Serum Thyroid Hormone Concentrations Research Articles

Exposure to Multiple Per- and Polyfluoroalkyl Substances In Relation To Thyroid Function Among Adolescents and Young Adults from NHANES 2011-2012

BACKGROUND AND AIM: Per- and polyfluoroalkyl substances (PFASs) are persistent chemicals with a wide range of industrial applications, measured in human serum samples. Experimental studies have identified PFASs as endocrine disrupting chemicals and epidemiological studies suggest that PFASs can affect normal thyroid function in humans. We investigated the association between exposure to mixtures of serum PFASs and changes in serum thyroid hormone levels among 12 to 20 year olds. METHODS: Using data from the NHANES 2011-2012 cycle, we employed principal component analysis (PCA) and identified three factors, describing mixtures of PFASs. Using multivariable linear regression models, we estimated associations between exposure to PFAS mixtures and changes in serum thyroid hormone concentrations. RESULTS:Factor 1 was characterized by carboxylates, comprising of PFUnA, PFDA, and PFNA, Factor 2 was described by sulfonates which included PFHxS, PFOS, PFA, and MeFOSAA and Factor 3 was described PFHpA alone. Greater exposure to Factor 1 PFASs was associated with an overall increase in free T4, TSH, and thyroid peroxidase antibodies levels, without any statistical significance. Exposure to Factor 2 PFASs was associated with an overall decrease in free T3, total T3, free T4, and total T4 levels. Factor 3 resulted in an increase in most of the serum thyroid hormone levels with the exception of thyroglobulin and thyroglobulin antibodies levels. CONCLUSIONS:Our results suggest the importance of modeling the effects of exposure to a mixture of PFASs simultaneously. The findings of this analysis can better inform researchers and policy makes on which PFASs behave analogously or inversely in an effort to better assess the effect PFASs may have on health effects. KEYWORDS: biomarkers, chemical mixtures, endocrine disruptors, polyfluoroalkyl substances, thyroid function

Associations between the thyroid panel and serum protein concentrations across pregnancy

Establishing any characteristic associations between the serum parameters of thyroid function and serum proteins in pregnancy may aid in elucidating the role of the thyroid gland in the regulation of pregnancy-specific metabolic processes and in selecting candidate biomarkers for use in their clinical assessment. Concentrations of thyroid stimulating hormone (TSH), free tri-iodothyronine (fT3) and free thyroxine (fT4), six electrophoretically separated protein fractions (albumin, alpha-1-, alpha2-, beta-1-, beta-2- and gamma-globulins), representative proteins—albumin (ALB), transferrin (TRF), alpha-2-macroglobulin (AMG) and ceruloplasmin (CER) were measured in 136 serum samples from 65 women in their consecutive trimesters of pregnancy. The concentrations of TSH, fT4 and fT3 were significantly correlated (p < 0.05) with the concentrations of the albumin, alpha-2- and beta-1 globulin fractions. Significant correlations (p < 0.05) which were positive between fT4 and ALB and negative between fT4 and TRF were established throughout pregnancy. Significant negative correlations (p < 0.05) were demonstrated for fT3 with alpha-2-globulin, AMG and CER. Changes in the serum concentrations of thyroid hormones seen between the trimesters were found to correlate with the concentrations of high-abundance serum proteins. Opposite directions of correlations between fT4 and ALB and fT4 and TRF observed throughout pregnancy may indicate the shared biological role of these parameters in maintaining maternal homeostasis and they suggest their potential use in the clinic as a simple biomarker panel. A negative correlation of fT3 with CER in the second trimester possibly reflects their involvement in the active regulation of metabolic processes.

LONG-TERM FOOD RESTRICTION AND DIABECON ADMINISTRATION AMELIORATES ALLOXAN-INDUCED HYPERGLYCEMIA, THYROID DYSFUNCTION, AND OXIDATIVE STRESS IN RAT.

Objective: The comparative effects of food restriction (FR), Diabecon treatment (DT) and their combined therapy (FR+DT) were studied in the regulation of alloxan-induced diabetes mellitus, alterations in thyroid hormones (TH) and oxidative stress.&#x0D; Methods: Young diabetic rats were either kept on 50% FR and/or DT (2 gm/Kg body weight) for two months and then alterations in serum glucose, insulin, TH concentrations, hepatic glycogen and pancreatic antioxidants along with oxidative stress markers were evaluated.&#x0D; Results: Significantly increased serum glucose, tissue stress markers with decreased TH, hepatic glycogen (P&lt;0.0001 for all) and pancreatic antioxidants (P&lt;0.05-0.001) were observed in diabetic rats. Rats kept on different therapies exhibited significant (P&lt;0.05) improvements than diabetic rats in all studied parameters. FR+DT group showed a significantly more decrease in serum glucose (P&lt;0.05) that FR or DT group, while in other parameters improvement was found to be more or less equally improved in all treated groups.&#x0D; Conclusion: FR appeared to mimic the effects of Diabecon in most of the indices. However, FR+DT appears to be more effective. Possibly both therapies ameliorate diabetes and oxidative stress following some common metabolic pathways.

