Impact of metformin on hypothalamic-pituitary-thyroid axis activity in women with autoimmune and non-autoimmune subclinical hypothyroidism: a pilot study

BACKGROUND

Metformin reduces plasma TSH levels if these levels are elevated. No study has investigated whether the hormonal effects of metformin are impacted by thyroid autoimmunity. The current study aimed to compare the effect of metformin on hypothalamic-pituitary-thyroid axis activity between subjects with mild hypothyroidism of different origins.

METHODS

The study population consisted of two groups of women with prediabetes and mildly elevated TSH levels, matched by age, insulin sensitivity, TSH, and thyroid hormone levels. Group A included 26 women with autoimmune thyroiditis, while group B enrolled 26 individuals with hypothyroidism of non-autoimmune origin. Both groups were treated with metformin (2.55-3 g daily). Circulating levels of TSH, total and free thyroid hormones, glucose, insulin, prolactin, high-sensitivity C-reactive protein (hsCRP) and 25-hydroxyvitamin D, concentrations of thyroid antibodies, and structure parameters of thyroid homeostasis were assessed at baseline and 6 months later.

RESULTS

All patients completed the study. At baseline, both groups differed in concentrations of thyroid peroxidase antibodies, thyroglobulin antibodies, hsCRP, and 25-hydroxyvitamin D. The drug reduced TSH and Jostel's index, with no difference between the study groups. The improvement in insulin sensitivity, observed in both groups, was more pronounced in group B than in group A. In women with autoimmune hypothyroidism, the drug increased SPINA-GT and decreased hsCRP levels. The remaining markers did not change throughout the study.

CONCLUSIONS

The obtained results suggest that, despite differences in thyroid output, the impact of metformin on TSH levels is similar in hypothyroid women with and without thyroid autoimmunity.

Interference against a newly labeled substance with ruthenium sulfonate complexes showing discrepant thyroid function test results

We report here two patients exhibiting a combination of falsely elevated serum levels of free thyroxine (FT4), free triiodothyronine (FT3), and thyrotropin receptor antibodies (TRAb), measured using Elecsys assay kits (Roche Diagnostics GmbH). The first patient was a 74-year-old man misdiagnosed with Graves' disease and treated with methimazole. The second patient was a 48-year-old woman whose serum FT4 and FT3 concentrations were found to be high during a blood test. These patients denied taking biotin or any other supplements. Further detailed examination, including a heterophilic blocking tube test, revealed the presence of serum antibodies. The abnormal reactions were observed only using the improved assay kits using ruthenium (Ru) sulfonate instead of Ru as a chemiluminescent agent. Therefore, serum antibodies to the Ru sulfonate complex caused the pseudo-high levels of FT4, FT3, and TRAb. To our knowledge, this is the first report showing that antibodies to the Ru sulfonate complex in the electrochemiluminescence immunoassay can cause falsely elevated levels of the combination, leading to discrepant thyroid function test results. We emphasize that in cases of abnormal test results, alternative assay methods should be considered for further examination; unusual test results should not be impulsively interpreted, even when using revised assay kits.

One children's hospital planning and development process to adhere to the FDA recommendation that babies and young children undergo thyroid function testing after receiving an injection of iodine-containing contrast media for medical imaging

The United States (US) Food and Drug Administration (FDA) has issued multiple statements and guidelines since 2015 on the topic of thyroid function testing in babies and children through 3 years old after receiving iodinated contrast media for medical imaging exams. In April 2023, the FDA adjusted this recommendation to target babies and young children younger than 4 years of age who have a history of prematurity, very low birth weight, or underlying conditions which affect thyroid gland function, largely in response to solid arguments from expert statements from the American College of Radiology (ACR) which is endorsed by the Society for Pediatric Radiology (SPR), Pediatric Endocrinology Society (PES), and the Society for Cardiovascular Angiography & Intervention (SCAI). Herein we describe our approach and development of a clinical care guideline along with the steps necessary for implementation of the plan including alterations in ordering exams requiring iodinated contrast media, automatic triggering of lab orders, reporting, and follow-up, to address the 2022 FDA guidance statement to monitor thyroid function in children after receiving iodinated contrast media. The newly implemented clinical care guideline at Ann and Robert H. Lurie Children's Hospital of Chicago remains applicable following the 2023 updated recommendation from the FDA. We will track patients less than 3 months of age who undergo thyroid function testing following computed tomography (CT), interventional radiology, and cardiac catheterization exams for which an iodinated contrast media is administered as a clinical care quality initiative.

Exploring the Association between Thyroid Function and Frailty: Insights from Representative Korean Data

BACKGRUOUND

This study investigates the association between thyroid function and frailty in the old patients using representative data.

METHODS

The study was conducted using data from the Korea National Health and Nutrition Examination Survey conducted from 2013 to 2015. The study population included 2,416 participants aged 50 years and older with available thyroid function test data. Frailty assessment was performed using the Fried frailty phenotype. The prevalence of frailty was analyzed across different thyroid diseases and thyroid function parameters.

RESULTS

The significant association between thyroid dysfunction and frailty was observed in overt hyperthyroidism and subclinical hyperthyroidism. After adjusting for various factors, the association between thyroid dysfunction and frailty remained significant. On the other hand, overt hypothyroidism did not show a significant association with frailty in the adjusted analysis. For individuals with overt hyperthyroidism and subclinical hyperthyroidism, higher levels of free thyroxine (FT4) were significantly associated with an increased risk of frailty (aOR >999; 95% CI, >999 to 999). Among individuals with overt hypothyroidism, lower level of FT4 levels and high thyrotropin (TSH) levels showed a significant association with frailty risk (FT4: aOR, <0.01; TSH: aOR, 999). In participants with subclinical hypothyroidism, there were no significant associations between parameters for thyroid and frailty risk.

CONCLUSION

These findings suggest that thyroid dysfunction, particularly overt hyperthyroidism and subclinical hyperthyroidism, may be associated with an increased risk of frailty in the old patients.

Prospective study of thyroid function in the first year of life in infants with Down syndrome

Current American Academy of Pediatrics (AAP) Guidelines recommend monitoring thyroid function in infants with Down syndrome (DS) at birth, 6 and 12 months, and annually thereafter. This study aimed to determine whether these guidelines are optimal for early diagnosis and treatment of (subclinical) hypothyroidism. Enrolled infants with DS less than age 7 months, born at ≥ 30 weeks gestation to monitor thyroid function test (TFT). A filter paper (FP) blood sample was analyzed for TSH and total T4 at ages 2 and 4 weeks and monthly thereafter until 12 months. Subjects with abnormal FP sample and confirmatory serum TFT for hypothyroidism promptly started treatment. Subjects with thyroid dysfunction identified had thyroid antibodies measured at diagnosis and 12 months. Descriptive statistics determined average time to diagnosis of abnormal TFT. Sixteen (30%) of 54 subjects were diagnosed with a thyroid disorder, the majority with subclinical hypothyroidism (SH) and 1 with hyperthyroidism. Diagnosis occurred in 6 (11%), 9 (17%), and 12 (22.2%) infants in the first 30, 60, and 90 days of life (DOL), respectively. Eight infants had an abnormal NBS and half were diagnosed with a thyroid disorder by DOL 8 and the remainder prior to 4 months. Among subjects with a normal NBS, four were diagnosed at a mean of 104 days and three at a mean of 101 days prior to the 6-month and 12-month routine screens, respectively.  Conclusion: Based on current AAP guidelines, thyroid disorder diagnosis would have been delayed in nearly 20% of the subjects. An additional TFT screen at 1 and 3 months can lead to earlier diagnosis and treatment. What is Known: • Current American Academy of Pediatrics (AAP) Guidelines recommend thyroid function tests (TFT) in infants with Down syndrome (DS) at birth and 6 and 12 months. • Peer- reviewed retrospective studies report an increased incidence of hypothyroidism in infants with DS undetected by the newborn screen (NBS) and prior to 6 months. What is New: • This prospective study monitored TFT in infants with DS at age 2 weeks and monthly throughout the first year of life. • The findings in this study support additional TFT screens at 1 and 3 months in infants with DS.

The impact of covid-19 on thyroid function tests in pregnancy

PURPOSE

To investigate the effects of laboratory-confirmed SARS-CoV-2 infection on thyroid function tests (TFTs) in pregnant women and to evaluate whether TFT changes are related to the severity and prognosis.

METHODS

Consecutive pregnant women tested for SARS-CoV-2 by RT-PCR at Ankara City Hospital were recruited between January 2021 and September 2021. Thyroid-stimulating hormone (TSH), free thyroxine (FT4) and free triiodothyronine (FT3), thyroid peroxidase antibody (anti-TPO), and thyroglobulin antibody (anti-TG) were measured on admission.

RESULTS

Among 747 eligible pregnant women with the same baseline characteristics, 369 RT-PCR-positive women in the patient group and 378 RT-PCR-negative women in the control group were included in the analyses. Pregnant women in the patient group had significantly lower TSH, FT4, FT3, Anti TPO, and Anti TG concentrations compared with those in the control group (p < 0.001). The proportion of patient groups with mild, moderate, severe, and critical diseases were 297 (80.4%), 40 (10.8%), 17 (4.6%), and 15 (4.2%), respectively, among which with the moderate, severe, and critical disease had significantly lower FT3 values (2.5 vs 2.19 pg/mL, p < 0.001) and higher nonthyroidal illness syndrome (NTIS) (29.2 vs. 8.4%, p < 0.001) than those with mild disease. Lower FT3 values increased the risk of ICU admission, NICU admission, and severe disease (p < 0.001). FT3 and TSH correlated positively with lymphocytes (p < 0.001) and negatively correlated with C-reactive protein (CRP) (p < 0.001, p = 0.005).

