Incidence and risk factors of transient hypothyroxinemia of prematurity: a prospective cohort study

BACKGROUND

Transient hypothyroxinemia of prematurity (THOP) is characterized by low thyroxine (T4) levels with normal thyroid-stimulating hormone (TSH) levels. This study aimed to determine the incidence and factors associated with THOP.

METHODS

This prospective cohort study included neonates who were born before 37 weeks of gestation in the neonatal intensive care unit (NICU) between April 2017 and December 2020. Serum TSH and free thyroxine (FT4) levels were routinely screened at 3-5 days and 2, 4, and 6-8 weeks postnatally. The criteria for diagnosis of THOP were a TSH level < 7 mU/L with a FT4 level < 0.8 ng/dL at any screening timepoint.

RESULTS

The incidence of THOP in infants born before 28, 34, and 37 weeks of gestation was 39.5 (17/43), 8.4% (29/343), and 4.8% (35/722), respectively. A multivariate analysis revealed that a gestational age of < 28 weeks (adjusted odds ratio [aOR]: 5.35, 95% confidence interval [CI]: 1.89-15.13, p=0.002); 5-min Apgar score of ≤3 (aOR: 5.72, 95% CI: 2.2-14.89, p < 0.001); and treatment with aminophylline (aOR: 2.95, 95% CI: 1.08-8.11, p=0.037), dobutamine (aOR: 4.12, 95% CI: 1.55-10.98, p=0.004), or morphine (aOR: 4.91, 95% CI: 1.29-18.74, p=0.011) were associated with an increased risk of THOP. The TSH and FT4 levels in infants with THOP returned to normal ranges by 2 weeks of age.

CONCLUSIONS

THOP is frequently found in preterm infants. An extremely low gestational age, a low Apgar score, and the use of certain medications in the NICU are risk factors for the development of THOP. Therefore, a thyroid screening program should be implemented for evaluating congenital hypothyroidism (CH) and THOP in preterm neonates in all settings.

The effect of subclinical hypothyroidism on ovarian volume in prepubertal girls

OBJECTIVE

Enlargement and cystic changes in ovaries of patients with long-standing overt hypothyroidism have been described in numerous case reports. However, there are limited data about the effect of subclinical hypothyroidism (SH) on ovarian volume. The aim of the study is to evaluate the relationship between serum thyroid stimulating hormone (TSH) level and ovarian volume in prepubertal girls with SH.

METHODS

Patients who were aged between 6 and 10 years and diagnosed with SH and age-matched healthy euthyroid controls were enrolled in the study. All subjects were prepubertal.

RESULTS

Thirty-five children with SH (mean age; 7.6±1.0 years) and 50 euthyroid healthy girls (mean age; 7.7±1.2 years) were enrolled in the study. TSH and LH levels and both ovarian volumes were significantly higher in SH group than controls (p<0.05). In addition, TSH was positively correlated with ovarian volumes and LH in patients with SH (p<0.05).

CONCLUSION

The results of this study showed that ovarian volumes of prepubertal girls with SH were significantly greater than those with normal thyroid function. Although ovarian enlargement and cyst formation is well recognized in long-standing overt hypothyroidism, it has been shown for the 1^st time in patients with SH.

Hypothyroidism After Use of Immune Checkpoint Inhibitor Therapy in Patient With Graves' Disease: Cure?

Immune checkpoint inhibitors (ICIs) are frequently used as treatment for many malignancies. Immune-related adverse events (irAEs) due to use of ICIs are common. Thyroid involvement is the most common endocrine irAE. Here, we present an unusual case of Graves' disease potentially cured due to destructive thyroiditis caused by inflammation due to ICIs. Thyroid irAEs are more common with programmed cell death protein-1 (PD-1) inhibitor or programmed cell death-ligand 1 (PD-L1) inhibitors than cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) inhibitors. Baseline and serial monitoring of thyroid function tests is recommended.

Spontaneous Ovarian Hyperstimulation Syndrome Associated With Primary Hypothyroidism

Ovarian hyperstimulation syndrome is a rare condition in pregnant women. Most cases are associated with the use of ovulation induction and stimulation medications. Some studies have reported cases of this condition in non-pregnant women or women undergoing ovulation therapy. In this case report, we report the case of a 27-year-old pregnant Saudi woman presenting with a picture of severe spontaneous ovarian hyperstimulation syndrome secondary to severe undiagnosed hypothyroidism. Treatment with Eltroxin (thyroxine) led to complete improvement and regression of ovarian enlargement after empirical titrating thyroxin replacement therapy, which proved the presence of this causation. The diagnosis was confirmed by laboratory and imaging findings, which helped prompt management and prevented complications of unneeded surgical intervention.

Iodine nutrition level and thyroid function in pregnant women in the Yongchuan district of Chongqing

BACKGROUND AND AIM

This study aims to investigate thyroid function-associated parameters and the incidence of thyroid disorders in pregnant women, with the overarching aim to ensure that pregnant women do not develop said disorders due to aberrant iodine levels during the course of pregnancy.