Effects of Daily Kelp (Laminaria japonica) Intake on Body Composition, Serum Lipid Levels, and Thyroid Hormone Levels in Healthy Japanese Adults: A Randomized, Double-Blind Study.

To investigate whether supplementation with iodine-reduced kelp (Laminaria japonica) powder decreases body fat composition in overweight Japanese subjects, a randomized, double-blind, placebo-controlled intervention study was conducted in 50 Japanese subjects with body mass index (BMI) ≥25 and <30 kg/m2. Subjects were randomly assigned to consume thirty tablets/d (10 tablets orally, 3 times/d) containing either iodine-reduced kelp powder (test, 6 g kelp powder corresponding to 3 g alginate/d) or kelp-free powder (placebo) for 8 weeks. Anthropometric measurements, blood lipids, and serum thyroid hormone levels were obtained before and after the trial. Body fat percentage was significantly decreased in male subjects from the test group compared with the placebo group. The same tendency was observed for body weight (p = 0.065) and BMI (p = 0.072) in male subjects. No significant changes in anthropometric measurements or visceral fat area were observed in female subjects. Serum thyroid hormone concentrations did not increase after 1.03 mg/d of iodine supplementation through kelp intake. The intake of iodine-reduced kelp powder led to significant and safe reductions in body fat percentage in overweight male subjects. The consumption of kelp high in alginate may contribute to preventing obesity without influencing thyroid function in Japanese subjects with a relatively high intake of iodine from seaweed.

Environmental arsenic exposure and its toxicological effect on thyroid function: a systematic review.

This study was performed to review epidemiological evidence related to Arsenic (As) effects on the thyroid function by focusing on the serum thyroid hormone concentration. As, one of the main pollutants, has been recognized as an endocrine-disrupting agent that may affect the function of thyroid as shown by experimental studies. This systematic study indicates the association between As exposure and thyroid dysfunction. The studies have shown an association between serum and urine concentration of arsenic and thyroid dysfunction. Most of them reported the association between increase in the serum or urine As levels and decrease in the triiodothyronine (T3) and thyroxine (T4), and also elevation in the thyrotropic hormone (TSH) levels. Our findings related to the effects of As on the function of thyroid in humans are still limited and future studies should be done to address this question.

Successful Management of Hyperthyroidism With Lithium and Radioiodine in a Patient With Previous Methimazole-Induced Agranulocytosis

Introduction: Antithyroid drug (ATD) therapy is the first-line treatment of Graves’ hyperthyroidism. Agranulocytosis, although rare, is a life-threatening condition associated with ATD therapy. For patients who recovered from ATD-induced agranulocytosis, surgery or radioiodine (RAI) therapy are adequate options to restore the patient’s euthyroid state. Here we report a case of ATD-related agranulocytosis where lithium therapy was used before RAI to control thyrotoxicosis and prevent worsening of hyperthyroidism. Case Report: A 74-year-old female with a previous history of hypertension presented with a 2-month history of weight loss (12 lbs), palpitations and shortness of breath. She was afebrile with a heart rate of 110, a blood pressure of 149/80, a fine tremor and a moderate diffuse goiter. She had a normal eye exam. Laboratory evaluation demonstrated TSH <0.01 uIU/mL (0.35-5.5), FT4 3.11 ng/dL (0.51-1.65) and TSH receptor antibody (TRAb) 40 (<1,0 U/L), consistent with thyrotoxicosis due to Graves’ disease. She was started on methimazole (MMI) 15mg and metoprolol. After four weeks, symptoms resolved and thyroid function tests (TFT) improved. However, after two months of treatment, she was hospitalized for fever, diarrhea and abdominal pain. White blood cell count (WBC) was 650/μL, and neutrophil count was 90/μL. A diagnosis of gastroenteritis and agranulocytosis was made and MMI was stopped. After seven days, symptoms resolved, the neutrophil count was 2200/ul and TFT were acceptable (FT4 1.25, ng/dL TT3 1.67 ng/ml, TSH < 0.02 uIU/mL). She was discharged without ATDs and a RAI dose of 20 mCi was scheduled. However, RAI therapy had to be postponed due to COVID-19 pandemic restrictions. After 3 weeks, TFT worsened and therapy with lithium carbonate 300 mg TID was started as the patient refused thyroidectomy. Lithium was initiated 12 days before RAI therapy and was maintained 7 days after the procedure. No side effects associated with lithium treatment were reported. TFT 7 days after RAI were FT4 1.43, ng/dL TT3 2.05 ng/ml and TSH < 0.02 uIU/mL. One month later, the patient was euthyroid without need for thyroid medication and remains on follow up. Discussion: Serum thyroid hormone (TH) concentrations usually increase after RAI therapy for Graves’ disease, a worrisome fact in patients with increased risk for cardiovascular complications. Previous studies report that pre-RAI treatment with lithium prevents changes in serum TH concentrations and enhances RAI therapy’s effectiveness. Here, treatment with lithium was used to control thyrotoxicosis and prevent further increase in TH levels associated with RAI therapy. Lithium is particularly suitable for patients with ATD-related side effects before definitive therapy (radioiodine or thyroidectomy). The antithyroid effect of lithium in this setting should be further studied.