CONCLUSION

The SARS-CoV-2 infection seems to have an impact on the TFTs of pregnant women, and particularly FT3 level seems to be correlated with disease severity.

Development of a prediction score (ThyroCOVID) for identifying abnormal thyroid function in COVID-19 patients

PURPOSE

Thyroid dysfunction in COVID-19 carries clinical and prognostic implications. In this study, we developed a prediction score (ThyroCOVID) for abnormal thyroid function (TFT) on admission amongst COVID-19 patients.

METHODS

Consecutive COVID-19 patients admitted to Queen Mary Hospital were prospectively recruited during July 2020-May 2021. Thyroid-stimulating hormone (TSH), free thyroxine (fT4) and free triiodothyronine (fT3) were measured on admission. Multivariable logistic regression analysis was performed to identify independent determinants of abnormal TFTs. ThyroCOVID was developed based on a clinical model with the lowest Akaike information criteria.

RESULTS

Five hundred and forty six COVID-19 patients were recruited (median age 50 years, 45.4% men, 72.9% mild disease on admission). 84 patients (15.4%) had abnormal TFTs on admission. Patients with abnormal TFTs were more likely to be older, have more comorbidities, symptomatic, have worse COVID-19 severity, higher SARS-CoV-2 viral loads and more adverse profile of acute-phase reactants, haematological and biochemical parameters. ThyroCOVID consisted of five parameters: symptoms (malaise), comorbidities (ischaemic heart disease/congestive heart failure) and laboratory parameters (lymphocyte count, C-reactive protein, and SARS-CoV-2 cycle threshold values). It was able to identify abnormal TFT on admission with an AUROC of 0.73 (95% CI 0.67-0.79). The optimal cut-off of 0.15 had a sensitivity of 75.0%, specificity of 65.2%, negative predictive value of 93.5% and positive predictive value of 28.1% in identifying abnormal TFTs on admission amongst COVID-19 patients.

CONCLUSION

ThyroCOVID, a prediction score to identify COVID-19 patients at risk of having abnormal TFT on admission, was developed based on a cohort of predominantly non-severe COVID-19 patients.

Thyroid Dysfunction from Treatments for Solid Organ Cancers

In recent years, cancer care has been transformed by immune-based and targeted treatments. Although these treatments are effective against various solid organ malignancies, multiple adverse effects can occur, including thyroid dysfunction. In this review, the authors consider treatments for solid organ cancers that affect the thyroid, focusing on immune checkpoint inhibitors, kinase inhibitors, and radioactive iodine-conjugated treatments (I-131-metaiodobenzylguanidine). They discuss the mechanisms causing thyroid dysfunction, provide a framework for their diagnosis and management, and explore the association of thyroid dysfunction from these agents with patient survival.

Differences in thyroid function tests after administration of a single supraphysiological dose of ACTH or a high dose of a synthetic steroid

OBJECTIVE

Although the suppressive action of synthetic steroids on the hypothalamus-pituitary-thyroid (HPT) axis is established, little is known regarding the effect of the administration of synthetic adrenocorticotropic hormone (ACTH).

DESIGN

In the context of a randomized, open label, comparative study assessing the efficacy and safety of ACTH and betamethasone in the treatment of hospitalized patients with acute gout, we compared the effects of these agents on thyroid function tests.

METHODS

Serum TSH, total T4 and T3 and cortisol were measured before and at 24 and 48 h after a single intramuscular dose of synthetic ACTH (1 mg) or betamethasone (6 mg), in 38 hospitalized patients with acute gout and normal thyroid function.

RESULTS

The final analysis included 32 patients, due to missing data. The ACTH and betamethasone groups did not differ regarding the mean age, gender, severity of gout attack, and baseline thyroid parameters. In the ACTH group TSH and T4 were significantly decreased at 24 and at 48 h compared to baseline, while T3 was decreased at 24 but not at 48 h. In the betamethasone group T3 remained stable; TSH and T4 decreased significantly from baseline levels at 24 h; at 48 h, TSH had returned to and T4 showed a partial rebound towards pre-treatment values.

CONCLUSIONS

A single IM administration of 1 mg of synthetic ACTH has more profound and prolonged effects on the HPT axis, lasting for at least 48 h, compared to a single IM dose of 6 mg betamethasone.

The potential impact of COVID-19 on thyroid gland volumes among COVID-19 survivors

PURPOSE

Data about the effects of COVID-19 on the endocrine system are increasing over time. In the present study, we investigated the effects of COVID-19 on the thyroid gland among COVID-19 survivors by comparing them with healthy subjects.

METHODS

Adult COVID-19 survivors who were managed and followed up in the Infectious Disease clinic were asked to participate in this study. COVID-19 survivors were recruited via a convenience sampling and those who agreed to participate in this study were seen by endocrinologists for assessments. The blood tests were obtained for thyroid antibodies and thyroid function tests. Thyroid ultrasonography (USG) was done by the same physician. The ellipsoid formula was used for the calculation of thyroid gland volume.

RESULTS

64 adult COVID-19 survivors and 70 control subjects were enrolled in the study. The COVID-19 survivors were evaluated at median 5.7 months (IQR: 4-6.5) (range: 2-7 months) after acute infection. The mean thyroid gland volume was significantly lower in COVID-19 survivors (10.3 ± 3.4 mL) than in the controls (14 ± 5.3 mL) (p = 0.001). There was no significant difference in free triiodothyronine (fT3), free thyroxine (fT4) and thyroid-stimulating hormone (TSH) levels between the groups. Among the twelve patients who had thyroid function evaluated in acute COVID-19, fT3 values were lower in acute COVID-19 than at the time of USG evaluation (3.04 ± 0.41 vs 3.47 ± 0.31 pg/mL), (p = 0.02). Among COVID-19 survivors, mild TSH elevation was detected in 4 (6.2%) patients and all of the other COVID-19 survivors (93.7%) were euthyroid.

CONCLUSIONS

At 6 months after acute COVID, COVID-19 survivors had smaller thyroid gland volume than healthy controls, and only a few of the COVID-19 survivors had abnormal thyroid function.

Association of Salt Iodization and Urine Iodine Concentration in Schoolchildren from Public Schools in Northeast of Brazil

Iodine deficiency (ID) is recognized as a leading risk factor for child development. Universal salt iodization (USI) is an effective and well-established intervention strategy for the prevention of iodine deficiency disorders (IDD). To evaluate the levels of iodine in household salt samples and the urinary iodine concentration (UIC) in schoolchildren aged 6 to 14 years in public schools in Bahia, Brazil. A cross-sectional study was conducted with 1231 students (6 to 14 years old) from 17 public schools in Bahia. The iodine concentration was evaluated in salt and UIC samples. The adapted Sandell-Kolthoff reaction was used to determine urinary iodine levels. A spectrophotometer (UV-Vis) was used to examine the reduction of ceric ammonium sulfate. A standard iodine solution using a potassium iodate was used to extrapolate the iodine concentrations. The total of 665 salt samples had a median iodine concentration of 24 mg/kg (25th-75th percentile 17.0 to 28.5 mg/kg). The largest proportion (79.6%) of salt samples had iodine concentration in the recommended range, 17.6% of the samples presented iodine at a salt concentration below the established level (<15 mg/kg) and a small proportion was above it (2.8%). The general mean urinary iodine concentration (MUIC) was 217.53 ± 28.30 μg/L and median was 205.50 μg/L. The students evaluated and the salt samples analyzed showed satisfactory results, as recommended by Brazilian legislation and nutritional recommendations of the World Health Organization (WHO).

Higher SARS-CoV-2 viral loads correlated with smaller thyroid volumes on ultrasound among male COVID-19 survivors

PURPOSE

Thyroid dysfunction, including thyroiditis, is well recognized in COVID-19 patients. We evaluated thyroid ultrasonographic features among COVID-19 survivors, which are less well known.

METHODS

Adult COVID-19 survivors without known thyroid disorders who attended dedicated COVID-19 clinic underwent thyroid ultrasonography and assessment of thyroid function and autoimmunity. Adults admitted for acute non-thyroidal surgical problems and negative for COVID-19 were recruited as control. SARS-CoV-2 viral load (VL) was presented as the inverse of cycle threshold values from the real-time reverse transcription-polymerase chain reaction of the respiratory specimen on admission.

RESULTS

In total, 79 COVID-19 patients and 44 non-COVID-19 controls were included. All abnormal thyroid function tests during acute COVID-19 recovered upon follow-up. Thyroid ultrasonography was performed at a median of 67 days after acute COVID-19. The median thyroid volume was 9.73 mL (IQR: 7.87-13.70). In multivariable linear regression, SARS-CoV-2 VL on presentation (standardized beta -0.206, p = 0.042) inversely correlated with thyroid volume, in addition to body mass index at the time of ultrasonography (p < 0.001). Sex-specific analysis revealed similar results among men but not women. Eleven COVID-19 patients (13.9%) had ultrasonographic changes suggestive of thyroiditis, comparable to non-COVID-19 patients (p = 0.375). None of these 11 patients had isolated low thyroid-stimulating hormone levels suggestive of thyroiditis at initial admission or the time of ultrasonography.

CONCLUSIONS

Higher SARS-CoV-2 VL on presentation were associated with smaller thyroid volumes, especially in men. Further research is suggested to investigate this possible direct viral effect of SARS-CoV-2 on the thyroid gland. There was no increased rate of ultrasonographic features suggestive of thyroiditis in COVID-19 survivors.