METHODS

A total of 300 pregnant women who underwent routine check-ups at the Yongchuan Hospital Affiliated to Chongqing Medical University from January to December 2021 were enrolled. Venous blood and morning urine were collected. Serum thyroid-stimulating hormone (TSH), free thyroxine (FT4), and free triiodothyronine (FT3) were determined by chemiluminescence immunoassay. Urinary iodine concentration (UIC) was detected by arsenic cerium catalytic spectrophotometry. Thyroid disorders were extrapolated from the measured parameters.

RESULTS

The overall median UIC was 203 μg/L, which was within normal range. Subgroup analysis revealed that the median UIC in the first trimester was 187.5 μg/L, 211.8 μg/L in the second trimester, and 239.9 μg/L in the third trimester. However, based on the WHO criteria, 32%, 30%, and 18% of pregnant women were iodine deficient during their first, second, and third trimester, respectively. The proportion of women with iodine deficiency in the first and second trimesters was higher compared to the third trimester (P < 0.05). Serum FT3 and FT4 concentrations were higher in subjects in their first and second trimester versus the third trimester, while serum TSH levels were lower in subjects in their first and second trimester versus the third trimester (P < 0.05). The TSH concentration in subjects with inadequate iodine intake (UIC < 150 μg/L) was lower compared to subjects with adequate iodine intake (UIC 150 - 249 μg/L), but higher than in subjects with more than adequate intake (UIC 250 - 499 μg/L) and excess iodine intake (UIC ≥ 500 μg/L) (P < 0.05). TSH concentration and UIC were positively correlated (r = 0.1945, P = 0.0007), while no relationship was observed between UIC and FT3 and FT4 serum levels (r₁ = -0.0593, P₁ = 0.3053; r₂ = -0.0149, P₂ = 0.7968). There was no significant difference in FT3 and FT4 concentration between different UIC strata (P > 0.05). The incidence of thyroid disease during pregnancy in iodine-deficient women was greater compared to pregnant women with adequate iodine intake (P < 0.05) and higher in subjects in the more than adequate as well as excessive iodine intake cohorts (P < 0.05).

CONCLUSION

The iodine nutritional intake by pregnant women in Yongchuan District, Chongqing, was generally sufficient to meet developmental and metabolic needs. However, about a third of women in their first and second trimester exhibited iodine deficiency. Iodine deficiency was associated with an increased incidence of thyroid diseases.

RELEVANCE FOR PATIENTS

In clinical practice, the UIC of pregnant women should be measured during key stages in the pregnancy to prevent the manifestation of thyroid diseases.

The associations between thyroid-related hormones and the risk of thyroid cancer: An overall and dose-response meta-analysis

Objective

Thyroid cancer (TC) is one of the most common malignant tumours of the endocrine system. Thyroid-stimulating hormone (TSH) is known as being a risk factor for TC, but other thyroid-related hormones are inconsistently associated with TC. The purpose of this study was to comprehensively evaluate the relationships between thyroid-related hormones and the risk of TC.

Methods

This study utilized searches of PubMed, Embase, Web of Science and Cochrane library up to the date of March 31st, 2022. Additionally, we performed a systematic review of related original studies combining overall and dose-response meta-analyses.

Results

A total of 30, 5 and 7 articles were included in the meta-analyses of TSH, Free triiodothyronine (FT3), free thyroxine (FT4) and TC risk with 58437, 6813 and 7118 participants respectively. An increased risk of TC was associated with high TSH exposure (OR=1.28, 95% CI: 1.19-1.37, P < 0.001) in the overall meta-analysis. For every 1 mU/L increase in TSH, the risk of TC increased by 16%. However, in those studies that used healthy subjects as controls, the association was not statistically significant(P=0.62). Additionally, high serum FT3 demonstrated a reduced risk of TC, with a combined OR of 0.86 in the fixed-effect model (95% CI: 0.81-0.90, P < 0.001). In addition, a statistically significant increase in TC risk was found when FT4 concentrations reached a certain threshold (approximately 2.2 ng/dL) in the dose-response meta-analysis.

Conclusions

Significant associations between thyroid-related hormones and the risk of TC were found in this study. Further research is needed to understand the underlying mechanisms.

Subclinical hyperthyroidism in children

Subclinical hyperthyroidism (SH) is defined as serum thyroid-stimulating hormone (TSH) below the lower limit of the reference range in the presence of normal free T4 and free T3 levels. Depending on the degree of TSH suppression, SH could be defined as mild (TSH, 0.1-0.45 mU/L) or severe (TSH<0.1 mU/L). Patients with SH are often asymptomatic when symptoms are present, they are similar to the symptoms in patients with overt hyperthyroidism, although they are usually milder. The management of the SH is uncertain and should be individualized. We present this review after an extensive literature search and long-standing clinical experience. This review provides the prevalence, causes, clinical presentation, investigation, and therapeutic approach of SH in children.

