Assessment of Individual and Mixed Effects of Six Minerals on Thyroid Hormones in Chinese Pregnant Women.

The biosynthesis of thyroid hormones is essential for brain and neurological development. It requires iodine as a key component but is also influenced by other nutrients. Evidence for the combined nutrient status in relation to thyroid hormones during pregnancy is limited. We aimed to investigate the joint associations of iodine, selenium, zinc, calcium, magnesium and iron with maternal thyroid functions in 489 pregnant women from Hangzhou, China. Serum levels of six essential minerals and thyroid function parameters were measured during the first antenatal visit. Linear regression, quantile g-computation and Bayesian kernel machine regression were used to explore the individual and joint relationships between the six minerals and thyroid hormones. Linear regression analyses revealed that calcium was positively associated with free triiodothyronine (FT3). Zinc was positively associated with free thyroxine (FT4). Iodine was negatively associated with thyroid-stimulating hormone (TSH) and positively associated with FT3 and FT4. The quantile g-computation and BKMR models indicated that the joint nutrient concentration was negatively associated with TSH and positively associated with FT3 and FT4. Among the six minerals, iodine contributed most to thyroid function. The findings suggested that maintaining the appropriate concentration of minerals, either as individuals or a mixture, is important for thyroid health during pregnancy.

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

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

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.

The optimal healthy ranges of thyroid function defined by the risk of cardiovascular disease and mortality: systematic review and individual participant data meta-analysis.

BACKGROUND: Reference intervals of thyroid-stimulating hormone (TSH) and free thyroxine (FT4) are statistically defined by the 2·5-97·5th percentiles, without accounting for potential risk of clinical outcomes. We aimed to define the optimal healthy ranges of TSH and FT4 based on the risk of cardiovascular disease and mortality. METHODS: This systematic review and individual participant data (IPD) meta-analysis identified eligible prospective cohorts through the Thyroid Studies Collaboration, supplemented with a systematic search via Embase, MEDLINE (Ovid), Web of science, the Cochrane Central Register of Controlled Trials, and Google Scholar from Jan 1, 2011, to Feb 12, 2017 with an updated search to Oct 13, 2022 (cohorts found in the second search were not included in the IPD). We included cohorts that collected TSH or FT4, and cardiovascular outcomes or mortality for adults (aged ≥18 years). We excluded cohorts that included solely pregnant women, individuals with overt thyroid diseases, and individuals with cardiovascular disease. We contacted the study investigators of eligible cohorts to provide IPD on demographics, TSH, FT4, thyroid peroxidase antibodies, history of cardiovascular disease and risk factors, medication use, cardiovascular disease events, cardiovascular disease mortality, and all-cause mortality. The primary outcome was a composite outcome including cardiovascular disease events (coronary heart disease, stroke, and heart failure) and all-cause mortality. Secondary outcomes were the separate assessment of cardiovascular disease events, all-cause mortality, and cardiovascular disease mortality. We performed one-step (cohort-stratified Cox models) and two-step (random-effects models) meta-analyses adjusting for age, sex, smoking, systolic blood pressure, diabetes, and total cholesterol. The study was registered with PROSPERO, CRD42017057576. FINDINGS: We identified 3935 studies, of which 53 cohorts fulfilled the inclusion criteria and 26 cohorts agreed to participate. We included IPD on 134 346 participants with a median age of 59 years (range 18-106) at baseline. There was a J-shaped association of FT4 with the composite outcome and secondary outcomes, with the 20th (median 13·5 pmol/L [IQR 11·2-13·9]) to 40th percentiles (median 14·8 pmol/L [12·3-15·0]) conveying the lowest risk. Compared with the 20-40th percentiles, the age-adjusted and sex-adjusted hazard ratio (HR) for FT4 in the 80-100th percentiles was 1·20 (95% CI 1·11-1·31) for the composite outcome, 1·34 (1·20-1·49) for all-cause mortality, 1·57 (1·31-1·89) for cardiovascular disease mortality, and 1·22 (1·11-1·33) for cardiovascular disease events. In individuals aged 70 years and older, the 10-year absolute risk of composite outcome increased over 5% for women with FT4 greater than the 85th percentile (median 17·6 pmol/L [IQR 15·0-18·3]), and men with FT4 greater than the 75th percentile (16·7 pmol/L [14·0-17·4]). Non-linear associations were identified for TSH, with the 60th (median 1·90 mIU/L [IQR 1·68-2·25]) to 80th percentiles (2·90 mIU/L [2·41-3·32]) associated with the lowest risk of cardiovascular disease and mortality. Compared with the 60-80th percentiles, the age-adjusted and sex-adjusted HR of TSH in the 0-20th percentiles was 1·07 (95% CI 1·02-1·12) for the composite outcome, 1·09 (1·05-1·14) for all-cause mortality, and 1·07 (0·99-1·16) for cardiovascular disease mortality. INTERPRETATION: There was a J-shaped association of FT4 with cardiovascular disease and mortality. Low concentrations of TSH were associated with a higher risk of all-cause mortality and cardiovascular disease mortality. The 20-40th percentiles of FT4 and the 60-80th percentiles of TSH could represent the optimal healthy ranges of thyroid function based on the risk of cardiovascular disease and mortality, with more than 5% increase of 10-year composite risk identified for FT4 greater than the 85th percentile in women and men older than 70 years. We propose a feasible approach to establish the optimal healthy ranges of thyroid function, allowing for better identification of individuals with a higher risk of thyroid-related outcomes. FUNDING: None.

