Thyroid-stimulating Hormone Assay Research Articles

Untreated thyroid autoantibody-negative SCH increases the risk of spontaneous abortions

BackgroundNumerous studies have found that subclinical hypothyroidism (SCH) may increase adverse pregnancy outcomes; however, the benefit of levothyroxine (LT4) treatment remains controversial. The 2017 guidelines of the American Thyroid Association weakly recommended LT4 therapy for serum antithyroid peroxidase antibody (TPOAb)-negative women with thyroid-stimulating hormone (TSH) concentrations greater than the pregnancy-specific reference range and below 10.0 mU/L. Therefore, the primary goal of this study was to investigate the correlation between thyroid autoantibody-negative SCH with or without LT4 treatment and adverse pregnancy outcomes.MethodsWe prospectively enrolled 1868 consecutive pregnant women. Finally, 1344 women were involved in the study according to the inclusion and exclusion criteria. Assays for TSH, free thyroxine (FT4), TPOAb, anti-thyroglobulin antibody, and laboratory indicators were performed. The participants were divided into the euthyroid (ET) group (n = 1250) and the SCH group(n = 94). The SCH group was further divided into LT4 group (n = 40) and non-LT4 group(n = 54). The laboratory indicators and pregnancy outcomes were evaluated during follow-ups.ResultsMaternal age, BMI, parity, and the history of spontaneous abortion did not differ significantly between the ET group and the different SCH groups. There were no significant differences in lipid profile and homocysteine levels between ET and SCH group in the first and third trimester of pregnancy. After adjusting the confounding factors, the non-LT4 group was a risk factor for spontaneous abortion (odds ratio: 3.141, 95% CI: 1.060–9.302). Survival analysis showed that the time of abortion was different between the ET group and SCH group (log-rank P= 0.042). The spontaneous abortion in SCH, especially in non-LT4, group mainly occurred in the first trimester of pregnancy.ConclusionsThyroid autoantibody negative-SCH seems to be associated with increased risk of spontaneous abortions during the first trimester of pregnancy. LT4 therapy in this patient population might be beneficial to reduce adverse pregnancy outcomes.

Cross-sectional prospective feasibility study of newborn screening for sickle cell anaemia and congenital hypothyroidism in Guyana

IntroductionNewborn screening (NBS) is a test done shortly after birth to detect conditions that cause severe health problems if not treated early. An estimated 71% of babies worldwide are born...

Immunoassay design and biotin interference.

Biotin (vitamin B7 or vitamin H), a member of vitamin B complex, acts as a cofactor for five biotin-dependent carboxylases, thus playing critical roles in gluconeogenesis, fatty acid synthesis and amino acid catabolism. Although rare inborn errors of metabolism may cause biotin deficiency, these can be successfully treated with biotin supplementation. In general, normal individuals do not get any benefit from taking biotin supplement. Nevertheless, biotin use remains widespread for growing healthy hair and nail. Unfortunately, the use/overuse of supplemental biotin may interfere with immunoassays that incorporate biotinylated antibody in assay design. Biotin if present in elevated concentration in serum or plasma, may falsely increase analyte concentration using competitive immunoassay (positive interference). In contrast, biotin shows negative interference if sandwich immunoassay format is used. Such interferences may cause diagnostic error, most commonly in cases of hyperthyroidism due to (1) positive interference of biotin in free triiodothyronine (FT3) and free thyroxine (FT4) assays (competitive format) and (2) negative interference in thyroid stimulating hormone (TSH) assay (sandwich format). In this review, I explore the biochemistry of biotin and discuss its role as a potential interferent in immunoassay formats that are biotin based.