Effect of acute and chronic liver diseases on the thyroid function in children

BACKGROUND

Thyroid hormones modulate hepatic function through regulation of basal metabolic rate in addition; the liver metabolizes the thyroid hormones and regulates their endocrine effects.

OBJECTIVES

To assess thyroid functions in children with acute and chronic liver diseases.

METHODS

85 studied children were divided into 4 groups; group 1 (20 children) with acute hepatitis (AH), group 2 (20 children) chronic liver disease1 (CLD1; relatively preserved liver functions including Child-Pugh stage A), group 3 (20 children) chronic liver disease2 (CLD2; includes Child-Pugh stage B or C), group 4 (25 children) controls. All groups were subjected to detailed history, physical examination, Complete blood count, liver, renal function tests, viral markers, and thyroid functions (FT3, FT4, TSH).

RESULTS

Free T3 levels were lower in children with AH, CLD1 and CLD2. There was significant increase in TSH serum levels in CLD2.In acute hepatitis a negative correlation between serum free T4 and AST (r = -0.991), positive correlation between serum TSH and AST, VLDL, and cholesterol levels (r= 0.503, 0.533 and 0.498). A positive correlation between free T3 levels and prothrombin concentration (r= 0.991). Negative correlations between free T3 levels and PT, serum bilirubin and LDL serum levels in children with CLD2 (r= -0.992) (r= -0.902) and (r= -0.946) CONCLUSION: Acute and chronic liver diseases affect thyroid function in children and is correlated with the disease severity.

Interpretative commenting in clinical chemistry with worked examples for thyroid function test reports

Correct interpretation of pathology results is a requirement for accurate diagnosis and appropriate patient management. Clinical Pathologists and Scientists are increasingly focusing on providing quality interpretative comments on their reports and these comments are appreciated by clinicians who receive them. Interpretative comments may improve patient outcomes by helping reduce errors in application of the results in patient management. Thyroid function test (TFT) results are one of the areas in clinical chemistry where interpretative commenting is practised by clinical laboratories. We have provided a series of TFT reports together with possible interpretative comments and a brief explanation of the comments. It is felt that this would be of help in setting up an interpretative service for TFTs and also assist in training and continuing education in their provision.

Association between Iodine Intake, Thyroid Function, and Papillary Thyroid Cancer: A Case-Control Study

BACKGROUND

This study aimed to assess the effects of iodine intake, thyroid function, and their combined effect on the risk of papillary thyroid cancer (PTC) and papillary thyroid microcarcinoma (PTMC).

METHODS

A case-control study was conducted including 500 community-based controls who had undergone a health check-up, and 446 overall PTC cases (209 PTC and 237 PTMC) from the Thyroid Cancer Longitudinal Study. Urinary iodine concentration (UIC), was used as an indicator of iodine intake, and serum for thyroid function. The risk of PTC and PTMC was estimated using unconditional logistic regression.

RESULTS

Excessive iodine intake (UIC ≥220 μg/gCr) was associated with both PTC (odds ratio [OR], 18.13 95% confidence interval [CI], 8.87 to 37.04) and PTMC (OR, 8.02; 95% CI, 4.64 to 13.87), compared to adequate iodine intake (UIC, 85 to 219 μg/gCr). Free thyroxine (T4) levels ≥1.25 ng/dL were associated with PTC (OR, 1.97; 95% CI, 1.36 to 2.87) and PTMC (OR, 2.98; 95% CI, 2.01 to 4.41), compared to free T4 levels of 0.7 to 1.24 ng/dL. Individuals with excessive iodine intake and high free T4 levels had a greatly increased OR of PTC (OR, 43.48; 95% CI, 12.63 to 149.62), and PTMC (OR, 26.96; 95% CI, 10.26 to 70.89), compared to individuals with adequate iodine intake and low free T4 levels.

CONCLUSION

Excessive iodine intake using creatinine-adjusted UIC and high free T4 levels may have a synergistic effect on PTC and PTMC. Considering both iodine intake and thyroid function is important to assess PTC and PTMC risk.

Development of a risk prediction model for early discrimination between permanent and transient congenital hypothyroidism

OBJECTIVE

To develop a risk prediction model for early discrimination between transient and permanent congenital hypothyroidism (CH).

DESIGN AND SETTING

In a retrospective cohort, 1047 confirmed CH neonates, from 15 randomly selected provinces in Iran, were entered to the study. Clinical and biochemical information of transient and permanent cases, distinct at the age of 3 years were retrospectively gathered.

RESULTS

Among CH neonates, the overall prevalence of permanent CH was 57.1%. Using forward stepwise multivariable logistic regression analysis, confirmatory venous TSH, total T4 < 8.2 ng/dl, requiring levothyroxine dosage increase, venous TSH ≥ 10 mU/l between 6 and 12 months of age, parental consanguinity and family history of thyroid diseases were associated with increased risk of permanent CH. The prediction model achieved a very good power in discriminating patients with transient and permanent CH with an optimism-corrected area under the ROC curve of 0.86 (95% CI:0.84-0.88) with a very good calibration. Integrated discrimination improvement (IDI) test indicated significantly greater diagnostic performance of the model compared to serum TSH alone.

CONCLUSIONS

Using several potential predictors for permanent CH, we developed a relatively powerful risk prediction model as a cost-saving screening tool in order to avoid unnecessary long-term treatment of transient cases which might empower clinicians for prognostication of the CH course and tailoring treatment up to 1 year of age.

Falsely diagnosed thyrotoxicosis caused by anti-streptavidin antibodies and pre-wash procedures

Background

Anti-streptavidin antibodies are causal determinants of analytical interference during Thyroid function tests, and numerous reports have detailed such interference, with anti-streptavidin antibodies attracting attention.

Case presentation

We conducted a straightforward investigation of interference due to anti-streptavidin antibodies, with a case of a 60-year-old Japanese man who consulted our department for inconsistencies between his clinical course and Thyroid function tests. Experiments were conducted using Cobas8000 e602, which employs assay procedures with pre-wash to evaluate FT4 and FT3 levels.

Conclusions

To our knowledge, this is the first published report to clearly investigate such interferences using a combination of polyethylene glycol precipitation, heterophilic blocking tube precipitation, streptavidin-coated magnetic particle precipitation, and different instruments with or without pre-wash. Clinicians should consider that interferences caused by anti-streptavidin antibodies could lead to a misdiagnosis of thyrotoxicosis. Moreover, discussions between laboratory specialists, clinicians, and manufacturers are required to identify interferences and avoid unnecessary examinations and inappropriate treatment.

Insights from a Prospective Follow-up of Thyroid Function and Autoimmunity among COVID-19 Survivors

BACKGROUND

The occurrence of Graves' disease and Hashimoto thyroiditis after coronavirus disease 2019 (COVID-19) raised concerns that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may trigger thyroid autoimmunity. We aimed to address the current uncertainties regarding incident thyroid dysfunction and autoimmunity among COVID-19 survivors.

METHODS

We included consecutive adult COVID-19 patients without known thyroid disorders, who were admitted to Queen Mary Hospital from July 21 to September 21, 2020 and had serum levels of thyroid-stimulating hormone, free thyroxine, free triiodothyronine (fT3), and anti-thyroid antibodies measured both on admission and at 3 months.

RESULTS

In total, 122 patients were included. Among 20 patients with abnormal thyroid function tests (TFTs) on admission (mostly low fT3), 15 recovered. Among 102 patients with initial normal TFTs, two had new-onset abnormalities that could represent different phases of thyroiditis. Among 104 patients whose anti-thyroid antibody titers were reassessed, we observed increases in anti-thyroid peroxidase (TPO) (P<0.001) and anti-thyroglobulin (P<0.001), but not anti-thyroid stimulating hormone receptor titers (P=0.486). Of 82 patients with negative anti-TPO findings at baseline, 16 had a significant interval increase in anti-TPO titer by >12 U, and four became anti-TPO-positive. Worse baseline clinical severity (P=0.018), elevated C-reactive protein during hospitalization (P=0.033), and higher baseline anti-TPO titer (P=0.005) were associated with a significant increase in anti-TPO titer.

CONCLUSION

Most patients with thyroid dysfunction on admission recovered during convalescence. Abnormal TFTs suggestive of thyroiditis occurred during convalescence, but infrequently. Importantly, our novel observation of an increase in anti-thyroid antibody titers post-COVID-19 warrants further follow-up for incident thyroid dysfunction among COVID-19 survivors.

Interference of anti-streptavidin antibodies: More common than we thought? In relation to six confirmed cases

Automated immunoassays are extensively used in routine laboratory diagnostics of endocrine disorders because of their advantages, such as high sensitivity, precision, and specificity. However, these methods are limited by the susceptibility of the immunochemical reaction to various interferences. They may present interferences related to the assay's design, for example, the endogenous presence of anti-streptavidin antibodies (ASA) in platforms that use the biotin-streptavidin interaction. To date, there have been few reports in the literature of interference from endogenous ASA. However, such antibodies would potentially lead to falsely decreased or increased results of hormones that can lead to incorrect diagnoses. We report six patients with unusual thyroid function tests, incongruent to their clinical findings. They present elevated concentrations of total T3 and T4 and TSH values within the reference range when measured at Cobas 8000® e801 module (Roche Diagnostics®). Neither patient had been taking biotin; however, all demonstrated the presence of ASA causing falsely high results on competitive assays and also falsely low results on sandwich assays. The hormone panel was also analyzed in the same samples using a different platform available in our laboratory: Cobas 6000® e601 module (Roche Diagnostics®). Nine samples were sent to an external laboratory to be measured with the chemiluminescent method: ADVIA Centaur® (Siemens® Healthcare Diagnostics). The interference seems to affect e801 module and competitive assays the most without affecting results obtained by this chemiluminescent method. This interference could potentially affect other assays performed on the same platform, such as ATPO and estradiol. Finally, laboratories should suspect the presence of interference when there is no correlation between the hormone profile and the patient's clinic. The biotin neutralization protocol demonstrated its effectiveness to eliminate ASA interference.