Technical Note: Approach to Identify and Eliminate Biotin Interference in Thyroid Function Tests Using Beckman DXI 800 Analyzer by Taking Advantage of Assay Harmonization with Alinity i Analyzer.

OBJECTIVE: We reported significant interference of biotin in FT3 and FT4 assays using Beckman DXI 800 analyzer. Recently we acquired Alinity i analyzer where TSH, FT3 and FT4 assays are not biotin based. We hypothesized that if thyroid function tests on DXI 800 and Alinity i are harmonized, then it is possible to eliminate biotin interference. METHODS: We investigated assay harmonization by analyzing 35 specimens for TSH, FT4 and FT3 using both analyzers. We prepared one serum pool using left-over specimens where thyroid tests were ordered. Then aliquots of the pool were supplemented with various amounts of biotin followed by measuring thyroid function tests again. RESULTS: We observed assay harmonization between both analyzers for TSH, FT3 and FT4 Tests. TSH assay was not affected in the presence of biotin, but FT3 and FT4 values were significantly elevated using DXI 800 analyzer. In contrast, TSH, FT3 and FT4 assays were not affected by biotin using Alinity i analyzer. CONCLUSIONS: Elevated FT3 and FT4 using DXI 800 analyzer may be due to biotin interference which can be eliminated by observing normal values using Alinity i analyzer. However, normal or slightly elevated TSH with elevated FT3 and FT4 using both analyzers may indicate rare type of TSH producing tumor of pituitary, not biotin interference.

An update: maternal iodine supplementation, thyroid function tests, and child neurodevelopmental outcomes.

PURPOSE OF REVIEW: The impact of maternal iodine supplementation (MIS) during pregnancy on thyroid function and child neurodevelopmental outcomes in areas of mild-to-moderate iodine deficiency (MMID) remains unclear. RECENT FINDINGS: Despite growing success of salt iodization programs, a 2022 meta-analysis found that 53% of pregnant patients worldwide continue to have insufficient iodine intake during pregnancy. A 2021 randomized controlled trial (RCT) found that MIS in women with mild iodine deficiency led to iodine sufficiency and positive effects on maternal thyroglobulin. A 2021 cohort study of MIS initiated prior to pregnancy was associated with lower thyroid-stimulating hormone (TSH), higher FT3, and FT4. Other cohort studies, however, found that neither salt iodization nor MIS were adequate to meet pregnancy iodine needs. Data have been mixed regarding maternal iodine status and pregnancy outcomes in patients of MMID. Meta-analyses have not shown any clear benefit on infant neurocognitive outcomes with MIS of MMID patients. A 2023 meta-analysis found that the prevalence of excess iodine intake in pregnancy was 52%. SUMMARY: MMID continues to exist during pregnancy. Salt iodization alone may be insufficient to ensure adequate iodine status during pregnancy. There is an absence of high-quality data to support routine MIS in areas of MMID. However, patients with specialized diets (vegan, nondairy, no seafood, noniodized salt, and so on) may be at risk for inadequate iodine status in pregnancy. Excess iodine intake can be detrimental to the fetus and should be avoided during pregnancy.

Association between serum-free thyroxine level and all-cause mortality in critically ill patients: a retrospective study from MIMIC-IV.