Analytical validation of the LiCA® high-sensitivity human thyroid stimulating hormone assay

BackgroundWe aimed to assess the analytical characteristics of a new high-sensitivity human thyroid stimulating hormone (hTSH) assay on a light-initiated chemiluminescent immunoassay system (LiCA Smart) and examine the utility of this assay in the context of profoundly low TSH levels (<0.01 mIU/L). MethodsAnalytical validations included precision, linearity, reportable range, analytical sensitivity, interference, reagent lot-to-lot and between-instrument variability, and method comparisons. Additionally, a cross-sectional study was performed to evaluate the assay for the detection of profoundly low TSH levels in comparison to those of two other ultrasensitive hTSH assays. ResultsWithin-run and within-lab imprecisions (%CV) were < 5% at all concentrations studied. A satisfactory linearity (R = 0.998, change in recovery < 5%) was verified over the entire measuring range. Method comparisons demonstrated a reasonable agreement (R > 0.99, median bias < 5%) between LiCA and Cobas, ADVIA, UniCel or Architect. The limit of quantitation was 0.0019 mIU/L. Comparative measurements of 236 patient samples with profoundly low TSH levels (<0.01 mIU/L) by LiCA, Cobas, and Architect revealed that the detection rate observed with LiCA (67.8%) was significantly higher than that with Cobas (28.0%) or Architect (21.7%). In a further comparative follow-up of patients with overt hyperthyroidism who were receiving treatment, an earlier recovery response of TSH was observed in LiCA. ConclusionsThe LiCA Smart hTSH is a precise and highly sensitive fourth-generation assay. The assay demonstrated superior detection sensitivity for profoundly low TSH levels and was acceptable for clinical use.

Comparison of Enzyme-Linked Immunosorbent Assay and Chemiluminescence Immunoassay for Thyroid Stimulating Hormone Analysis in Tertiary Care Hospital Lahore

Objective: To compare enzyme-linked immunosorbent assay and Chemiluminescence immunoassay for thyroid stimulating hormone analysis in human serum. &#x0D; Methodology: This cross-sectional study conducted from 17th March till 13th June. In Punjab Rangers Teaching Hospital, Lahore after approval from Institutional Review Board. Random samples from both genders, between 18-70 years of age were included. Haemolysed, lipemic or icteric specimens were excluded. The sera were assayed for thyroid stimulating hormone (TSH) by enzyme-linked immunosorbent assay (ELISA) and Chemiluminescence immunoassay (CLIA). Data was analyzed by SPSS 24.&#x0D; Results: A total of one hundred and ninety-eight serum samples were processed by ELISA and CLIA in all the samples, with more females as compared to males (1:1.3). ELISA technique identified 134 subjects as Euthyroid, 40 Hypothyroid and 24 Hyperthyroid, while 122 Euthyroid, 48 hypothyroid and 28 hyperthyroid subjects by CLIA. Thyroid stimulating hormone (TSH) levels reference range was taken 0.4-4.5mU/L according to American Thyroid Association. Mean ± SD of TSH was 1.45 ± 0.79; 12.27 ± 11.03 and 0.23 ± 0.17 mU/L respectively by ELISA whereas CLIA indicated Mean ± SD to be 1.93 ± 0.936, 16.04 ± 14.68 and 0.393 ± 0.375 mU/L respectively for Euthyroid, hypothyroid and hyperthyroid. Correlation of coefficient (R2 =0.89) was found significantly positive between both methods. There was a significant difference in hypothyroid and Euthyroid groups.&#x0D; Conclusion: TSH assay by CLIA has shown a wider range of functionality, throughout and borderline cases were identified better as compared to ELISA. Turn-around-time (TAT) decreased, physician satisfaction increased and indirectly benefitting patient treatment and prognosis.

Thyroid Disorders.

Thyroid Disorders.

Age- and sex-specific reference intervals for thyroid hormones in a Chinese pediatrics: a prospective observational study of 1,279 healthy children.