Thyrotropin Levels in Patients with Coronavirus Disease 2019: Assessment during Hospitalization and in the Medium Term after Discharge

BACKGROUND

The objectives of this study were (1) to compare TSH levels between inpatients with critical versus non-critical coronavirus disease 19 (COVID-19), and (2) to describe the status of TSH levels three months after hospitalization.

METHODS

We collected data on adult patients hospitalized with COVID-19 at Amiens University Hospital. We compared TSH levels between inpatients with critical (intensive care unit admission and/or death) versus non-critical COVID-19. Thereafter, survivors were invited to return for a three-month post-discharge visit where thyroid function tests were performed, regardless of the availability of TSH measurement during hospitalization.

RESULTS

Among 448 inpatients with COVID-19, TSH assay data during hospitalization were available for 139 patients without prior thyroid disease. Patients with critical and non-critical forms of COVID-19 did not differ significantly with regard to the median (interquartile range) TSH level (0.96 (0.68-1.71) vs. 1.27 mIU/L (0.75-1.79), p = 0.40). Abnormal TSH level was encountered in 17 patients (12.2%); most of them had subclinical thyroid disease. TSH assay data at the three-month post-discharge visit were available for 151 patients without prior thyroid disease. Only seven of them (4.6%) had abnormal TSH levels. Median TSH level at the post-discharge visit was significantly higher than median TSH level during hospitalization.

CONCLUSIONS

Our findings suggest that COVID-19 is associated with a transient suppression of TSH in a minority of patients regardless of the clinical form. The higher TSH levels three months after COVID-19 might suggest recovery from non-thyroidal illness syndrome.

Levothyroxine malabsorption or pseudomalabsorption? A question in the management of refractory hypothyroidism

PURPOSE

The levothyroxine absorption test (LT4AT) is an important tool for distinguishing hypothyroidism due to malabsorption from 'pseudomalabsorption' conditions. Our aim was to review our institution's LT4AT results and assess its role in the management of patients with refractory hypothyroidism.

METHODS

We performed a retrospective study of all patients evaluated for refractory hypothyroidism who underwent LT4AT in our tertiary center between 2014 and 2020. Its results and the impact on thyroid function management during follow-up were assessed.

RESULTS

Ten female patients were included with a mean age of 40 years (min-max: 26-62). Mean weight was 72 kg (min-max: 43-88) and baseline LT4 dosage ranged from 2.5 to 5.3 µg/kg/day. The most common causes of hypothyroidism were postsurgical in 50% (n = 5) and autoimmune in 20% (n = 2). During LT4AT, normal LT4 absorption was found in all but one individual (mean FT4 increase of 231%, min-max: 85-668). The only patient with objective LT4 absorption impairment (maximal increase of 48% by hour 5) presented also Helicobacter pylori gastritis and prior history of 'intestinal surgery' during childhood. No adverse events were reported during any of the LT4ATs. During follow-up (median 11.5 months (IQR 23)), three patients obtained euthyroidism and six had improved their hypothyroidism state.

CONCLUSIONS

The LT4AT is an effective and safe way to assess refractory hypothyroidism and provides valuable information to distinguish LT4 malabsorption from 'pseudomalabsorption'. Our data suggest that most patients with suspicious LT4 malabsorption perform normally during LT4AT. This test provides relevant information for better management of patients with refractory hypothyroidism.

The Hypothalamic-Pituitary-Thyroid Axis Equivalent in Normal and Cancerous Oral Tissues: A Scoping Review

The hypothalamic-pituitary-thyroid (HPT) axis is crucial in regulating thyroid hormone levels that contribute to the development and homeostasis of the human body. Current literature supports the presence of a local HPT axis equivalent within keratinocytes of the skin, with thyroid hormones playing a potential role in cancer progression. However, this remains to be seen within oral tissue cells. An electronic search of Scopus and PubMed/Medline databases was conducted to identify all original publications that reported data on the production or effects of HPT axis components in normal or malignant cells of the oral cavity. The search identified 221 studies, of which 14 were eligible. Eight studies were retrospective analyses of clinical samples, one study involved both in vivo and in vitro experiments, and the remaining five studies were conducted in vitro using cell lines. The search identified evidence of effects of HPT components on oral cancer cells. However, there were limited data for the production of HPT axis components by oral tissues. We conclude that a possible role of the local HPT axis equivalent in the oral mucosa may not be established at present. The gaps in knowledge identified in this scoping review, particularly regarding the production of HPT components by oral tissues, warrant further investigation.