Impact of dehydroepiandrosterone on thyroid autoimmunity and function in men with autoimmune hypothyroidism

Background Testosterone administration was found to have a protective effect on thyroid autoimmunity in men with autoimmune (Hashimoto's) thyroiditis. Objective The present study was aimed at assessing whether oral dehydroepiandrosterone affects thyroid autoimmunity and hypothalamic-pituitary-thyroid axis activity in men with subclinical hypothyroidism induced by Hashimoto's thyroiditis. Setting The study was conducted at Medical University of Silesia, Katowice, Poland. Method The study enrolled 32 elderly men with autoimmune hypothyroidism and low dehydroepiandrosterone-sulfate levels. Based on patient preference, the participants either received oral dehydroepiandrosterone (50 mg daily; n = 16) or remained untreated (n = 16). Apart from measuring antibody titers and hormone levels, we calculated baseline and post-treatment values of three structure parameters of thyroid homeostasis. Main outcome measure Serum titers of thyroid peroxidase and thyroglobulin antibodies. Results At baseline, there were no significant differences in the investigated parameters between both groups of men. All participants completed the study. Oral dehydroepiandrosterone increased dehydroepiandrosterone-sulfate and testosterone levels, as well as had a neutral effect on estradiol levels. The increase in dehydroepiandrosterone-sulfate correlated with treatment-induced changes in serum testosterone. Moreover, dehydroepiandrosterone reduced titers of thyroid peroxidase and thyroglobulin antibodies, decreased serum thyrotropin levels, reduced Jostel's thyrotropin index as well as increased thyroid's secretory capacity. Treatment-induced changes in thyroid antibody titers, thyrotropin levels, Jostel's thyrotropin index and thyroid's secretory capacity correlated with the increase in dehydroepiandrosterone-sulfate and testosterone levels. Conclusion The obtained results show that exogenous dehydroepiandrosterone may exert a beneficial effect on thyroid autoimmunity and hypothalamic-pituitary-thyroid axis activity in men with autoimmune thyroiditis and subclinical hypothyroidism.

Insulin resistance and pancreatic β cell dysfunction are associated with thyroid hormone functions: A cross-sectional hospital-based study in Turkey

BACKGROUND AND AIMS

The prevalence of thyroid disease in diabetic patients is significantly higher than the general population. This indicates a possible interaction between thyroid functions and insulin sensitivity. This study aimed to investigate the relationship between insulin resistance (IR), pancreatic β cell function, and thyroid function tests.

METHODS

This cross-sectional study was conducted with adults who applied to Eskişehir Osmangazi University Hospital for general control. Fasting insulin, glucose, TSH, fT3, and fT4 levels in the serum of 1340 adult (18-60 aged) patients without any chronic diseases were examined retrospectively. The fT3/fT4 ratio, Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), and HOMA-β values were calculated. The correlation between HOMA-IR and HOMA-β values with thyroid function tests and differences between hormone levels of patients with and without IR were evaluated.

RESULTS

There was a positive correlation between HOMA-IR and TSH, negative with fT4. Also, a positive correlation between HOMA-β and fT3, negative correlation with fT4 were observed. In the IR group, fT3 levels were found significantly higher and fT4 levels were significantly lower. TSH levels were higher in the IR group but not statistically significant. The fT3/fT4 ratio was found significantly higher in the IR group and was correlated positively with both HOMA-IR and HOMA-β.

CONCLUSION

Our results revealed that thyroid dysfunction prevalence is quite high in adults who have not yet been diagnosed with diabetes but have insulin resistance and the onset of pancreatic β cell dysfunction.

Total T4 rise in pregnancy: a relook?

Background

Total T4 (TT4) measurement is preferred to free T4 (FT4) especially in last part of pregnancy. Guidelines by American Thyroid Association, European Thyroid Association and Endocrine Society state that TT4 increases 1.5 times pre-pregnant levels after week 16 of pregnancy. However, this is based on a small study conducted 40 years ago which used radioimmunoassay for determination in changes in TT4.

Materials and methods

A cross-sectional study was undertaken to find reference interval for thyroid function in different trimester of pregnancy with special reference to look at the degree of elevation of TT4 as compared to non-pregnant women. Two hundred non-pregnant women (excluding oral contraceptive users) and 600 pregnant women (200 from each trimester) aged 18–40 years were consecutively recruited starting from around 6th week of pregnancy having confirmed singleton pregnancy diagnosed at 8th week by ultrasound. The exclusion criteria included: (1) a personal or family history of thyroid disease; (2) presence of goiter or nodule confirmed by ultrasound; (3) anti-TPO antibody positive state (titre > 35 IU/ml). All subjects were tested for urinary spot iodine concentration and those with UIC < 150 μg/L were excluded. Finally, thyroid function tests (TSH, FT4, TT4, TT3) of 168 non-pregnant women and 163, 153 and 148 women at 1st, 2nd and 3rd trimester respectively were analysed..

Results

Total T4 (mean ± SD, μg/dl) in non pregnant women and in different trimesters was 8.95 ± 1.71, 9.71 ± 2.39, 12.11 ± 1.55, 11.83 ± 1.49 respectively. Rise in TT4 occurred between 10-18th week. The mean TT4 in second trimester increased by 25% as compared with the value at 6-9th week and by 35% as compared to non-pregnant value.

Conclusion

Rise in total T4 in second trimester pregnancy is only around 25% as compared to first trimester value and 35% than the non-pregnant value. Hence multiplying non-pregnant T4 value by 1.5 may actually over-diagnose maternal hypothroxinemia and lead to inappropriate diagnosis and treatment of isolated maternal hypothyroxinemia in a significant proportion of subjects.

Thyroid Function in Children with Down Syndrome in the Polish Population: A Case-Control Study

BACKGROUND

Patients with subclinical thyroid disease have few or no clinical symptoms of thyroid dysfunction and thus, laboratory diagnosis is needed. In this context, the objective of the current study was to analyze the prevalence rate and pattern of thyroid function in children with Down syndrome in the Polish population.

METHODS

A total of 30 children, aged 6-12 years, with cytogenetically confirmed Down syndrome were studied. The control group included 27 children.

RESULTS

Of the 30 patients with Down syndrome, 14 (46.7%) had abnormal thyroid profiles. Mean thyroid-stimulating hormone (TSH) and fT4 concentrations in children with Down syndrome were found to be significantly increased compared with the controls (4.30 ± 1.9 µIU/mL, 95% CI: 3.55-5.04 µIU/mL vs. 3.10 ± 1.47 µIU/mL, 95% CI: 2.52-3.68 µIU/mL, P = 0.013, 95% CI: 0.26-2.14, and 1.33 ± 0.23 ng/dL, 95% CI: 1.25-1.42 vs. 1.19 ± 0.14 ng/dL, 95% CI: 1.13-1.25, P = 0.008, 95% CI: 0.04-0.24, respectively). In Down syndrome, subclinical hypothyroidism was recognized in 10 children (33.3%) (high TSH and normal fT4 and fT3 levels). Two children (6.67%) had evident hypothyroidism (high TSH and low fT4). In the control group, subclinical hypothyroidism was diagnosed in four (14.8%) children.

CONCLUSION

Children with Down syndrome may have increased secretion of TSH, even when thyroid hormone and autoantibodies are normal, suggesting that an isolated increase in TSH does not predispose the patient to the development of thyroid disease. We also recommend that all patients with Down syndrome should be screened for thyroid dysgenesis, since they have thyroid dysfunction more frequently as compared to the general healthy population.

Thyroid isthmus agenesis and its clinical significance in a large-scale multidetector CT-based study

OBJECTIVE

The purpose of this study was to estimate the incidence and clinical significance of thyroid isthmus agenesis based on multi-detector CT imaging in a large-scale study.

METHODS

Data from 1601 patients who underwent neck multi-detector CT at our institution from January 2015 to March 2016 were included in this retrospective study. The morphology of each patient's thyroid gland was evaluated. We classified thyroid isthmus agenesis into two subgroups according to the thickness of the medial margin: clear-cut type (>4 mm) or tapering-edge type (≤4 mm). Associated thyroid pathologies were also evaluated.

RESULTS

Thyroid isthmus agenesis was present in 69 patients (41 males, 28 females), and its incidence was 4.77%. Eleven patients (0.76%) had the clear-cut type and 58 patients (4.01%) had the tapering-edge type. Papillary thyroid carcinoma was diagnosed in 4 patients (5.7% of isthmus agenesis patients). A total of 7 patients underwent thyroid function testing during the course of this study; 1 of these patients presented with borderline hyperthyroidism, and the remaining 6 were in a euthyroid state. The clear-cut type showed a statistically significant narrow gap and a high incidence of pyramidal lobes compared to the tapering-edge type.

CONCLUSION

Thyroid isthmus agenesis is not a rare developmental anomaly of the thyroid gland on multi-detector CT. Based on the metastatic pathophysiology of differentiated thyroid cancer, more extended indications for lobectomy are expected in differentiated thyroid cancer patients with thyroid isthmus agenesis.

Exploring the role of copper and selenium in the maintenance of normal thyroid function among healthy Koreans

BACKGROUND

Selenium and iodine are trace elements well known to have important roles in the synthesis and metabolism of thyroid hormones. However, the effects of other trace elements on thyroid hormones are still inconclusive. We investigated the association between several trace elements and thyroid hormones.