BackgroundThyroid hormones are essential for early neurocognitive development and growth and development in childhood and adolescence. However, the reference intervals (RIs) for thyroid hormones in Chinese pediatric individuals remain unclear. This study aimed to establish thyroid hormone RIs for a Chinese pediatric population according to appropriate age- and sex-specific partitioning.MethodsIn this prospective observational study, a total of 1,279 healthy children (singletons, aged from 1 day to 12 years) were recruited, and serum samples were analyzed on a Mindray automated chemiluminescence immunoassay analyzer CL-6000i for thyroid hormone detection, including thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), free thyroxine (FT4), total triiodothyronine (T3), and total thyroxine (T4). Age and sex-specific RIs were established, and the corresponding 95% confidence intervals (CIs) were calculated in accordance with the Clinical Laboratory Standards Institute (CLSI) document C28-A3 guidelines.ResultsQuantile testing revealed that the median (P50) and RIs [2.5th percentile (P2.5)–97.5th percentile (P97.5)] for TSH, FT3, T3, and T4 of males differed significantly from those of females (P<0.05), except for FT4 (P=0.483). For FT3 and T3, the RIs of males were higher than that of females, and the RI of T4 for males was narrower and higher than that of females [P2.5–P97.5: 72.33–171.60 vs. 72.31–176.27 nmol/L; P50: 116.75 vs. 113.47 nmol/L, P=0.011]. RIs for TSH, FT3, FT4, T3, and T4 showed sex- and age-specific properties and displayed a wide variation during the first month of life but gradually narrowed and concentrated with increasing age. In addition, RIs of TSH, FT3, FT4, and T3 in males differed significantly from females in the first month of life (TSH: 1.46–10.87 vs. 1.08–11.35 mIU/L; FT3: 2.96–7.08 vs. 2.35–7.27 pmol/L, FT4: 13.34–28.65 vs. 13.82–31.83 pmol/L; T3: 0.83–2.33 vs. 0.72–2.46 nmol/L). The RI of T4 also exhibited a difference between males and females in the 9- to 12-year age group (59.31–150.72 vs. 63.29–146.94 pmol/L for males and females, respectively).ConclusionsPediatric RIs of thyroid hormones display age- and sex-specific trends. The RIs established in this study will improve the accuracy of TSH assay result interpretations and clinical decision-making in clinical laboratories that utilize the Mindray analytical platform.

Samples spiked with pituitary-derived thyroid-stimulating hormone may disguise the extent of differences between thyroid-stimulating hormone assays.

A large discordance in the diagnosis and potential management of hypothyroidism using Abbott and Roche thyroid assays has been reported recently. The difference in Abbott and Roche thyroid-stimulating hormone (TSH) results in these studies was larger than anticipated from the external quality assessment (EQA) reports. Abbott and Roche TSH method means in UK NEQAS for thyroid hormones distributions 430 to 454 were compared against the amount of TSH spiked. A TSH deplete serum pool was spiked with various concentrations of pooled high TSH serum and 3rd WHO International Standard for TSH (WHO-IS). Four serum pools with TSH close to clinical decision limits were spiked with two concentrations of WHO-IS. On review of EQA data, median (IQR) Roche: Abbott TSH ratio was lower (p < 0.001) in 48 pools spiked with TSH (1.11 (1.07-1.16)) compared to 41 pools not spiked (1.29 (1.25-1.31)) and the decrease was proportionate to the contribution of spiked TSH to total TSH in the samples (ρ=-0.908, p < 0.001). In spiking experiments, the relationship of Roche and Abbott TSH was different in TSH deplete pool spiked with WHO-IS (RocheTSH=1.13*AbbottTSH-0.52) and high TSH serum (RocheTSH=1.43*AbbottTSH-0.50), respectively. The Roche: Abbott TSH ratio decreased and the method agreement improved on spiking serum pools with WHO-IS. Abbott and Roche TSH assays are not in harmony in human serum samples but the agreement was better in samples spiked with WHO-IS which contains pituitary-derived TSH. Use of pituitary-derived TSH spiked samples, such as provided by EQA schemes, may mask clinically significant between-assay differences.