Thyroid-Stimulating Hormone as a Biomarker for Stress After Thyroid Surgery: A Prospective Cohort Study

BACKGROUND Thyroid-stimulating hormone (TSH), which is regulated by the negative feedback of triiodothyronine (T3) and thyroxine (T4), is affected by cortisol (a stress hormone) and cytokines during allostasis. Thus, we assessed changes in TSH levels under stress and its potential as a stress marker in patients lacking T3 or T4 feedback after thyroid surgery. MATERIAL AND METHODS Three stress questionnaires (Korean version of the Daily Stress Inventory, Social Readjustment Rating Scale, and Stress Overload Scale-Short [SOSS]), an open-ended questionnaire (OQ), and thyroid function tests were administered twice to 106 patients enrolled from January 2019 to October 2020. RESULTS In a multiple generalized linear mixed-effect model (GLMM) involving 106 patients, the T3 and free T4 levels, OQ, body weight, extent of thyroidectomy, and preoperative TSH levels were significantly correlated with log-transformed TSH (lnTSH). The modified SOSS (category) based on recent stressors on OQ interview was significantly associated with lnTSH. In the GLMM with modified SOSS (category), the lnTSH increased by 2.3 and 0.56 in the unconscious high- and high-risk groups, respectively, compared to that in the low-risk group (P<0.05). The calculated power of this study was 0.92 based on alpha=0.05. CONCLUSIONS TSH had a significant relationship with stress and the extent of thyroidectomy. An OQ supported the SOSS to help detect unrecognized stressors. TSH has potential utility as a stress marker combined with the modified SOSS (category) with sufficient power. However, questionnaires on social environments and research on coping strategies for stress are necessary for future studies.

Association between Thyroid Function and Respiratory Distress Syndrome in Preterm Infants

Thyroid hormones are known to influence the production and secretion of pulmonary surfactant. The objective of this study was to explore the relationship between respiratory distress syndrome (RDS) and thyroid hormones. This was a retrospective study of preterm infants at 24−33 weeks gestational age from April 2017 to February 2019. T3, free T4 (fT4), and thyroid-stimulating hormone (TSH) were measured 1, 3, and 6 weeks after birth. Multivariate logistic regression analyses were performed to determine the relationship between RDS and TSH. A total of 146 infants were enrolled. Of these, 60 had RDS, 72 had no RDS, and 14 were excluded. T3 and TSH were lower in the RDS groups (p < 0.05) on the day of birth. Multivariate logistic regression analysis indicated that lower serum TSH levels immediately after birth were associated with a higher incidence of RDS (OR, 0.89; 95% CI, 0.81−0.97). The TSH level was associated with the incidence of RDS. This suggests that suppression of the hypothalamus−pituitary axis function contributes to RDS, which is the result of surfactant deficiency.

A Pilot Study Evaluating the Feasibility of Testing for an Acute Impact of Human Exposure to a Power-line Frequency Magnetic Field on Blood Cortisol and Thyroid-Stimulating Hormone

Numerous studies have been carried out on the potential effects of an extremely low frequency (ELF-0-300 Hz) magnetic field (MF) on human health. However, there is limited data on the effect of a high exposure level to ELF MFs for a prolonged period. Therefore, the objective of this pilot work was to demonstrate the feasibility of a study evaluating the stress hormone concentrations resulting from a 10-min exposure to a 60 Hz MF of several tens of thousands of µT. In this pilot study, human volunteers were thus exposed for the first time to a 60 Hz, 50 mT MF for a duration of 10 min. Stress hormone levels were measured before (once), during (twice) and after (once) this 10-min exposure period. The small sample size (n = 5) did not allow to conduct standard inferential statistical tests and no conclusion regarding the exposure effects can be drawn. However, this study demonstrates the feasibility of using a simple blood testing material in a protocol testing for the effect of a 10-min exposure to a high MF level in healthy human volunteers. © 2022 Bioelectromagnetics Society.

Association between maternal thyroid function and risk of gestational hypertension and preeclampsia

OBJECTIVES

To investigate the influence of maternal level of thyroid-stimulating hormone (TSH), free triiodothyronine (FT3) and free thyroxine (FT4) one by one or in combination on incidence of gestational hypertension and preeclampsia.

METHODS

The study included pregnant women (n=107) hospitalized in the period from July 1, 2020 to October 10, 2021 at the Department of Pathology of Pregnancy of the University Clinic of Obstetrics and Gynecology, University Clinical Center Sarajevo (UCCS) (Bosnia and Herzegovina), due to hypertensive disorder in pregnancy without symptoms of impaired thyroid function. In all patients fulfilling inclusion criteria TSH, FT3, and FT4 using electrochemiluminescence immunoassay (ECLIA, Roche Diagnostics, Basel, Switzerland) were checked. There were two groups of patients: one with gestational hypertension (G1) and the other with preeclampsia (G2). The programs SPSS for Windows 25.0, SPSS Inc, Chicago, IL, USA and Microsoft Excel 11, Microsoft Corporation, Redmond, WA, USA were used for statistical analysis using nonparametric Mann-Whitney U test because the distribution of the data was not normal. The result was considered statistically significant if p<0.05.

RESULTS

Gestational age at delivery (G2 36.86 ± 3.79 vs. G1 38.94 ± 2.15; p=0.002) and birth weight (G2 2,841.36 ± 1,006.39 vs. G2 3,290.73 ± 745.6; p=0,032) were significantly different between the investigated groups. The difference between the peak systolic (p=0.002), peak diastolic blood pressure (p=0.007), TSH (p=0.044), and FT3 (p=0.045) were statistically significant. Impaired thyroid function was observed more often in G2 than in G1.