Background: Low thyroxine (T4) levels have been observed in critically ill patients; however, controversial results regarding T4 supplemental therapy are reported. The association between serum free T4 (FT4) levels and mortality in critically ill patients has not been fully established and needs to be clarified. Methods: Data from the Medical Information Mart for Intensive Care (MIMIC)-IV were collected and analyzed. The association between FT4 level and 30-day mortality after ICU admission was analyzed using Kaplan-Meier curves, spline smoothing fitting, martingale residuals of the null Cox model, and restricted cubic spline (RCS). Logistic regression, Cox regression, and receiver operating characteristic curve (ROC) were used to uncover the relationship and predictive value of serum FT4 and 30-day mortality in critically ill patients. Results: In the final analysis, 888 patients were enrolled, and the serum FT4 levels were divided into four groups. A significant difference in 30-day mortality was observed between the four groups. Kaplan-Meier curves also presented significantly higher 30-day mortality in groups 1 and 2 (p < 0.0001). Further multivariance logistic regression showed that group 1 with FT4 levels lower than 0.7 µg/dl can predict 30-day mortality (odds ratio (OR) = 3.30, 95% confidence interval (CI) = 1.04-11.31). Spline smoothing fitting analysis showed a "V"-shaped line between 30-day mortality and FT4 level within 0-3 µg/dl. Further RCS analysis showed that the risk of death decreased rapidly as FT4 levels increased when serum FT4 levels were lower than 1.2 µg/dl and started to become flat afterward. The area under the ROC of the lower FT4 level to predict 30-day mortality was 0.833 (95% CI = 0.788-0.878). Both multivariant Cox regression and logistic regression showed that FT4 levels lower than 1.2 µg/dl can independently predict 30-day mortality when adjusted for other potential confounders (HR = 0.34, 95% CI = 0.14-0.82; OR = 0.21, 95% CI = 0.06-0.79, respectively), but its predictive power disappeared when adjusted for T3 or total T4. Conclusion: Serum FT4 levels were significantly negatively associated with 30-day mortality when they were lower than 1.2 µg/dl and could predict the risk of 30-day mortality. A higher FT4 level is potentially related to increased 30-day mortality.

References values and predictive factors for thyroid volume in pregnant women.

Objective: Thyroid volume varies within each population according to different clinical and biochemical factors and can change during pregnancy. The present investigation was aimed to determine the reference values for thyroid volume in pregnant women and their predictive factors. Materials and methods: A cross-sectional study was carried out with 360 healthy pregnant women. The following variables were examined: maternal age, gestational age, skin color, current smoking status, parity, use of iodinated supplements, body mass index, thyrotropin, total and free thyroid hormones, thyroglobulin, antithyroid antibodies, chorionic gonadotropin, cholesterol and triglycerides. Results: The mean thyroid volume was 5.3 ± 1.3 mL, 5.4 ± 1.6 mL and 5.6 ± 2.5 mL in the first trimester, second trimester and third trimester, respectively. The reference interval was 2.47-9.49 mL in the first trimester, 3.17-9.01 mL in the second trimester, and 3.00-12.38 mL in the third trimester. Free triiodothyronine and triglycerides were predictors of thyroid volume (corrected R2 = 0.12; p = 0.000). Conclusion: This study is the first to determine the reference values for thyroid volume and its predictive factors in pregnant women from Cuba, a Caribbean island with sustainable elimination of iodine deficiency disorders.

Biotin induced biochemical hyperthyroidism: a case report and review of the literature.

BACKGROUND: Biotin is a commonly used supplement for hair, nail, and skin. Recent literature suggests that high-dose biotin therapy for neurological diseases like Multiple sclerosis can interfere with lab results that use biotin/streptavidin immunoassay, called biotin interference. Biotin interference can affect thyroid lab results, giving biochemical hyperthyroidism. CASE PRESENTATION: Our patient, a 64-year-old white man with a known history of multiple sclerosis, presented with elevated free T3, free T4, and low TSH that resembled hyperthyroidism. He had no symptoms of hyperthyroidism except some fatigue and tachycardia on the first encounter. He was started on anti-thyroid medications. He was then re-evaluated since his lab results remained the same after two months of anti-thyroid medications. It was found that he was on biotin, 10000mcg/day, for his multiple sclerosis. Biotin was discontinued, and five days later his lab results returned to normal values. CONCLUSION: The lack of knowledge of biotin use by patients can lead to misdiagnosis of patients' thyroid lab results and improper management. Awareness about biotin interference and abnormal thyroid lab values should be a priority among clinicians and the public. If the biotin is discontinued on time, such misdiagnosis can be avoided.