The role of thyroid stimulating hormone in the timing of thyroxin supplement after thyroid operations

Thyroid Stimulating Hormone (TSH) levels can be measured accurately down to a very low serum concentration with an immunoassay. When the serum TSH level is in the normal range, measuring the T3 and T4 levels is redundant. The objective of this study is to study the relation of TSH levels postoperatively in thyroid surgeries with the timing for thyroxin treatment as a supplemental and suppressive therapy. A prospective cohort study was done on 84 patients underwent thyroid operations in Al-Yarmouk Teaching Hospital from March 2010 through November 2012. Patients underwent different thyroid operations (lobectomy, subtotal thyroidectomy and total thyroidectomy) for different thyroid pathology. Later, they were followed up by TSH assay in periods of 2, 4, 6 and 12 months postoperatively. Variables were compared by using the analysis of variance, ANOVA test. P – values equal or less than 0.05 and 0.01 were considered to be statistically significant and highly significant, respectively. The mean age of patients was 43.30 ± 10.19 years. The females made the vast majority of study sample (85.7%). Patients were divided into six groups: simple colloid goiters (17 patients), multinodular goiters (32 patients), solitary thyroid nodules (11 patients), Hashimoto’s thyroiditis (8 patients), Graves’ disease (8 patients) and papillary and follicular carcinomas (8 patients). The study revealed that all patients with malignant thyroid nodules (i.e. those with total thyroidectomies) and the vast majority of patients with Hashimoto’s thyroiditis were in definite need for thyroxin treatment post-operatively. Other patients were variable in their need and timing of treatment according to the histopathological results and the type of operations. In conclusion; measurement of TSH level postoperatively is a good indicator for need of thyroxin treatment and for dose adjustment with the help of pathological results and the type of surgery.

Prevalence of Thyroid Dysfunction and Anti–thyroid Peroxidase Antibody in Gestational Diabetes Mellitus

Background: Gestational diabetes mellitus (GDM) and thyroid dysfunction are the two common endocrine disorders affecting pregnancy. Some association was hypothesized between GDM and thyroid dysfunction in the literature. The main aim of this study was to unveil this metabolic interplay as better understanding may facilitate early diagnosis and intervention thereby limiting major fetal and maternal adverse events. Here we estimated the prevalence of abnormal thyroid function and anti–thyroid peroxidase (anti-TPO) antibody and also studied the risk factors for thyroid disorders in patients with GDM. Materials and Methods: This cross-sectional study was conducted between February 2014 and January 2015. A total of 100 consecutive pregnant women diagnosed to have GDM as per the American Diabetes Association 2013 recommendations were recruited and thyroid stimulating hormone, free triiodothyronine (T3), free thyroxine (T4), and anti-TPO antibody assays were done. Details regarding pregnancy outcome and any complications if present were also obtained and analyzed. The prevalence is expressed as proportions, and the statistical significance of risk factors was assessed using the chi-square test and independent t-test. Results: Abnormal thyroid function was detected in 31 (31%) patients, which includes 17 cases of subclinical hypothyroidism (54%), 10 hypothyroidism (32%), 2 (6%) subclinical hyperthyroidism, and one case each of isolated low T3 and isolated low T4. Anti-TPO antibody was positive in 35 patients (35%). History of GDM in previous pregnancy, family history of diabetes mellitus, presence of clinically detectable thyroid gland enlargement, and presence of anti-TPO antibody in serum were found to increase the risk of thyroid dysfunction. Majority of the subjects had uneventful delivery, and no significant increase in maternal or fetal complications was reported. Conclusions: This study showed a high prevalence of thyroid dysfunction and anti-TPO antibody in GDM patients. The significant thyroid abnormalities detected were subclinical hypothyroidism and hypothyroidism. The risk of thyroid dysfunction is elevated in patients with the presence of anti-TPO antibody. This scenario provides a strong ground to recommend meticulous assessment of thyroid function in GDM patients.