CONCLUSIONS

Thyroid function was more often affected adversely in pregnancies complicated with preeclampsia than with gestational hypertension. Based on the results of our study it might be prudent to check thyroid hormones in all asymptomatic pregnancies with preeclampsia or gestational hypertension. These findings need confirmation in larger better designed prospective studies.

Associations between Dynamic Vitamin D Level and Thyroid Function during Pregnancy

Optimal Vitamin D (VitD) status and thyroid function are essential for pregnant women. This study aimed to explore associations between dynamic VitD status and thyroid function parameters in each trimester and throughout the pregnancy period. Information on all 8828 eligible participants was extracted from the Peking University Retrospective Birth Cohort in Tongzhou. Dynamic VitD status was represented as a combination of deficiency/sufficiency in the first and second trimesters. Thyroid function was assessed in three trimesters. The associations between VitD and thyroid function were assessed by multiple linear regression and generalized estimating equation models in each trimester and throughout the pregnancy period, respectively. The results indicated that both free thyroxine (fT4; β = 0.004; 95%CI: 0.003, 0.006; p < 0.001) and free triiodothyronine (fT3; β = 0.009; 95%CI: 0.004, 0.015; p = 0.001) had positive associations with VitD status in the first trimester. A VitD status that was sufficient in the first trimester and deficient in the second trimester had a lower TSH (β = −0.370; 95%CI: −0.710, −0.031; p = 0.033) compared with the group with sufficient VitD for both first and second trimesters. In conclusion, the associations between VitD and thyroid parameters existed throughout the pregnancy. Maintaining an adequate concentration of VitD is critical to support optimal thyroid function during pregnancy.

Brain atlas for glycoprotein hormone receptors at single-transcript level

There is increasing evidence that anterior pituitary hormones, traditionally thought to have unitary functions in regulating single endocrine targets, act on multiple somatic tissues, such as bone, fat, and liver. There is also emerging evidence for anterior pituitary hormone action on brain receptors in mediating central neural and peripheral somatic functions. Here, we have created the most comprehensive neuroanatomical atlas on the expression of TSHR, LHCGR, and FSHR. We have used RNAscope, a technology that allows the detection of mRNA at single-transcript level, together with protein level validation, to document Tshr expression in 173 and Fshr expression in 353 brain regions, nuclei and subnuclei identified using the Atlas for the Mouse Brain in Stereotaxic Coordinates. We also identified Lhcgr transcripts in 401 brain regions, nuclei and subnuclei. Complementarily, we used ViewRNA, another single-transcript detection technology, to establish the expression of FSHR in human brain samples, where transcripts were co-localized in MALAT1-positive neurons. In addition, we show high expression for all three receptors in the ventricular region-with yet unknown functions. Intriguingly, Tshr and Fshr expression in the ependymal layer of the third ventricle was similar to that of the thyroid follicular cells and testicular Sertoli cells, respectively. In contrast, Fshr was localized to NeuN-positive neurons in the granular layer of the dentate gyrus in murine and human brain-both are Alzheimer's disease-vulnerable regions. Our atlas thus provides a vital resource for scientists to explore the link between the stimulation or inactivation of brain glycoprotein hormone receptors on somatic function. New actionable pathways for human disease may be unmasked through further studies.

Assessment of Preoperative TSH Serum Level and Thyroid Cancer Occurrence in Patients with AUS/FLUS Thyroid Nodule Diagnosis

Thyroid-stimulating hormone (TSH) is a growth factor associated with the initiation and progression of well-differentiated thyroid cancer (WDTC). Atypia of undetermined significance and follicular lesion of undetermined significance (AUS/FLUS) are the most uncertain cytological diagnoses of thyroid nodules. The aim of the study was to determine the association of histopathological diagnosis with preoperative serum TSH levels in patients with AUS/FLUS thyroid nodule diagnosis. Among 5028 individuals with thyroid nodules, 342 (6.8%) with AUS/FLUS diagnoses were analyzed. The frequency of all histopathology diagnoses was assessed for associations with preoperative serum TSH levels. The median TSH concentration was significantly higher in patients with AUS/FLUS diagnosis and histopathology of WDTC than in patients with the same cytology result and histopathology of a benign tumor (p < 0.0001). The diagnostic potential of serum TSH level was determined to evaluate risk of malignancy in patients with thyroid nodules classified into the Bethesda III category. ROC analysis showed the TSH concentration at a cutoff point of 2.5 mIU/L to be an acceptable prognostic factor for WDTC. For this optimal cutoff point, the AUC was 0.877, the sensitivity was 0.830, and the specificity was 0.902. Preoperative serum TSH levels in patients with AUS/FLUS thyroid tumor diagnosis should be taken into consideration in the decision-making process and clinical management.