Significant Interference of Biotin in Thyroid Function Tests Using Beckman Analyzer: How to Identify such Interferences?

OBJECTIVE: Biotin in elevated concentration interferes with biotin-based immunoassays. We studied biotin interferences in TSH, FT4, FT3, total T4, total T3 and thyroglobulin assays both in vitro and in vivo using Beckman DXI800 analyzer. METHODS: Two serum pools were prepared from left-over specimens. Then aliquots of each pool (and serum control) were supplemented with various amounts of biotin followed by measuring thyroid function tests again. Three volunteers each took 10 mg biotin supplement. We compared thyroid function tests before and 2 h after taking biotin. RESULTS: We observed significant biotin interferences in biotin-based assays (positive interference with FT4, FT3, and total T3 assay but negative interference with thyroglobulin) both in vitro and in vivo but non-biotin-based assays (TSH and total T4) were not affected. CONCLUSIONS: Elevated FT3 and FT4 in the presence of normal TSH is inconsistent with hyperthyroidism and should be followed up with total T3 and T4 test. Significant discrepancy between total T3 (falsely elevated value due to biotin) and total T4 (not affected as the assay is not biotin based) maybe an indication of biotin interference.

The impact of vitamin D deficiency on some biochemical parameters and clinical outcome in Palestinian pregnant women during the first trimester.

BACKGROUND AND AIM: Vitamin D deficiency is widespread worldwide and associated with negative effects on maternal and neonatal health. This study aimed to evaluate the relationship between vitamin D and thyroid and parathyroid hormone levels in the first trimester of pregnancy. MATERIAL AND METHODS: This case control study included 200 participants aged (18-40) years divided into two groups; 100 pregnant females at the first trimester as case group, attending the main general clinical centers in Gaza strip, Palestine and 100 apparently healthy non-pregnant females as control group. Vitamin D, free thyroxine, free triiodothyronine, thyroid stimulating hormone, parathyroid, and the autoantibodies specific for thyroglobulin and thyroid peroxidase in serum were measured in all mothers and statistically analyzed using SPSS version 21 software. RESULTS: Serum vitamin D, TSH, anti-TPO, and anti-TG levels were significantly decrease while, parathyroid levels were non-significantly decreased in the first trimester of pregnancy compered to control group. The levels of fT4 were significantly increased and level of fT3 were non significantly increased among pregnant mothers compered to control group. Analyses using Pearson correlation coefficients showed positive correlations between vitamin D with fT4, fT3, Anti-TPO with P -value < 0.05 and negative correlations with mother age, TSH, PTH with P-value < 0.05 in early pregnancy. CONCLUSIONS: Vitamin D deficiency among pregnant women in the first-trimester can be associated with thyroid, parathyroid parameters and thyroid autoantibodies with potential adverse consequences for overall health, emphasizing a routine monitoring and vitamin D supplementation prevention strategies to optimize maternal and fetal outcomes.

How to manage Graves' disease in women of childbearing potential.

The management of Graves' disease (GD) in women of childbearing potential has multiple specific complexities. Many factors are involved, which differ at the various stages from preconception, conception, first trimester, later pregnancy, postpartum and lactation, with both maternal and foetal considerations. The incidence and significance of the risks incurred from antithyroid drugs (ATDs) in pregnancy have been re-evaluated recently and must be balanced against the risks of uncontrolled hyperthyroidism during childbearing years. Contraception is advised until hyperthyroidism is controlled. ATD cessation should be considered in those who are well controlled on low dose therapy before conception and in early pregnancy. Advice on iodine supplementation does not generally differ in those with GD. Radioiodine (RAI) is contraindicated from 6 months preconception until completion of breastfeeding. In all women who have a history of GD, monitoring of TSH receptor antibodies (TRAb) is strongly recommended during pregnancy, and if elevated, foetal monitoring and assessment of thyroid function in the neonate are required. Of note, RAI increases TRAb for up to a year, making this treatment option even less attractive in this patient group. A small amount of ATD is transferred into breast milk but low doses are safe during lactation. Routine periodic thyroid function testing is recommended in remission to detect postpartum GD recurrence. We present our approach to the Clinical Question 'How to manage GD in women of childbearing potential?'