Palpitations and Fatigue Post COVID: A Harbinger of Silent Thyroiditis!

Background: Subacute thyroiditis is a self-limiting condition brought about by an inflammatory reaction often linked to a recent viral infection. SARS-COV2 (COVID-19), an RNA coronavirus that started a global pandemic in December 2019 has been linked mostly to severe acute respiratory distress syndrome. However, there have been increasing reports of its effect on other organ systems. We present a case of a 32-year-old female recovering from COVID-19, only to develop silent thyroiditis afterwards. Clinical Case: A 32-year-old female with anxiety disorder but otherwise in excellent health was diagnosed with COVID-19 via nasal swab RT-PCR after experiencing low grade fever and cough. She quarantined at home and was on her way to recovery when, a few weeks later, she began to experience increasing bouts of chest pain with no relation to activity, intermittent headaches and lower extremity edema. This prompted her to visit the emergency department. Work-up done at that time was unremarkable and her symptoms were attributed mostly to anxiety. She was advised to follow-up as an outpatient with a cardiologist. One month later, due to the persistence of her fatigue, low exercise tolerance and tremors, she decided to seek consult with a cardiologist. An electrocardiogram done during that visit showed normal sinus rhythm with poor-R wave progression and early repolarization changes. Both the echocardiogram and 24-hour Holter monitoring, which were subsequently done, were unremarkable. Blood work-up, however, revealed a significantly low thyroid stimulating hormone (TSH) level of 0.17 mU/L, for which she was referred to an endocrinologist. A month later, she sought consult with an endocrinologist. Thyroid gland was non-tender on palpation. Repeat blood work-up showed an elevated TSH level (23.50 mU/L) with a low Free T4 (0.42 ng/dL) and an elevated thyroid peroxidase antibody (TPO-Ab) level (900 mU/mL), indicative of subacute thyroiditis, but without associated neck pain. Thyroid sonography done showed diffusely heterogeneous thyroid lobes with no evidence of a dominant mass or nodule. A decision was made to start her on low dose levothyroxine. Two months into treatment, she underwent repeat thyroid hormone levels. Normal TSH and normal free T4 were observed. However, TPO-Ab was still elevated. It was decided to continue her therapy for one more month before gradually tapering her levothyroxine dose. She was told to follow-up in a month for further monitoring. Conclusion: Subacute thyroiditis associated with COVID-19 infection has become a more common occurrence as more cases of COVID-19 are noted worldwide. Our patient followed the usual course of subacute thyroiditis, initially presenting with a thyrotoxicosis phase which typically lasts 4-10 weeks, then subsequently developing hypothyroidism, inadvertently needing thyroid hormone replacement. What made this case more intriguing was that she did not have severe anterior neck pain, the classic clinical presentation of subacute thyroiditis. While there is a very strong association between COVID-19 and respiratory failure, there is paucity of evidence linking COVID-19 to dysfunction of other body systems. This case of thyroiditis presenting post COVID-19 illness, buttresses the versatility of COVID-19. Physicians should keep this in mind when evaluating a COVID-19 survivor who continue to present with persistent tachycardia or palpitations with or without anterior neck pain even after a month or two from infection. Routine follow-up TSH assay on COVID-19 survivors may be a valuable consideration.

Frequency of Pathological Types of Hyperthyroidism in Thyroid Scan Patients.

