-pituitary imaging supports the diagnosis of TSHoma. However, the incidental findings of non-functioning pituitary adenomas may appear in patients with RTH-β. Abnormal MRI finding in the RTH-β patient also includes pituitary enlargement from thyrotroph hyperplasia. We herein reported a patient with inappropriate TSH secretion who has pituitary hyperplasia mimicking TSHoma. This case illustrates the diagnostic tests to distinguish an RTH-β from TSHoma.

Interpretation of thyroid function tests during pregnancy

Thyroid hormones are crucial for normal pregnancy and fetal development. Large physiological changes occur during pregnancy, posing challenges for the correct interpretation of thyroid function tests. TSH concentrations are the principal first test to rule out thyroid disease taking into account trimester-specific reference ranges. Free T4 (FT4) measurements by immuno-assays may be subject to interference by endogenous and exogenous factors. The relevance of measuring free T3 (FT3) during pregnancy is unclear. Thyroid autoimmunity is well-reflected by the presence of antibodies against TPO. TPO-antibody positivity is associated with an increased risk of adverse pregnancy outcomes.

Trimester-specific reference intervals of thyroid function tests in Turkish pregnants

Physiological changes in hormone levels occur in thyroid gland during pregnancy. Screening of the thyroid hormone levels and determining trimester-specific reference intervals in pregnancy are important. Guidelines recommend the use of trimester-specific reference ranges for each country. The aim of this study is to determine trimester-specific thyroid function reference intervals for pregnancy in Turkish population. In total, 5000 patients were screened out of which 1258 patients have all of fT3, fT4 and TSH levels measured, were included in the study. Patients were grouped as follows: 482 women were in first trimester, 361 women were in second trimester, and 415 women were in third trimester. All analyses were performed by means of chemiluminescence methods (Liaison^®; DiaSorin S.p.A., Saluggia, Italy). The TSH reference intervals were 0.005-3.65, 0.01-3.63, and 0.2-3.46 mIU/L at the first, the second, and the third trimesters of pregnancy, respectively. The fT4 reference intervals were 0.72-1.79, 0.71-1.26, and 0.65-1.12 ng/dL at the first, the second, and the third trimesters, respectively. The fT3 reference intervals were 2.45-4.03, 2.37-3.85, and 2.31-3.77 ng/dL at the first, the second, and the third trimesters, respectively. It is crucial to determine population- and gestational-specific reference intervals for trustworthy treatment of pregnants.

Trimester-Specific Reference Intervals for Thyroid Function Parameters in Indian Pregnant Women during Final Phase of Transition to Iodine Sufficiency

BACKGROUND

Interpretation of thyroid function tests during pregnancy depends on gestational age, method, and population-specific reference intervals. Therefore, there is a worldwide trend to establish trimester-specific levels for different populations. The aim of this study was to establish a trimester-specific reference range for thyroid function parameters during pregnancy in Indian women.

MATERIALS AND METHODS

Thyroid function tests (TSH, FT4, TT4, TT3) of 80, 76, and 73 women at 1^st, 2^nd, and 3^rd trimester, respectively, and 168 nonpregnant women were analyzed after exclusion of low UIC(<150 μg/L) and anti-TPO positivity(>35 IU/ml). Urinary iodine excretion (UIC) was assessed in all. The 2.5^th and 97.5^th percentile values were used to determine the reference ranges for thyrotropin (TSH), free thyroxine (FT4), total thyroxine (TT4), and total triiodothyronine (TT3) for each trimester of pregnancy.

RESULTS

The reference range for TSH for first trimester was 0.19-4.34 μIU/ml, for second trimester 0.46-4.57 μIU/ml, and for third trimester 0.61-4.62 μIU/ml. The reference range during three trimesters for FT4 (ng/dl) was 0.88-1.32, 0.89-1.60, and 0.87-1.54, for total T4 (μg/dl) was 5.9-12.9, 7.4-15.2, and 7.9-14.9. In nonpregnant women, FT4 was 0.83-1.34, total T4 was 5.3-11.8, and TSH was 0.79-4.29. The mean UIC in nonpregnant women was 176 ± 15.7 μg/L suggesting iodine-sufficiency in the cohort.

CONCLUSION

The trimester-specific TSH range in pregnant women in this study is not significantly different from nonpregnant reference range in the final phase of transition to iodine sufficiency in India.

Screening for thyroid disease in patients with type 2 diabetes mellitus: An evaluation of current practice

BACKGROUND

United Kingdom national guidelines do not recommend routine testing for thyroid disease in people with type 2 diabetes mellitus (T2DM). However, some studies suggest an increased risk of thyroid dysfunction in T2DM. The aim of this study was to evaluate the current practice of screening for thyroid disease in patients with T2DM.

METHODS

Patients with pre-existing T2DM (n = 339) were selected from records for routine glycated haemoglobin testing performed in December 2008. Using routinely collected primary/secondary care data from 2009 to 2017, we examined longitudinal thyroid-stimulating hormone and free thyroxine requests to determine the overall proportion of patients screened for thyroid dysfunction and the time interval between thyroid tests requested.

RESULTS

Thirty-three patients (9.7%) had pre-existing thyroid disease. Of the remaining 306 patients, 96.4% had at least one thyroid test during the follow-up period. When the time interval between tests was evaluated in these patients, there was a discrete peak in thyroid function test requests at 12 months, consistent with routine annual testing. Most requests (77%) originated from a general practice setting.

CONCLUSIONS

Contrary to current guidelines, we have provided evidence suggestive of regular screening for thyroid dysfunction in patients with T2DM, particularly in general practice. The appropriateness of this practice remains unclear, but may warrant further examination to assess the clinical benefits of screening, balanced against cost.

Assessment of biotin interference in thyroid function tests

The aim of the study was to systematically characterize the interference of biotin on thyroid function tests and biotin washout periods.Ten healthy adults were recruited with administration of 5 and 10 mg/d biotin for 7 days. Analyte concentrations of thyroid function tests were measured at baseline prior to starting biotin and from 2 hours to 2 days after withdrawal of 5 and 10 mg/d biotin. The outcomes were compared the baseline with the several points after taking biotin at Roche cobas e602, Beckman UniCel DxI 800, and Abbott Architect 2000 immunoassay platforms, respectively.Ingesting 5 or 10 mg/d of biotin for 7 days could produce positive or negative interference among the thyroid function tests at Roche cobas e602 and Beckman UniCel DxI 800 systems, but no interference on Abbott Architect 2000. Interference duration of 5 mg/d biotin for Roche cobas e602 and Beckman UniCel DxI 800 of thyroid function tests lasted for 8 hours, while 10 mg/d biotin interfered with Roche cobas e602 or Beckman UniCel DxI 800 for 1 day or 2 days.This study provides valuable guidance on biotin washout periods at doses common in over-the-counter supplements necessary to avoid false assay results.Trial registration: ChiCTR1800020472.