METHODS

The data of 448 subjects who were measured for both, trace elements and TSH/free T4, at the Heath Checkup Center were retrospectively reviewed. The presence of thyroiditis (from thyroid echogenicity) and thyroid nodules were reviewed in the subjects who underwent thyroid ultrasonography.

RESULTS

Blood concentrations of manganese, copper, selenium, and molybdenum were associated with TSH or free T4. After adjusting for age, sex, BMI, smoking, and alcohol consumption, blood copper levels were positively associated with free T4 in both sexes and selenium levels were positively associated with free T4 in women. There was no association between trace elements and thyroiditis. Blood copper concentration had a weak non-linear association with the presence of thyroid nodules.

CONCLUSIONS

This study demonstrated that blood concentrations of copper and selenium were significantly associated with free T4 in healthy Korean subjects with sufficient iodine intake suggesting their role in maintaining normal thyroid function.

A practical approach towards the evaluation of aberrant thyroid function tests

Objective: To provide insight in patterns and causes of aberrant thyroid function tests (TFT) and to propose a practical approach for clinicians.Methods: Starting from an illustrative case report, an extensive literature search was performed, resulting in a narrative literature review.Results: TFT that cannot be explained by the negative feedback principle of the hypothalamo-pituitary-thyroid axis are a challenge for every clinician. Various alternative explanations for these TFT should be considered before drawing the conclusion of thyroid disorder, since incorrect diagnosis and treatment can have severe consequences for the patient.For example, the combination of elevated or normal TSH with elevated free T4 or T3 levels may result from the use of certain drugs or lab interference, while low or normal TSH with low T3 or T4 can often be explained by non-thyroidal illness or central hypothyroidism due to pituitary failure. Correct identification of these clinical situations requires understanding thyroid hormone metabolism and action, knowledge of some laboratory techniques, and a multistep evaluation process.Conclusion: To avoid incorrect diagnosis and thus treatment, clinicians should be aware of the existence of aberrant TFT and know how to decipher them.

Association between Serum Free Thyroxine and Anemia in Euthyroid Adults: A Nationwide Study

BACKGROUND

Studies on the relationship between thyroid function and anemia in the euthyroid range are scarce. We aimed to evaluate the association between anemia and serum free thyroxine (fT4) and thyrotropin (TSH) in euthyroid adults.

METHODS

Data on 5,352 participants aged ≥19 years were obtained from the Korea National Health and Nutrition Examination Survey VI (2013 to 2015). Anemia was defined as hemoglobin (Hb) <13 and <12 g/dL for men and women, respectively.

RESULTS

Overall, 6.1% of participants had anemia, and more women (9.9%) had anemia than men (2.8%, P<0.001). In multivariate analysis, serum fT4 levels, but not TSH, were positively associated with serum Hb levels in both sexes (P<0.001, each). Serum Hb levels linearly reduced across decreasing serum fT4 quartile groups in both sexes (P<0.001, each). After adjusting for potential confounding factors, participants with low-normal fT4 had 4.4 (P=0.003) and 2.8 times (P<0.001) higher risk for anemia than those with high-normal fT4 among men and women, respectively. When participants were divided into two groups at 50 years of age, in younger participants, men and women with the first quartile were at higher risk of anemia than men with the second quartile (odds ratio [OR], 3.3; P=0.029) and women with the forth quartile (OR, 3.2; P<0.001), respectively. This association was not observed in older participants.

CONCLUSION

These results suggest that a low-normal level of serum fT4 was associated with a lower serum Hb level and a higher risk of anemia in euthyroid adults, especially in younger participants.

Are thyroid function tests in neonates born to mothers with hypothyroidism clinically useful?

Thyroid function tests from all babies born to mothers with hypothyroidism (381 neonates) during a 6-year period, were collected and examined against findings of the universal screening test. No difference was found between the results of bloodspot test and later blood test. Additional blood tests for thyroid function in this population of neonates seem to be without clinical value and may be discontinued.

Risk factors for hypothyroidism in euthyroid thyroid nodule patients with lymphocytic thyroiditis on fine needle aspiration cytology

BACKGROUND/AIMS

Lymphocytic thyroiditis as cytology diagnosis from fine needle aspiration (FNA) is frequently detected in patients with thyroid nodules. However, the clinical outcome for upcoming hypothyroid events has been rarely clarified in euthyroid patients.

METHODS

We retrospectively reviewed the data of patient who had lymphocytic thyroitidis on FNA cytology of thyroid nodule from January 2005 to December 2010 at a tertiary referral hospital. In total, 109 patients with follow-up thyroid function tests (TFT) were enrolled. Final outcomes included overt and subclinical hypothyroidism with thyroid stimulating hormone (TSH) levels ≥ 10 mIU/L. Potential parameters predicting clinical hypothyroidism were analyzed by multivariate analysis.

RESULTS

Over the mean follow-up duration of 51.6 months, 14 out of 109 patients (12.8%) developed clinical hypothyroidism that required thyroid hormone replacement. The median onset time to hypothyroidism was 16 months (range, 3 to 88) and ≥ 60% of patients experienced clinical hypothyroidism within 1 year. By multivariate analysis, background thyroiditis (relative risk [RR], 9.78; p = 0.004), thyroid peroxidase antibody positivity (RR, 9.90; p = 0.003), nodule size (RR, 1.24; p < 0.001), and initial TSH (RR, 1.47; p = 0.009) were the independent risk factors for predicting hypothyroidism in euthyroid patients.

CONCLUSION

Hypothyroidism frequently occurs during the follow-up in euthyroid patients with thyroid nodules which show lymphocytic thyroiditis on FNA cytology. Close surveillance and regular TFT are needed in high-risk patients for upcoming clinical hypothyroidism.

Initial and delayed thyroid-stimulating hormone elevation in extremely low-birth-weight infants

BACKGROUND

To determine the incidence, etiology, and outcomes of thyroid-stimulating hormone (TSH) elevation in extremely low-birth-weight infants (ELBWIs).

METHODS

Newborn thyroid screening data of 584 ELBWIs (birth weight, < 1000 g; gestational age, ≥ 23 weeks) were retrospectively analyzed to identify initial (≤ 2 postnatal weeks) and delayed (> 2 weeks) TSH elevations. Growth and neurodevelopmental outcomes at 2 years' corrected age (CA) were assessed according to levothyroxine replacement.

RESULTS

Initial and delayed TSH elevations were detected at CAs of 27 and 30 weeks, respectively, with incidence rates of 0.9 and 7.2%, respectively. All infants with initial TSH elevations had perinatal asphyxia, and 95% of those with delayed TSH elevation were exposed to various stressors, including respiratory support, drugs, and surgery within 2 weeks before diagnosis of TSH elevation. Free thyroxine (T4) levels were simultaneously reduced in 80 and 57% of infants with initial and delayed TSH elevations, respectively. Both initial and delayed TSH elevations were transient, regardless of levothyroxine replacement. Infants receiving levothyroxine replacement therapy had significantly higher TSH elevations, significantly lower free T4 levels, and significantly reduced mortality, compared to untreated infants. However, levothyroxine replacement had no significant effect on long-term growth and neurodevelopmental outcomes.

CONCLUSIONS

The timing of insult superimposition on hypothalamic-pituitary-thyroid axis maturation is a major determinant of initial or delayed TSH elevation in ELBWIs. Levothyroxine replacement did not affect growth or neurodevelopmental outcomes in this population.

The effect of vitamin D on thyroid autoimmunity in euthyroid men with autoimmune thyroiditis and testosterone deficiency

BACKGROUND

Autoimmune (Hashimoto's thyroiditis) is characterized by a strong female preponderance, which may suggest that sex hormones have an impact on thyroid autoimmunity. The aim of this study was to investigate whether testosterone determines vitamin D action on thyroid antibody titers and thyroid function tests in men with autoimmune thyroiditis and low testosterone levels.

METHODS

The study included 36 men with testosterone deficiency, 17 of whom had been treated for at least 26 weeks with oral testosterone undecanoate (120 mg daily). Because of coexistent euthyroid Hashimoto's thyroiditis, all participants were then treated with vitamin D (100 μg daily). Serum titers of thyroid peroxidase and thyroglobulin antibodies, serum levels of thyrotropin, free thyroid hormones, testosterone and 25-hydroxyvitamin D, as well as Jostel's thyrotropin index, SPINA-GT and SPINA-GD were assessed before vitamin D treatment and 26 weeks later.

RESULTS

With the exception of testosterone levels, there were no significant differences between both study groups in serum hormone levels, antibody titers and thyroid function tests. All participants completed the study. In addition to increasing 25-hydroxyvitamin D levels, vitamin D increased SPINA-GT and reduced thyroid peroxidase and thyroglobulin antibody titers. In testosterone-treated men, vitamin D increased testosterone levels. Vitamin D did not affect serum levels of thyrotropin, free thyroid hormones, Jostel's thyrotropin index and SPINA-GD. Treatment-induced changes in thyroid antibody titers and SPINA-GT were more pronounced in testosterone-treated than testosterone-naïve men.

CONCLUSIONS

The obtained results suggest that the beneficial effect on thyroid autoimmunity and thyroid secretory function is stronger in men receiving testosterone therapy.

[Thyroid medicine for ENT physicians]

Diseases of the thyroid gland are frequent incidental findings during ultrasound examination of the neck. They affect nearly one third of the normal population. Treatment is not always indicated; however, laboratory diagnostic measures must be initiated to specify the disease. The primary indications for consulting a thyroid specialist are thyroid nodules, goiters, autonomy of the thyroid gland, autoimmune diseases, Graves' disease, and Hashimoto thyroiditis. The aim of this review is to provide an overview of the most important thyroid diseases and their treatment options.