Hyperthyroidism is a common systemic disorder where Graves' disease is known as the leading cause of the disease. Thyroid stimulating hormone, T4 and T3 antibody assay is usually performed for the diagnosis of the pathology. However, with uncertainty in the results and in order to estimate the magnitude and the exact cause of the disease, radioactive iodine uptake (RAIU) test is recommended. The aim of this study is to evaluate underlying pathology in the patients presenting hyperthyroidism using RAIU test results. This is a cross-sectional retrospective study conducted on the patients with hyperthyroidism referred to Shahid Madani Hospital in Khorramabad. Data regarding the biochemical analysis and RAIU test was collected from the records and a questionnaire based on demographic and clinical information was completed for each patient. Of 137 patients presenting hyperthyroidism, 62.04% presented with Graves' disease, 24.08% with toxic multinodular goiter and 13.86% with toxic adenoma. 24-hour RAIU test showed that the percent of radioiodine uptake was most in toxic adenoma with 67.7%, Graves' disease 53.5% and multinodular goiter 39%, respectively. From the age-based analysis, we found that Graves' was most common in 20-30 years old individuals accounting for 34%, multinodular goiter in 50+ aged individuals with 36.3% and toxic adenoma was most prevalent in 30-40 and 50+ aged patients, with 26.3%. In our population of interest, 81.8% toxic multinodular goiter patients were females. Our study presents the outcome of RAIU tests in hyperthyroidism based on the underlying pathologies. We also conclude, in light of other findings, that Graves' disease is the most common cause of hyperthyroidism in our population.

Utilization of indirect calorimetry to assist in determining undiagnosed hypothyroidism in a patient on mechanical ventilation.

Published predictive equations are required when indirect calorimetry (IC) is unavailable in the clinical setting. Several medical conditions that are not accounted for by published predictive equations can impact a patient's resting energy expenditure, such as adrenal changes or alterations in thyroid-stimulating hormone (TSH). TSH levels significantly impact a patient's resting energy expenditure, with hypothyroidism decreasing and hyperthyroidism increasing energy requirements. Clinical hypothyroidism has been correlated with increased ventilator dependency in patients with critical illness and malnutrition. The following case study describes the utilization of IC to trigger a full evaluation for the diagnosis of hypothyroidism in an adult patient with multiple myeloma who was mechanically ventilated. IC results for this patient were 39% lower than estimated by predictive energy equations. TSH, thyroxine, and triiodothyronine serum assays were obtained to rule out hypothyroidism. Based on elevated TSH and low thyroxine, the patient was found to have undiagnosed hypothyroidism. Appropriate pharmaceutical and nutrition interventions were made based upon these results. This case demonstrates the impact hormonal changes can have on resting energy expenditure and how the utilization of IC can provide additional information other than energy requirements.

Analytical Variation Between Two Different TSH Reagents from the Same Manufacturer.

Thyroid stimulating hormone (TSH) immunoassays are known for giving varying results based on the platform of testing and the generation of kit used. It is generally expected that the results should not vary to affect clinical diagnosis and management. We aimed to perform method comparison study between two TSH assays by the same manufacturer Siemens Healthineers. Results show that there is a large proportional error between the assays with a bias of -3.71mIu/L indicating that TSH assay gives higher values for TSH for the same patient as measured against the TSH3-Ultra kit. This can affect interpretation of results leading to false increase in patients categorized under hypothyroidism and subclinical hypothyroidism. We strongly suggest, to prevent errors in clinical evaluation of a patient with thyroid dysfunction, validation of the performance of the assay and method comparison should be performed in-house.

The diagnosis and management of subclinical hypothyroidism is assay-dependent- Implications for clinical practice.