Thyroid Hormones Are Not Associated with Plasma Osteocalcin Levels in Adult Population with Normal Thyroid Function

Thyroid hormones (THs) play an indispensable role in skeletal development and bone remodeling. Some studies have reported associations of THs with serum osteocalcin (OC) levels, but the results are quite inconsistent and the molecular mechanism of their simultaneous or interdependent activity on bone is almost unknown. Therefore, the aim of this study was to determine the possible associations of plasma THs with plasma OC levels and the possible mediating effect of OC on the relationship between THs and bone mineral density (BMD). For this purpose, out of the initial 1981 participants, we selected healthy euthyroid participants controlled for available confounding factors that can affect thyroid function and bone metabolism (N = 694). Given our results, we could not confirm any associations of THs with plasma OC levels nor the mediating effect of OC on the relationship between THs and BMD in euthyroid population. In the group of women controlled for menopause status (N = 396), we found a significant negative association of body mass index (BMI) with OC levels (β = −0.14, p = 0.03). We also found a negative association of free triiodothyronine (fT3) (β = −0.01, p = 0.02) and age (β = −0.003, p < 0.001) with BMD, and a positive association of BMI (β = 0.004, p < 0.001) and male gender (β = 0.1, p < 0.001) with BMD. In addition, we found significantly higher plasma OC levels and lower values of BMD in postmenopausal euthyroid women compared with premenopausal euthyroid women. In our opinion, the results of previous studies suggesting an association between circulating THs and serum OC levels may be influenced by an inconsistent selection of participants and the influence of confounding factors.

Radioiodine treatment of hyperthyroidism in cats: results of 165 cats treated by an individualised dosing algorithm in Spain

OBJECTIVES

Although radioiodine (131I) is the treatment of choice for feline hyperthyroidism, 131I-dosing protocols commonly induce iatrogenic hypothyroidism and expose azotaemia. A recently reported patient-specific 131I dosing algorithm minimised the risk of 131I-induced hypothyroidism and azotaemia, while maintaining high cure rates. The aim of the study was to report results of 131I treatment in a European population of hyperthyroid cats using this patient-specific dosing algorithm.

METHODS

This prospective case series (before-and-after study) evaluated 165 hyperthyroid cats referred for 131I treatment. All cats had serum concentrations of thyroxine (T4), triiodothyronine (T3) and thyroid-stimulating hormone (TSH) measured (off methimazole ⩾1 week). Thyroid volume and percentage uptake of 99mTc-pertechnetate (TcTU) were determined using thyroid scintigraphy. An initial 131I dose was calculated by averaging dose scores for T4/T3 concentrations, thyroid volume and TcTU; 70% of that composite dose was then administered. Twenty-four hours later, percentage 131I uptake was measured, and additional 131I administered as needed to deliver an adequate radiation dose to the thyroid tumour(s). Serum concentrations of T4, TSH and creatinine were determined 6-12 months later.

RESULTS

Median calculated 131I dose was 2.15 mCi (range 1.2-7.5), with only 51 (30.9%) receiving ⩾2.5 mCi. Of 165 cats, 124 (75.2%) became euthyroid, seven (4.2%) became overtly hypothyroid, 27 (16.4%) became subclinically hypothyroid and seven (4.2%) remained hyperthyroid. A higher proportion of overtly (85.7%) and subclinically (26.9%) hypothyroid cats developed azotaemia than euthyroid cats (13.6%; P = 0.0002). Hypothyroid cats were older (P = 0.016) and more likely to have detectable TSH concentrations (P = 0.025) and symmetrical bilateral distribution of 99mTc-pertechnetate uptake (P = 0.0002), whereas persistently hyperthyroid cats had higher severity scores (P = 0.012).

CONCLUSIONS AND RELEVANCE

Our results confirm that 131I dosing with this new algorithm results in high cure rates, with a lowered prevalence of 131I-induced overt hypothyroidism and azotaemia. Age, serum TSH concentrations, bilateral, symmetrical uptake and severity score help predict outcome.

[Influence of intranasally administered insulin on metabolic and hormonal parameters in adult male rats, impaired due to three-day fasting in the early postnatal period]