Variation of iodine status during pregnancy and its associations with thyroid function in women from Rio de Janeiro, Brazil

OBJECTIVE

To assess iodine status and its effects on maternal thyroid function throughout pregnancy.

DESIGN

In the present prospective cohort study, three urinary samples were requested for urinary iodine concentration (UIC) determinations in both the first and third gestational trimesters. Serum thyrotropin (TSH) and free thyroxine (FT4) were analysed in both trimesters and thyroid antibodies were assessed once.

SETTING

Rio de Janeiro, Brazil.ParticipantsFirst-trimester pregnant women (n 243), of whom 100 were re-evaluated during the third trimester.

RESULTS

Iodine sufficiency was found in the studied population (median UIC=216·7 µg/l). The first- and third-trimester median UIC was 221·0 and 208·0 µg/l, respectively. TSH levels (mean (sd)) were higher in the third trimester (1·08 (0·67) v. 1·67 (0·86) mIU/l; P&lt;0·001), while FT4 levels decreased significantly (1·18 (0·16) v. 0·88 (0·12) ng/dl; P&lt;0·001), regardless the presence of iodine deficiency (UIC&lt;150 µg/l) or circulating thyroid antibodies. UIC correlated (β; 95% CI) independently and negatively with age (-0·43; -0·71, -0·17) and positively with multiparity (0·15; 0·02, 0·28) and BMI (0·25; 0·00, 0·50). Furthermore, median UIC per pregnant woman tended to correlate positively with TSH (0·07; -0·01, 0·14). Women with median UIC≥250 µg/l and at least one sample ≥500 µg/l throughout pregnancy had a higher risk of subclinical hypothyroidism (OR=6·6; 95% CI 1·2, 37·4).

CONCLUSIONS

In this cohort with adequate iodine status during pregnancy, excessive UIC was associated with an increased risk of subclinical hypothyroidism.

The effect of vitamin D and selenomethionine on thyroid antibody titers, hypothalamic-pituitary-thyroid axis activity and thyroid function tests in men with Hashimoto's thyroiditis: A pilot study

BACKGROUND

Both selenium and vitamin D were found to reduce thyroid antibody titers in women with Hashimoto's thyroiditis.

METHODS

The study enrolled 37 young drug-naïve euthyroid men with autoimmune thyroiditis, who were treated for 6 months with either exogenous vitamin D (group A, n = 20) or selenomethionine (group B, n = 17). Serum titers of thyroid peroxidase and thyroglobulin antibodies, serum levels of thyrotropin and free thyroid hormones, serum levels of 25-hydroxyvitamin D, as well Jostel's thyrotropin, the SPINA-GT and the SPINA-GD indices were determined at the beginning and at the end of the study.

RESULTS

At baseline, there were no differences between the study groups. Both vitamin D and selenomethionine reduced antibody titers and increased the SPINA-GT index. Only selenomethionine affected the SPINA-GD index, while only vitamin D increased 25-hydroxyvitamin D levels. Neither selenomethionine nor vitamin D significantly affected thyrotropin and free thyroid hormone levels. The effect of vitamin D on antibody titers correlated with baseline and treatment-induced changes in serum levels of 25-hydroxivitamin D.

CONCLUSIONS

Both vitamin D and selenomethionine have a beneficial effect on thyroid autoimmunity in drug-naïve men with Hashimoto's thyroiditis.

Implementation of thyroid function tests algorithms by clinical laboratories: A four-year experience of good clinical and diagnostic practice in a tertiary hospital in Greece

INTRODUCTION

Thyroid Function Tests (TFTs) are among the most commontly ordered tests. Significant overuse of TFTs can occur when instead of using a single TSH test to screen for thyroid disease a full panel (TSH plus FT4 and FT3) is ordered. The aim of our study was to evaluate the effectiveness of the application of a scientifically-established laboratory-controlled algorithm for TFTs to physician's orders for inpatients and to address potential pitfalls of such an approach.

MATERIALS AND METHODS

We collected and analyzed Laboratory Information System data of the TFTs performed between April 2009 and March 2016 in a 739-bed tertiary teaching hospital. Between April 2013 and March 2016, we applied a laboratory controlled algorithm for inpatient TFT assays after TSH and did not perform further tests, unless a justified bypass was requested by the treating physician.

RESULTS

Algorithm application led to significant reductions of TFTs executed per TSH ordered. Compared to the four years preceding the intervention, executed FT4/TSH tests decreased from 93 to 18%, FT3/TSH from 92 to 18%, anti-TG/TSH from 18 to 4% and anti-TPO/TSH from 11 to 3%. Simultaneously, FT4, FT3, anti-TG, and anti-TPO tests ordered in outpatients also displayed a significant gradual decrease.

CONCLUSIONS

Hospital-based laboratories can safely apply a generally accepted TFTs algorithm on physician's orders without any compromise in diagnostic/therapeutic accuracy, thus achieving significant direct cost-reduction and increased physician awareness on current TFT ordering practices. Such an approach, combined with collaboration with ordering physicians, can safeguard patients from the consequences of low-value care practices.

Prognostic value of cortisol and thyroid function tests in poisoned patients admitted to toxicology ICU

BACKGROUND

Prognostic value of cortisol and thyroid function tests (TFTs) has previously been evaluated in medical ICUs. We aimed to evaluate prognostic efficacy of cortisol and TFTs in critically ill poisoned patients admitted to toxicology intensive care unit (ICU).

METHODS

In a prospective study of consecutively enrolled subjects admitted to the toxicology ICU, lab analyses included TFTs (total T3 and T4 as well as TSH) and cortisol levels drawn between 8 am-10 am during period of the first 24 hours post-ingestion/exposure. Simplified Acute Physiology Score II (SAPS II) and Acute Physiology and Chronic Health Evaluation II (APACHE II) were recorded. All scores were compared to detect the best prognostic factor. Type of poisoning was also included.

RESULTS

In 200 patients evaluated, 129 were male and mean age was 31 years. In general, SAPS II, T4, and cortisol could prognosticate death. After regression analysis, only cortisol had such efficacy (P=0.04; OR=1.06; 95%CI=1.05-1.08; cut-off=42 µg/dL; sensitivity=70%; specificity=82%). Between aluminium phosphide (ALP)- and non ALP-poisoned patients, level of consciousness, mean arterial pressure, and cortisol level could prognosticate death in ALP poisoning (all Ps<0.001 in both uni and multivariate analyses). Median (interquartile range; IQR) GCS was 7 (6, 10) and 15 (8, 15) in non-ALP and ALP-poisoned patients (P<0.003). SAPS II and APACHE II could not prognosticate death at all.

CONCLUSION

Cortisol best prognosticated outcomes for subjects admitted to the toxicology ICU. Its level is higher in ALP-poisoned patients probably due to the higher stress while they remain conscious till the final stages of toxicity and are aware of deterioration of their clinical condition or may be due to their significantly lower blood pressures.

"Hypothyroidism screening during first trimester of pregnancy"

Background

Subclinical hypothyroidism is defined as an elevated thyroid-stimulating hormone level with a normal thyroxin level without signs or symptoms of hypothyroidism. Although it is well accepted that overt hypothyroidism has a deleterious impact on pregnancy, recent studies indicate that subclinical hypothyroidism may affect maternal and fetal health. Studies suggest an association between miscarriage and preterm delivery in euthyroid women positive for anti-peroxidase antibodies and/or anti-thyroglobulin antibodies. A proposal of a new set-point to diagnose SCH was recently published. The aim of this research was to determine the optimal thyroid-stimulating hormone cut-off point to screen for subclinical hypothyroidism in the first trimester of gestation in a population of our clinical area and to determine the diagnostic value of this screening test for detecting anti-thyroid peroxidase antibodies.

Methods

This cross-sectional study determines the cutoff point for SCH screening and evaluates its usefulness to detect TPO Ab using the Receiver Operating Characteristics (ROC) curve. Prevalence of SCH was calculated using as cut-off 2.5 mIU/L, 4 mIU/L, and our TSH 97.5th percentile. The ability to detect positive anti-thyroglobulin antibodies (TG Ab) and anti-thyroid peroxidase antibodies (TPO Ab) in patients with levels of TSH >97.5th percentile was determined by ROC curves.

Results

The mean, range and standard deviation of TSH was 2.15 ± 1.34 mIU/L (range 0.03–8.82); FT4 was 1.18 ± 0.13 ng/dL (range 0.94–1.3); TG Ab was 89.87 ± 413.56 IU/mL (range 0.10–4000); and TPO Ab was 21.61 ± 46.27 IU/mL(range 0.10–412.4). The ROC. analysis of the ability of the TSH level to predict the presence of positive TPO Ab found an AUC of 0.563.

Conclusion

In our population, the TSH cutoff value for gestational SCH screening is 4.7 mIU/L. Using the SEGO recommended 2.5 mIU/L TSH cut-off point, the prevalence of SCH is 37%. Applying the ATA 2017 recommended cutoff point of 4 mIU/L, the prevalence of SCH is 9.6%. Finally, when the cut-off of 4.7 mIU/L (our 97.5th centile) was used, the SCH prevalence is 5%. TSH levels in the first trimester of pregnancy are not useful to detect TPO Ab.

Clinical course of infants with congenital heart disease who developed thyroid dysfunction within 100 days

PURPOSE

We investigated the clinical course of infants with congenital heart disease (CHD) who experienced thyroid dysfunction within 100 days of birth.