Thyroid function tests of iodine deficiency goiter can mimic thyroid hormone resistance alpha.

OBJECTIVES: Iodine deficiency goiter can develop in children on a restrictive diet and most have normal thyroid function. We report a 6-year-old girl with iodine deficiency goiter with thyroid function studies mimicking thyroid hormone resistance alpha. Thyroid hormones mediate its effects through thyroid hormone receptors alpha and beta. Biochemical picture of low/low-normal T4 and high/high-normal T3 levels, variably reduced reverse T3 and normal TSH is characteristic of thyroid hormone resistance alpha. CASE PRESENTATION: A 6-year-old girl, born out of non-consanguineous marriage presented with goiter of 1.5 years duration. She was without symptoms of thyroid dysfunction. The patient was evaluated at one year of age for macrocephaly with cranial ultrasound which was normal. She had normal growth and development. Patient was vegan and was not on any medications or supplements. Laboratory work up showed TSH 5.03 uIU/mL (0.34-5.5), FT4 0.3 ng/dL (0.58-1.2), FT3 5.3 pg/mL (2.5-3.9), total T3 258 ng/dL (94-241), reverse T3 <5.0 ng/dL (8.3-22.9) and negative thyroglobulin antibody and thyroid peroxidase antibody. Thyroglobulin level was 1,098.8 ng/mL (<13 ug/L), and urine iodine 15.8 ug/L (<100 ug/L) confirming a diagnosis of iodine deficiency goiter. Patient was started on iodine supplements, 150 ug daily and repeat work up 3 months later were TSH: 2.717 uIU/mL, T3, total 182 ng/dL, T4, total 9.3 ug/dL, FT 4 2.1 ng/dL. CONCLUSIONS: Iodine deficiency goiter may present with low FT 4, elevated T3 and normal TSH mimicking thyroid hormone resistance alpha and should be considered in children on restrictive diet.

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.

Efficacy of subcutaneous Levothyroxine in a case of refractory hypothyroidism: A case report.

RATIONALE: Daily oral synthetic levothyroxine (LT4) is the main treatment for hypothyroidism, which, in most cases, allows the regression of symptoms and the normalization of the thyroid function. However, rarely, despite a high dose of oral LT4, hypothyroidism persists and is called refractory hypothyroidism. Intravenous or intramuscular treatment is then often necessary. We report the case of a patient with refractory hypothyroidism successfully treated with subcutaneous LT4. INTERVENTIONS AND OUTCOMES: After 4 weeks of weekly intravenous injections of 200 µg LT4 in complement to the oral treatment, thyroid balance was improved (TSH: 21.8 mIU/L). We tested the replacement of intravenous with subcutaneous injections of LT4 and gradually increased injection frequency from 1 to 3 injections per week (600 µg/week). Simultaneously, oral treatment was gradually tapered off, and within a few months, thyroid function tests were normalized. Two years later, hormone levels remained normal without symptoms of hypothyroidism. The only side effect was a local reaction in the first few weeks of injections, which spontaneously resolved. LESSONS: In this case of unexplained oral LT4 malabsorption, subcutaneous injection allowed a self-administrated physiological dose of LT4 3 times weekly. Considering the efficacy of subcutaneous injection of LT4, this treatment could be a safe and easy alternative for patients with malabsorption.

Postnatal Serum Total Thyroxine Level Associated with Short- and Long-Term Anthropometric Outcomes in Very Preterm Infants.