We assessed the commutativity of Roche and Abbott thyroid assays in the diagnosis and management of subclinical hypothyroidism (SCH). The Roche and Abbott thyroid assays are used by approximately 75% of clinical laboratories in the UK. Consecutive samples received from primary care on patients with SCH who had a raised thyroid-stimulating hormone (TSH) <10mIU/L and a normal free thyroxine (fT4) from two laboratories using either Roche or Abbott thyroid assays were identified over 10 working days. Following identification, samples were analysed at the other site within 24hours. Diagnostic and management discordance were studied using the relevant manufacturer-provided reference ranges. We identified 93 patients with SCH (53 using the Roche assay). Roche TSH and fT4 results were respectively 40%±15% and 16%±7% higher (P<.001) compared to Abbott results. Of the 93 patients, 41 (44%) were concordant for SCH on both methods. Of the 53 patients with SCH on the Roche assays, 40 (75.5%) had normal thyroid function and 13 (24.5%) had SCH when analysed using the Abbott assays. Of the 40 patients with SCH on the Abbott assays, 28 (70%) had SCH and 12 (30%) had results indicative for levothyroxine replacement when analysed on the Roche assays. Of these 12 patients, four had TSH>10mIU/L, five had low fT4 and three had both. The diagnosis and management of SCH is strikingly different when using TSH and fT4 assays provided by Abbott Laboratories and Roche Diagnostics. Clinicians and laboratorians should be aware that between-assay differences and variations in reference ranges will directly impact the diagnosis and management of subclinical hypothyroidism.

Recent evidence sets therapeutic targets for levothyroxine-treated patients with primary hypothyroidism based on risk of death.

Since the introduction of sensitive assays for serum thyroid-stimulating hormone (TSH) clinicians have advised hypothyroid patients to adjust the dose of levothyroxine (L-T4) in order to achieve a normal serum TSH. A minority of patients are dissatisfied with this treatment strategy and experience symptoms. Some indirect evidence suggests that a normal serum TSH may not necessarily reflect euthyroidism at the tissue level in patients treated with L-T4. Increasingly hypothyroid patients demand higher doses of L-T4 or liothyronine (L-T3) or animal thyroid extract, often purchased online, and titrate the dose against symptoms, although ample evidence suggests that combination treatment (L-T4 with L-T3) is no more effective than L-T4 alone. Community surveys show that up to 53% of treated hypothyroid patients at any time have a serum TSH outside the normal range. The recommendation by guidelines that the upper limit of the normal range for serum TSH should not be exceeded is supported by robust evidence and is generally accepted by clinicians and patients. However, until recently the lower limit of serum TSH for optimal L-T4 replacement has been controversial. New evidence obtained by two independent large population studies over the past two years has shown that mortality of hypothyroid patients treated with levothyroxine is increased when the serum TSH exceeds or is reduced outside the normal reference range. It is estimated that the implementation of a policy of normalising serum TSH in hypothyroid patients will reduce the risk of death of 28.3 million people in the USA and Europe alone.

VALIDATION OF CHEMILUMINESCENT ASSAY FOR CANINE THYROID STIMULATING HORMONE IN RED PANDAS (AILURUS FULGENS FULGENS).

Thyroid abnormalities have been anecdotally reported in red pandas (Ailurus fulgens fulgens); however, definitive diagnosis is hampered by a lack of established reference ranges and validated diagnostic tests. The chemiluminescent assay for canine thyroid stimulating hormone (cTSH) has been validated for use in domestic canids and felids. This study aims to validate the cTSH assay for use in red pandas. Validation was performed via serial dilutions of banked serum samples (n = 15) and both inter- and intra-assay testing. High estimated recoveries and low coefficients of variability indicate that the cTSH assay accurately and consistently measures TSH concentrations in red panda serum. Further studies to generate red panda age and sex TSH reference ranges are indicated.

Delayed Diagnosis of Congenital Hypothyroidism in a Child with Trisomy 21 and Biotinidase Deficiency and Successful Use of Levothyroxine Sodium Oral Solution