METHODS

We performed retrospective medical reviews of 54 CHD patients (24 male patients) who underwent a thyroid function test (TFT) between January 2007 and July 2016. Data were collected on birth history, diagnosis of CHD, underlying chromosomal or genetic abnormalities, medication history, surgery, ventilator care, and exposure to iodine contrast media (ICM). Results of neonatal screening tests (NSTs) and TFTs were reviewed.

RESULTS

A total of 36 patients (29 transient, 7 permanent) showed thyroid dysfunction. Among the seven patients with permanent hypothyroidism, three had an underlying syndrome, three showed abnormal NST results, and one was admitted to the intensive care unit for macroglossia and feeding cyanosis. We found that infants with transient thyroid dysfunction had a lower birth weight and were more commonly exposed to thyroid disrupting medication and/or ICM. However, these risk factors were not significant. A total of 8 patients with a history of ICM exposure showed thyroid dysfunction. Excluding 3 patients with elevated thyroid stimulating hormone before ICM exposure, 5 patients recovered from transient thyroid dysfunction.

CONCLUSIONS

We observed thyroid dysfunction in two-thirds of CHD infants (53.7% transient, 13.0% permanent) who had risk factors and received TFT screening within 100 days, despite normal NSTs. Further studies with larger sample sizes are required to revise the criteria for TFT screening in CHD infants.

Hypothyroidism in hospitalized elderly patients: a sign of worse prognosis

PURPOSE

Overt hypothyroidism has adverse clinical consequences and might worsen prognosis in critically ill elderly patients. However, the difficult interpretation of thyroid function tests (TFT) due to non-thyroidal illness (NTI) has led to discouragement of screening for thyroid dysfunction. Our aim was to determine the prevalence of TFT compatible with hypothyroidism and to study its influence on mortality among hospitalized elderly patients.

METHODS

In this prospective study we consecutively included all patients ≥60 years admitted by the Internal Medicine Department to the hospital ward (n = 451) of the Cesar Milstein Hospital in Buenos Aires, Argentina. TFT were done on day 1 and 8. Thyroid function categories were defined as overt and subclinical hypothyroidism, overt and subclinical hyperthyroidism, euthyroidism and NTI. Stage of chronic kidney disease (CKD), Adult Comorbidity Evaluation (ACE)-27, and intra-hospital mortality were recorded. The association between mortality and TFT categories was studied by Cox regression.

RESULTS

Out of 451 patients (77.0 ± 7.9 years, 54% females) 76% were categorized as NTI, 4% as overt hypothyroid, 10% as subclinical hypothyroid, 1% as subclinical hyperthyroid and 9% as euthyroid. Overt hypothyroid patients showed significantly higher mortality than the rest of the groups (25%, p < 0.05) while ACE-27 was similar among all of them (p = 0.658). In addition, patients within the overt hypothyroid category showed a higher mortality rate than NTI in a model adjusted by Stage 5-CKD, ACE-27, sex and age [HR 3.1 (1.14-8.41), p < 0.026].

CONCLUSION

Overt hypothyroidism during hospitalization was associated with elevated mortality. Further studies would reveal if TFT alterations compatible with hypothyroidism should be diagnosed/treated in hospitalized elderly patients.

Age-specific reference interval of serum TSH levels is high in adolescence in an iodine excess area: Korea national health and nutrition examination survey data

PURPOSE

Serum thyroid-stimulating hormone level was influenced by several factors, including age, gender, thyroid auto-antibodies, race, and intake of dietary iodine. We evaluated age-specific reference interval of serum thyroid-stimulating hormone levels in Korea, an iodine excess area.

METHODS

This nationwide population-based cross-sectional study included representative civilian, non-institutional population (n = 6564) who underwent thyroid function tests from Korea National Health and Nutrition Examination Survey VI (2013-2015). The reference interval of serum thyroid-stimulating hormone levels was defined between the 2.5th and 97.5th percentiles in the reference population.

RESULTS

The geometric mean of serum thyroid-stimulating hormone levels in the reference population was 2.17 mIU/L with a reference interval of 0.62-6.84 mIU/L. In the reference population, the geometric mean of serum TSH levels in each age group of 10-18, 19-29, 30-39, 40-49, 50-59, 60-69, and equal or older than 70 years was 2.47, 2.20, 2.07, 2.04, 2.23, 2.12, and 2.27 mIU/L, with a reference interval of 0.74-7.35, 0.67-6.42, 0.63-6.04, 0.62-6.20, 0.56-7.37, 0.57-6.90, and 0.42-6.58 mIU/L, respectively. In the reference population, the urinary iodine concentrations were consistently high in all age groups (median 298.5 μg/L). Subjects aged 10-18 years had the highest urinary iodine concentrations.

CONCLUSIONS

There was no shift toward higher levels with age in the distribution of serum thyroid-stimulating hormone levels. The reference interval of serum thyroid-stimulating hormone levels was consistently high in all age group, especially from adolescence 10-18 years in a Korean population who had excessive intake of dietary iodine.

Ischemic Stroke and Impact of Thyroid Profile at Presentation: A Systematic Review and Meta-analysis of Observational Studies. J Stroke Cerebrovasc Dis. 2017;26:2926-2934. [PMID: 28821377 DOI: 10.1016/j.jstrokecerebrovasdis.2017.07.015]

BACKGROUND

Stroke is the fifth leading cause of mortality in the United States and a leading cause of disability. A complex relationship between thyroid hormone levels and severity of, and outcome after, stroke has been described.

AIM

Our objective is to identify the association between baseline thyroid function profile and outcome after acute ischemic stroke.

METHODS

Studies looking at the association between thyroid function and functional stroke outcomes were identified from available electronic databases from inception to December 16, 2016. Study-specific risk ratios were extracted and combined with a random effects model meta-analysis.

RESULTS

In the analysis of 12 studies with 5218 patients, we found that subclinical hypothyroidism was associated with better modified Rankin scale scores at 1 and 3 months (odds ratio [OR] 2.58, 95% confidence interval [CI] 1.13-5.91, P = .03 and OR 2.28, 95% CI 1.13-3.91, P = .003, respectively) compared with the euthyroid cases. Likewise, patients with higher initial thyrotropin-releasing hormone (TSH) and fT3 or T3 levels had favorable outcomes at discharge (mean differences of TSH .12 [95% CI .03-.22, P = .009] and of fT3 .36 (CI .20-.53, P < .0001]) and at 3 months (mean differences of TSH .25 [95% CI .03-.47, P = .03] and of T3 8.60 [CI 4.58-12.61, P < .0001]).

CONCLUSIONS

Elevated initial TSH (clinical or subclinical hypothyroidism) may correspond to better functional outcomes, whereas low initial T3/fT3 might correlate with worse outcomes in acute ischemic stroke among clinically euthyroid patients. This complex relation merits further well-designed investigations. Whether correcting thyroid profile with hormone supplementation or antagonism may lead to improved outcomes will require large, prospective, interventional studies.

Effects of Levothyroxine Administration and Withdrawal on the Hypothalamic-Pituitary-Thyroid Axis in Euthyroid Dogs

Background

Chronic supplementation can suppress the hypothalamic‐pituitary‐thyroid axis (HPTA) and make it difficult to assess thyroid function after withdrawal of levothyroxine.

Objectives

To determine whether the HPTA is suppressed after levothyroxine administration in euthyroid dogs and the time required for resolution of any suppression.

Animals

Twenty‐eight healthy euthyroid dogs.

Methods

A prospective, randomized study administering levothyroxine to euthyroid dogs for 8 weeks (group 1) or 16 weeks (group 2). Serum concentrations of total thyroxine (T₄), free thyroxine (fT₄) by equilibrium dialysis, thyroid stimulating hormone; thyrotropin (TSH), and 3,5,3′‐triiodothyronine (T₃) were measured every 4 weeks during supplementation and for 16 weeks after levothyroxine was discontinued.

Results

Mean serum concentrations of T₄ and fT₄ were significantly higher (P < .0001) and TSH was lower (P < .0001) in all dogs during levothyroxine administration compared to baseline. Mean serum concentrations of T₄, fT_4, and TSH in both groups, beginning 1 week after levothyroxine was discontinued, were significantly different (P < .01) compared to values during levothyroxine administration but not compared to baseline values (P > .3).

Conclusions and Clinical Importance

Assessing thyroid function tests 1 week after cessation of levothyroxine at 26 μg/kg once a day for up to 16 weeks will provide an accurate assessment of thyroid function in healthy euthyroid dogs.

Liver cirrhosis and thyroid function: Friend or foe?

INTRODUCTION

The liver plays a central role in thyroid hormone metabolism, transport, and clearance. A normal function of both the thyroid gland and the liver is therefore necessary to maintain normal thyroid hormone levels and action. Data regarding thyroid function in patients with liver cirrhosis are scarce and variable. The most consistent finding is a decreased free triiodothyronine (fT3) level, which correlates with the severity of liver disease and has been proposed as a prognostic factor for liver-related complications.

AIM OF THE STUDY

To evaluate thyroid hormone values in patients with stable liver cirrhosis and to compare them with healthy controls without liver disease. We also assessed the prevalence of thyroid autoimmunity and whether liver function tests correlated with thyroid function.