Thyroxine (T4) importantly regulates the growth of newborns. Compared to fetuses with equivalent gestational ages, very preterm infants (VPIs) often experience relatively low thyroxinemia, with a normal thyroid-stimulating hormone (TSH) concentration < 10 µIU/mL. However, there is continued debate regarding postnatal thyroxine supplementation for VPIs with normal TSH and transitionally low thyroxinemia. Little research has explored the role of the postnatal total T4 (TT4) serum concentration on the growth of VPIs. In this study, we aim to clarify whether the postnatal thyroxine concentration is associated with the short- and long-term growth outcomes of VPIs. A total of 334 surviving VPIs in our previously reported cohort, born in the period August 2007−July 2016, were enrolled. The exposure variable was the postnatal TT4 concentration at 1 month old. The primary outcomes were body weight increments over 28 days after the screening and anthropometric outcomes at the corrected age of 24 months old. Infants with any hormonal replacement, severe brain injury, congenital anomaly, or cerebral palsy were excluded. In total, 290 (86.8%) VPIs were included for analysis. In the 28 days after thyroid function screening, the TT4 concentration was found to have a significant association with positive increments in body weight (mean increment: 25.7 g per 1 µg/dL; p < 0.001) and a positive body weight z-score (mean increment: 0.039 per 1 µg/dL; p = 0.037), determined by generalized estimating equation analysis. At the corrected age of 24 months old, a higher postnatal TT4 concentration was associated with a lower body mass index (mean coefficient: −0.136; 95% CI: −0.231 to −0.041, p = 0.005) and lower body mass index z-score (mean coefficient: −0.097; 95% CI: −0.170 to −0.024, p = 0.009). Infants with a TT4 concentration > 6.4 ug/dL had significantly lower odds of overweight status (odds ratio: 0.365; 95% CI: 0.177 to 0.754, p = 0.006). We conclude that the postnatal TT4 concentration is associated with a positive increment in body weight in the short term. At the same time, the postnatal TT4 concentration is associated with lower odds of overweight status after long-term follow-up.

Thyroid and Parathyroid Conditions: Hypothyroidism.

Hypothyroidism is caused by deficient thyroid hormone production secondary to autoimmune disease or insufficient iodine consumption or as a complication of hyperthyroidism management. Signs and symptoms include fatigue, weight gain, dry skin, constipation, and cold intolerance. The U.S. Preventive Services Task Force found insufficient evidence to recommend for or against screening for hypothyroidism, but some organizations support screening in special populations. If hypothyroidism is suspected, initial laboratory evaluation consists of a serum thyrotropin (TSH) measurement with reflex testing of free thyroxine (T4). Thyroid function tests must be interpreted carefully because acute illness, diet, and drugs may alter values. Overt hypothyroidism occurs when a patient has an elevated TSH level and a low free T4 level with symptoms of hypothyroidism. Management includes thyroid hormone replacement, ideally levothyroxine. Subclinical hypothyroidism is characterized by an elevated TSH level with a normal T4 value. The decision to treat subclinical hypothyroidism should be based on patient characteristics and shared decision-making discussions. Special consideration should be taken in treating patients with high-risk conditions, including heart disease, pregnancy, and myxedema coma, and in patients requiring high-dose levothyroxine. Thyroid hormone should be titrated based on goal TSH values, symptoms, and potential treatment adverse effects.

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.

Dubiously increased FT4 and FT3 levels in clinically euthyroid patients: clinical finding or analytical pitfall?

OBJECTIVES: We systematically investigated normally or subclinically increased thyroid stimulating hormone (TSH) values associated with unexpectedly increased thyroxine (FT4) and free triiodothyronine (FT3) in findings of patients without any thyroid disease. Moreover, we looked for alternatives to overcome such states with an improved diagnostic procedure and to investigate the pathogenetic background of the respective patients. METHODS: Samples with TSH concentrations within the range of 0.4-10 mU/L combined with increased concentrations of FT4 (n=120; Cobas, Roche) were collected over a period of around six years. Cobas FT4 results were compared with measurements from Liaison (DiaSorin) and Architect (Abbott) FT4 assays. For further validation all samples were measured for total thyroxine (TT4) (Cobas, Roche). Finally, FT3 and TT3 as complementary parameters were measured in samples with leftover material. To overcome potential analytical disturbances from stimulating heterophilic antibodies, we used heterophilic blocking tubes (HBTs). RESULTS: From the 120 samples with increased FT4 concentrations by Cobas, 51/120 were also increased by Liaison, and 26/120 by Architect. However, the measurement of TT4 indicated only n=10/120 increased values. The number of increased FT3 (n=71) measurements was higher in Architect>Cobas>Liaison (28>27>9). TT3 levels of 70/71 samples were within the reference interval. HBTs were inappropriate to reduce unspecific immunoreactivity in our samples. No clear pathogenetic background could be elucidated in the anamnesis of individual patients. CONCLUSIONS: To overcome dubious constellations of TSH, FT4, and FT3, it is helpful to measure TT4 and TT3 for control or to use an immunoassay with an alternative assay design for the respective parameters.