Temporary cessation or restriction of breastfeeding can lead to metabolic disorders in adulthood. However, data on the effect of fasting in the early postnatal period on the functions of the endocrine system in adulthood are rare and contradictory. Approaches for the correction of metabolic and hormonal disorders caused by premature cessation of breastfeeding have not been developed yet. The aim of the work was to study the metabolic and hormonal parameters and changes in the hormonal status of the gonadal and thyroid systems in 10-month-old male rats with interruption of breastfeeding on days P19-P21, as well as to evaluate the restorative effect on them of four weeks of treatment with intranasal insulin (II) administered in the postnatal period (P28-P55) or in adulthood (P183-P210). Lactation interruption has been induced by treatment of lactating females with bromocriptine (10 mg/day/rat, P19-P21). Male rats with temporary cessation of breastfeeding developed characteristic signs of the metabolic syndrome (obesity, dyslipidemia, impaired glucose tolerance, hyperleptinemia), decreased levels of testosterone and thyroid hormones (fT4, tT3) and weakened the synthesis of testosterone and thyroxine, stimulated respectively by GnRH and thyroliberin. This was due to a decrease in the sensitivity of the testes to luteinizing hormone (LH) and the thyroid gland to thyroid-stimulating hormone (TSH). Treatment with II in early ontogenesis reduced body weight and fat, improved lipid profile, sensitivity to insulin, leptin, LH and TSH, restored the levels of testosterone and thyroid hormones and their stimulation by releasing factors. Treatment with II in adulthood normalized the levels of testosterone, thyroid hormones, their stimulation by releasing factors, but had a little effect on metabolic and hormonal parameters. The obtained data point to a wide range of metabolic and hormonal disorders in adult male rats with the "neonatal" model of metabolic syndrome and to the effectiveness of various strategies for their correction using long-term II treatment.

Economic and Cardiometabolic Risk Factors Are Predictors of Lower Thyroid Stimulating Hormone (TSH) Levels in Hispanic/Latinx Adults with Euthyroidism-A Community-Based Study

Thyroid hormone abnormalities are among the most common endocrine disorders comorbidly suffered alongside metabolic syndrome and type 2 diabetes mellitus (T2DM), and within the euthyroid range they may also impact other outcomes, such as mood disorders. This study aimed to observationally examine the relationship between TSH and social determinants of health and clinical measures in a euthyroid Hispanic/Latinx patient sample with a diagnosis of anxiety and/or depression disorders from a community health clinic. A needs assessment was completed using a random sample of 100 de-identified medical records of individuals who received free medical care, including mental health, at a community-based clinic. Those with low normal TSH (<2 mIU/L) compared with high normal TSH (≥2 mIU/L) had a greater odds of food insecurity (p = 0.016) and being at 100% of the federal poverty level (p = 0.015). The low normal TSH group had significantly higher fasting glucose (p = 0.046), hemoglobin A1c (p = 0.018), and total cholesterol (p = 0.034) compared with the high normal TSH group. In those with T2DM, individuals with low normal TSH had six-times greater odds of having high fasting glucose (p = 0.022) and high hemoglobin A1c (p = 0.029). These relationships warrant further study, to inform future public health policies and follow-up care for underserved and vulnerable communities.

Thyroid-Stimulating Hormone and Thyroid Hormones and Incidence of Diabetes: Prospective Results of the Brazilian Longitudinal Study of Adult Health (ELSA-BRASIL)

Background: There are conflicting data regarding the association of thyroid function with incident diabetes. We prospectively investigated thyrotropin (TSH), free thyroxine (fT4), free triiodothyronine (fT3), and its conversion ratio (fT3:fT4) with the risk of developing diabetes in euthyroid subjects and those with subclinical thyroid dysfunction. Our hypothesis is that this relationship is a U-shaped curve since both subclinical thyroid diseases may be associated with diabetes. Methods: ELSA-Brasil is a highly admixed cohort study of 35-74 years old at baseline (2008-2010). Levels of TSH, fT4, fT3, and fT3:fT4 ratio were evaluated at baseline and incident diabetes was estimated over an 8.2-year follow-up (2017-2019). Diabetes was identified based on medical diagnosis, prescriptions, and laboratory tests. The risk of diabetes was evaluated according to quintiles of TSH, fT4, fT3, and fT3:fT4 ratio using Poisson regression with robust variance presented as relative risk (RR) with confidence interval [CI] of 95% after multivariable adjustment for sociodemographic and cardiovascular risk factors (reference third quintile), and as continuous variables. Results: We included 7948 participants (mean age, 50.2 [standard deviation 8.6] years; 54.4% female): 7177 euthyroid, 726 with subclinical hypothyroidism, and 45 with subclinical hyperthyroidism. Incidence of diabetes was 14.8%. No association was found for TSH, fT4, fT3, and fT3:fT4 ratio quintiles with incident diabetes. Using continuous variables, the increase of 1-unit (1-U) of fT4 decreased the risk of diabetes (RR 0.94 [CI 0.91-0.99]), while the increase of 1-U of the fT3:fT4 ratio increased the diabetes risk (RR 1.37 [CI 1.15-1.63]). The increase of 1-U of fT3 was associated with an increased risk of diabetes, but without significance after multivariable adjustment. In body mass index-stratified analysis, people with overweight or obesity presented a modest significantly higher risk of diabetes in the lowest quintile of fT4 (RR 1.04 [CI 1.01-1.07]) and an inverse association with incident diabetes in the first quintile of fT3:fT4 ratio (RR, 0.95 [CI 0.93-0.98]). The analyses using continuous variables presented similar findings. Conclusion: These findings suggest that fT4 and fT3 levels and the conversion rate might be additional risk factors associated with incident diabetes, especially in the presence of overweight or obesity. However, they need to be confirmed in future studies. (ClinicalTrials.gov Identifier: NCT02320461).