MATERIAL AND METHODS

We performed a prospective case-control study in an endocrinological setting. Twenty-nine patients with stable cirrhosis (20 males and 9 females, mean age 60.97 ± 7.17 years) were included in the case group and 50 healthy subjects (22 males and 28 females, mean age 61.70 ± 13.00 years) in the control group. We excluded patients with confounding factors known to influence thyroid function. Levels of serum thyroid-stimulating hormone (TSH), fT3, free thyroxine (fT4) and anti-TPO-antibodies (TPO-Ab) were measured. These thyroid hormone values were compared in both groups. Biochemical indices of liver function (aspartate aminotransferase [AST], alanine aminotransferase [ALT], alkaline phosphatase [AP], gamma-glutamyl transpeptidase [GGT], INR, total bilirubin, and albumin levels) were correlated with thyroid function tests.

RESULTS

fT3 en fT4 levels were significantly lower in patients with cirrhosis than in healthy subjects (p = 0.001 and 0.002, respectively). TSH levels were not statistically significantly different in the two groups. The level of TPO-Ab was not increased in patients with cirrhosis compared to healthy controls. fT3 correlated negatively with the Child-Pugh score.

DISCUSSION

These results indicate that, compared to healthy controls, patients with cirrhosis have decreased fT3 and fT4 levels and comparable TSH levels and may be consistent with findings of limited acquired central hypothyroidism as observed in the non-thyroidal illness syndrome (NTIS). fT3 levels correlated negatively with Child-Pugh score, a measure of severity of liver dysfunction. We did not find an increased prevalence of thyroid autoimmunity in these patients.

Thyroid function testing in neonates born to women with hypothyroidism

Our aim was to assess the utility of serum thyroxine and thyroid stimulating hormone performed at 10-14 days of life in diagnosing congenital hypothyroidism (CH) in babies born to mothers with hypothyroidism. This was a retrospective study of all babies born in a tertiary referral centre for neonatology over a 12-month period. Infants who had thyroid function testing (TFT) checked at 10-14 days of life because of maternal hypothyroidism during the period of study were included. The results of the newborn bloodspot and day 10-14 TFT were recorded along with whether or not patients were subsequently treated. Of the 319 patients included in the study, only two patients were found to have CH and in both cases the newborn blood spot had been abnormal.

CONCLUSION

No extra cases of CH were detected from the thyroid test at 10-14 days and this practice should be discontinued due to the robust nature of existing newborn screening programmes. What is Known: • Congenital hypothyroidism(CH) is the commonest preventable cause of childhood intellectual impairment. • Family history of hypothyroidism has been implicated as a risk factor for CH. • CH has formed part of newborn screening since the 1970s. What is New: • There is no research recommending thyroid function testing at 10-14 days of life to detect CH in neonates born to mothers with hypothyroidism. • Thyroid function testing at 10-14 days of life does not improve diagnostic yield for CH in babies born to mothers with hypothyroidism. • Newborn blood spot remains the mainstay for accurate and timely diagnosis of CH.

Short-term amiodarone treatment for atrial fibrillation after catheter ablation induces a transient thyroid dysfunction: Results from the placebo-controlled, randomized AMIO-CAT trial

BACKGROUND

Amiodarone is known to affect the thyroid, but little is known about thyroid recovery after short-term amiodarone treatment.

OBJECTIVES

We aimed to evaluate the impact of 8weeks of amiodarone treatment on thyroid function in patients with atrial fibrillation (AF) undergoing catheter ablation in a randomised, double-blind clinical trial.

METHODS

212 patients referred for AF ablation at two centres were randomized to 8weeks of oral amiodarone or placebo. Thyroid function tests (TSH, thyroid stimulating hormone; T4, thyroxine; T3, triiodothyronine; fT4, free T4; fT3, free T3) were performed at baseline and 1, 3 and 6months.

RESULTS

Study drug was discontinued due to mild thyroid dysfunction in 1 patient in the placebo vs. 3 in the amiodarone group (p=0.6). In linear mixed models there were significant effects of amiodarone on thyroid function tests, modified by follow-up visit (p<10(-9) for both TSH, T4, T3, fT4 and fT3). The amiodarone group had higher TSH, fT4 and T4 after 1 and 3months compared to placebo, whereas T3 and fT3 were lower. In all cases, the amiodarone-induced thyroid dysfunction was largest at 1month, declining at 3months, and with no differences at 6months, compared to baseline.

CONCLUSION

We found amiodarone to have a significant impact on thyroid function after only 1month, but with a fast recovery of thyroid function after amiodarone discontinuation. Our study indicates that short-term amiodarone can be considered safe in patients without prior thyroid dysfunction.

Differentiating Graves' disease from subacute thyroiditis using ratio of serum free triiodothyronine to free thyroxine

Background

The measurement of free thyroid hormone, instead of the total form, is more commonly used in current practice. We aimed to evaluate the usefulness of the ratio of serum free triiodothyronine (FT3, pg/mL) to free thyroxine (FT4, ng/dL) for differentiating Graves' disease from subacute thyroiditis.

Materials and methods

Medical records of thyrotoxic patients aged >15 years who had measurement of FT3, FT4 and thyrotropin on the first diagnosis of thyrotoxicosis before initiating treatment were retrospectively reviewed. Data were collected from all clinics, and were not limited to the endocrine clinic. Pregnant women were excluded.

Results

A total of 548 patients (468 with Graves' disease, 40 with subacute thyroiditis and 40 with toxic adenoma/multinodular goiter) were recruited. Mean age was 43.9 ± 15.4 years. Most were female 434 (79.2%), and goiter was present in 55.3%. Prevalence of T3-toxicosis and T4-toxicosis were 5.6% and 6.6%, respectively. Mean FT3/FT4 ratios were 4.62 ± 2 (10⁻² pg/ng) in patients with Graves' disease and 2.73 ± 0.5 in subacute thyroiditis. The area under the ROC curve of the FT3/FT4 ratio for diagnosis of Graves' disease was 0.83 (95%CI, 0.76–0.91). Cutoff level of this ratio >4.4 offered sensitivity of 47.2% and specificity of 92.8%.

Conclusions

FT3/FT4 ratio of >4.4 (10⁻² pg/ng) may help in differentiating the cause of thyrotoxicosis.

•

The ideal treatment of thyrotoxicosis should be directed at its etiology.

•

Serum total triiodothyronine (T3): thyroxine (T4) ratio (ng/ug) of >20 suggests Graves' disease.

•

In the current practice, the measurement of free thyroid hormone is more commonly used.

•

Serum free T3/free T4 ratio of >4.4 (10⁻² pg/ng) may help in differentiating the cause of thyrotoxicosis.

Establishment of reference intervals of thyroid function tests from cord blood of neonates in two selected hospitals, Addis Ababa, Ethiopia

BACKGROUND

Reference intervals are affected by different factors such as lifestyle, ethnicity, age/developmental stage, gender, nutrition and other environmental factors (Clin Biochem Rev: 29,2008). Therefore, it is obvious that it should be established for every population in different regions even within a country. Then the aim of this study is to establish population specific reference intervals of thyroid stimulating hormone, free thyroxine and free triidothyronine levels of cord blood.

RESULTS

One hundred twenty three cord blood samples collected from the umbilical cord of newborns were analyzed for thyroid stimulating hormone, free thyroxine and free triidothyronine values. The birth weights ranged between 2500 and 4700 g with mean (SD) value of 3241.46 (459.495) gram. Their gestational age ranged between 37 and 44 weeks with an average of 39.74 weeks. The 2.5(th) and 97.5(th) percentiles of values were found to be 3.48 mIU/L and 27.57 mIU/L for thyroid stimulating hormone, 0.89 ng/dl and 1.53 ng/dl for free thyroxine and 1.19 pg/ml and 2.51 pg/ml for free triidothyronine respectively.

CONCLUSION

In the present study the reference intervals of thyroid stimulating hormone, free thyroxine and free triidothyronine were established and based on the results obtained, were 3.48-27.56 mIU/L for thyroid stimulating hormone, 0.89-1.53 ng/dl for free thyroxine and 1.19-2.51 pg/ml for free triidothyronine. It has been concluded that the result can provide us with an important baseline to establish population specific reference intervals for our country using large scale studies.

Spectrum and Prevalence of Thyroid Disorders in Patients Admitted to the Anaesthesiology Outpatient Clinic for Surgery

OBJECTIVE

An anaesthetic approach and surgery are important treatment strategies in patients with thyroid dysfunction due to potential complications. We investigated the prevalence of thyroid disorders, the significance of thyroid function tests (TFTs) with respect to anaesthesia in the preoperative period and the need for routine examinations.

METHODS

A total of 10,600 patients who were admitted to the anaesthesiology outpatient clinic for surgery were retrospectively screened and enrolled between 2011 and 2013. Evident hypothyroidism was defined as free tetra-iodothyronine (fT4) <0.7 ng dL(-1) and thyroid-stimulating hormone (TSH) >4 mIU mL(-1), and subclinical hypothyroidism was defined as TSH >4 mIU mL(-1) with normal free hormone levels. Evident hyperthyroidism was defined as fT4 >1.7 ng dL(-1) and TSH <0.1 mIU mL(-1), and subclinical hyperthyroidism was defined as TSH <0.1 mIU mL(-1) with normal free hormone levels. Statistical analysis was conducted using the Statistical Package for the Social Sciences (SPSS) version 17.0. Independent samples t-test and one-way analysis of variance were used to compare the difference between groups.

RESULTS

Of the participants, 8.5% were found to have hypothyroidism, 2.5% had hyperthyroidism, 3.5% received treatment and 2.5% had their treatment postponed. The likelihood of hypothyroidism was greater among females, and no difference was found between genders with respect to hyperthyroidism.

CONCLUSION

We believe that TFTs are important because of regional factors. However, given the high cost of TFTs and because thyroid dysfunction risk increases with age, we concluded that routine TFTs in young patients with normal physical examination findings are not mandatory.