Endocrine disorders are more common and appear earlier in people with trisomy 21 (T21) than in the general population, with thyroid dysfunction being the most common, including both congenital and acquired hypothyroidism. The treatment for biotinidase deficiency, a condition that occurs in approximately 1 : 110,000 people, is with biotin (vitamin B7) supplementation. However, biotin can interfere with endocrine laboratory assays and cause falsely low thyroid-stimulating hormone (TSH) and elevated free thyroxine (FT4) levels. This can interfere with the timely diagnosis and subsequent treatment of congenital hypothyroidism (CH). This case report describes an infant with partial biotinidase deficiency that was confirmed on day 10 of life. Routine screening erroneously reported “normal” TSH that caused delayed diagnosis of CH due to interference with the TSH assay from concurrent biotin use. Once the biotin treatment was withheld for 4 days and the thyroid function tests repeated, an elevated TSH became apparent. Treatment with tablet levothyroxine (L-T4) was started and subsequently changed to L-T4 oral solution (Tirosint®-SOL) to overcome treatment administration difficulties encountered with the tablet form. This resulted in improved TSH control due to more accurate and consistent dosing compared with the tablet formulation. This is the first report of the use of L-T4 oral solution in an infant with T21 and biotinidase deficiency.

Hypothyroidism Presenting as Recurrent Syncopal Attacks: A Missed Diagnosis

Myxedema coma is a severe hypothyroidism which usually occurs due to long-standing, undiagnosed, or untreated hypothyroidism. Fortunately, Myxedema coma is now a rare presentation of hypothyroidism, likely due to earlier diagnosis as most of physicians are familiar with classic signs and symptoms of hypothyroidism and widespread availability of thyroid-stimulating hormone (TSH) assays. However it might be associated with several cardiac arrhythmias including; sinus bradycardia, ventricular tachycardia, and torsade de pointes. We report a case of a 53 year old female who presented with several episodes of syncope that was associated with intermittent torsade de pointes found to have severe hypothyroidism with complete reversal of her symptoms after she was started on thyroid hormonal replacement.

Small for gestational age is a risk factor for thyroid dysfunction in preterm newborns

BackgroundThyroid hormones play an important role in the normal growth and maturation of the central nervous system. However, few publications addressed the altered thyroid hormone levels in preterm small for gestational age (SGA) newborns. We hypothesized preterm SGA infants have higher thyroid-stimulating hormone (TSH) concentrations than appropriate for gestational age (AGA) ones within the normal range and an increased incidence of thyroid dysfunction.MethodsThe study was designed to compare thyroid hormone levels within the normal range and the incidence of thyroid dysfunction in the SGA and AGA groups to test the hypothesis. The medical records of all preterm infants admitted to the neonatal intensive care unit (NICU) at the First Affiliated Hospital of Shantou University Medical College, Shantou, China, between January 1, 2015 and December 31, 2018, were reviewed. Blood samples were collected between 72 and 96 h of life and analyzed with TSH, free thyroxine (FT4) and free triiodothyronine (FT3) assays. Thyroid function test (TFT) results, and neonatal demographic and clinical factors were analyzed to identify the associations between SGA birth and altered thyroid concentrations and thyroid dysfunction.ResultsTSH and FT4 concentrations were significantly higher in the SGA group than the AGA group ((3.74(interquartile range (IQR):2.28 ~ 6.18) vs. 3.01(IQR: 1.81 ~ 5.41) mU/L, p = 0.018), and (17.76 ± 3.94 vs. 17.42 ± 3.71 pmol/L, p = 0.371), respectively). The higher TSH levels were associated with being SGA or Z-score of birth weight (BW) for GA after adjusting for potential confounders ((βSGA = 0.68 (95% confidence interval (CI) 0.15 ~ 1.21), p = 0.013) or (βZ-score = − 0.25 (95%CI -0.48 ~ − 0.03), p = 0.028), respectively). However, we did not find a significant association between SGA birth and altered FT4 concentrations. Furthermore, compared with the AGA group, the SGA group presented an increased incidence of transient hypothyroxinemia with delayed TSH elevation (dTSHe), a higher percentage receiving levothyroxine (L-T4) therapy, and a higher rate of follow-up within the first 6 months of life.ConclusionsPreterm SGA newborns had significantly higher TSH concentrations within the normal range and an increased incidence of thyroid dysfunction. The SGA newborns with these features should be closely followed up with periodical TFTs and endocrinologic evaluation.