Serum thyroid-stimulating hormone is an independent risk factor of recurrent Guillain-Barré syndrome

INTRODUCTION/AIMS

Guillain-Barré syndrome (GBS) is generally considered to be monophasic, but some patients have recurrences. The purpose of this study was to clarify the possible link between thyroid parameters and recurrent GBS (RGBS) patients in China.

METHODS

In this retrospective study we enrolled patients who were admitted to the Department of Neurology of The First Affiliated Hospital of Zhengzhou University from 2014 to 2020 and fulfilled the diagnostic criteria of GBS or Miller Fisher syndrome. We evaluated clinical characteristics; cerebrospinal fluid parameters; and serum levels of thyroid-stimulating hormone (TSH), free thyroxine, and free triiodothyronine in 320 individuals, including 302 with monophasic GBS and 18 with recurrent GBS.

RESULTS

Serum levels of TSH in monophasic GBS patients were significantly lower than those in RGBS patients (P < .001), whereas FT3 levels were higher in the monophasic GBS group (P = .022). Age at onset, incidence of antecedent illness, time from onset to nadir, proportion with acute inflammatory demyelinating polyradiculoneuropathy, and Hughes Functional Grading Scale score at nadir were statistically significant between monophasic GBS patients and RGBS patients (P < .05). The multivariate regression analysis revealed that antecedent illness, AIDP, and high TSH were independent risk factors for RGBS. Our receiver-operating characteristic curve analysis showed that the risk of recurrence in GBS patients increases when the TSH concentration is higher than 3.87 μIU/mL.

DISCUSSION

Our results demonstrate an association between TSH and RGBS. Oxidative stress is one of the possible interpretations for this association.

Thyroid Function and the Risk of Prediabetes and Type 2 Diabetes

CONTEXT

Thyroid hormones are important regulators of glucose metabolism, and studies investigating the association between thyroid function and type 2 diabetes incidence have shown conflicting results.

OBJECTIVE

We aimed to combine the evidence from prospective studies addressing the association between thyroid function and type 2 diabetes risk.

METHODS

We systematically searched in Embase, Medline (Ovid), Web of Science, Cochrane, and Google Scholar for prospective studies assessing the association of thyroid function and incident type 2 diabetes. Data extraction was performed using a standardized protocol by 2 independent reviewers. We assessed study quality using the Newcastle-Ottawa Scale and pooled hazard ratios (HRs) and 95% CI using random-effects models.

RESULTS

From the 4574 publications identified, 7 met our inclusion criteria and were included in the qualitative synthesis. Six publications were included in the meta-analysis. Studies assessed hypothyroidism (6 studies), hyperthyroidism (5 studies), thyrotropin (TSH) in the reference range (4 studies), and free thyroxine (FT4) in the reference range (3 studies) in relation to incident type 2 diabetes. The pooled HR for the risk of type 2 diabetes was 1.26 (95% CI, 1.05-1.52) for hypothyroidism, 1.16 (95% CI, 0.90-1.49) for hyperthyroidism, 1.06 (95% CI, 0.96-1.17) for TSH in the reference range, and 0.95 (95% CI, 0.91-0.98) for FT4 in the reference range.

CONCLUSION

Current evidence suggests an increased type 2 diabetes risk in people with hypothyroidism and lower FT4 levels in the reference range. Further population-based studies are needed to address this association given the limited evidence.

The Changes of Thyroid Function and Related Factors in Critical Patients without Thyroid Illness in ICU: A Retrospective Cross-Sectional Study

Objective

To retrospectively analyze the changes of thyroid function and related factors in critical patients with non-thyroid illness, hoping to find some indicators for the further examination of the thyroid function in the intensive care unit situation.

Methods

The clinical data of 52 patients admitted to the ICU of Fuzhou First Hospital in Fujian Province, China, from May 2018 to March 2019 were collected. Patients were allocated into the central hypothyroidism group (CH group, n = 21) and the low T3 syndrome group (LT3S group, n = 31) based on thyroid function. All related medical data were collected, and the correlations between variables were identified using Spearman's or Pearson's rank correlation coefficients.

Results

The Acute Physiology and Chronic Health Evaluation (APACHE) II score in the CH group and the LT3S group were 20.6 ± 3.6 and 19.3 ± 3.6, respectively, measured within 24 hours following hospital admission. The mean value of thyroid-stimulating hormone (TSH) in the CH group (0.3 ± 0.3 IU/mL) was significantly lower than that in the LT3S group (1.7 ± 0.9 IU/mL), P < 0.001. Fasting plasma glucose (FPG) level in the CH group was significantly higher than that in the LT3S group (10.3 ± 5.0 mmol/L vs 6.8 ± 2.5 mmol/L, P = 0.002).

Conclusion

Central hypothyroidism may exist in critically ill patients and may be associated with elevated fasting plasma glucose levels; accordingly, it should be included as part of patient assessment. When FPG is higher than 6.4mmol/L on admission, thyroid function should be actively examined.