Selenium source and level on performance, selenium retention and biochemical responses of young broiler chicks

BackgroundSelenium (Se) has been recognized as an essential micronutrient for nearly all forms of life. In recent decades, broiler responses to dietary Se supplemental levels and sources have received considerable attention. On environmental grounds, organic trace mineral utilization in practical broiler feeds has been defended due to its higher bioavailability. In such feeds, trace minerals are provided simultaneously in the same supplement as inorganic salts or organic chelates, a fact commonly ignored in assays conducted to validate organic trace mineral sources. The current assay aimed to investigate growth and biochemical responses, as well as Se retention of growing chicks fed diets supplemented with organic and inorganic Se levels and where the trace minerals (zinc, copper, manganese, and iron) were provided as organic chelates or inorganic salts according to Se source assessed. In so doing, a 2 × 5 factorial arrangement was used to investigate the effects of sodium selenite (SS) and selenium-yeast (SY) supplemented in feeds to provide the levels of 0, 0.08, 0.16, 0.24, and 0.32 mg Se/kg.ResultsChicks fed selenium-yeast diets had body weight (BW), and average daily gain (ADG) maximized at 0.133 and 0.130 mg Se/kg, respectively. Both Se sources linearly increased (P < 0.05) the glutathione peroxidase (GSH-Px) activity in chick blood but higher values were observed in sodium selenite fed chicks (P < 0.05). Both Se sources influenced thyroid hormone serum concentrations (P < 0.05). Chicks fed SY exhibited greater retention of Se in the feathers (P < 0.05). Relative bioavailability of selenium yeast compared with SS for the Se content in carcass, feathers, total and Se retention were, 126, 116, 125 and 125%, respectively. SY supplementation resulted in lower liver Se concentration as Se supplementation increased (P < 0.05).ConclusionsBased on performance traits, the supplemental level of organic Se as SY in organic trace minerals supplement to support the maximal growth of broiler chicks is 0.133 mg Se/kg.

The Iodine Status and Prevalence of Thyroid Disorders Among Women of Childbearing Age in China: National Cross-sectional Study

ObjectiveMandatory universal salt iodization in China was implemented 20 years ago. However, the current iodine status and prevalence of thyroid disorders among childbearing-age women are unknown. MethodsA nationally representative cross-sectional study with 26 166 enrolled participants aged 18 to 49 years from all 31 provincial regions of mainland China was performed. The participants were given a questionnaire and underwent B-mode ultrasonography of the thyroid. The serum concentrations of thyroid hormones and thyroid antibodies and the urinary iodine concentration (UIC) were measured. ResultsThe median UIC was 178.7 μg/L, indicative of adequate iodine status. pHowever, 19.04% and 19.87% of the participants were classified as having iodine deficiency and excessive iodine, respectively. The weighted prevalence of thyroid disorders was as follows: 1.08% had overt hyperthyroidism, 0.58% had subclinical hyperthyroidism, 0.76% had Graves disease, 1.28% had overt hypothyroidism, 14.28% had subclinical hypothyroidism, 13.53% were positive for thyroid peroxidase antibodies, and 14.55% were positive for thyroglobulin antibodies. Excessive iodine and overweight were associated with higher odds of subclinical hypothyroidism. A family history of thyroid disorders and an age between 40 and 49 years were significantly associated with higher odds of positivity for thyroid peroxidase antibodies and thyroglobulin antibodies. ConclusionIodine deficiency, excessive iodine, subclinical hypothyroidism, and positivity for thyroid autoantibodies remain prevalent among women of childbearing age in China. Women of childbearing age who are relatively older, are overweight, or have a family history of thyroid disorders are encouraged to undergo active screening of their UIC and thyroid function when planning a pregnancy.

Progesterone supplementation in Holstein heifers subjected to cooling and timed AI during summer: physiological and reproductive variables and thyroid hormone concentrations.

Our aim was to evaluate the effects of progesterone supplementation after fixed-time artificial insemination (FTAI) on physiological and reproductive variables and serum thyroid hormone concentrations of cooled Holstein heifers during a hot summer season. Sixty-nine Holstein heifers were randomly assigned to three treatments: (1) heifers under visual estrus detection and inseminated according to AM-PM rule (n = 23; control (C)), (2) heifers subjected to FTAI after estrus synchronization using a CIDR insert (n = 24; FTAI group), and (3) heifers treated as the FTAI group plus progesterone supplementation between the day 4 and 14 post-insemination with a reused CIDR device (n = 22; FTAI+SP4 group). All heifers were cooled daily with misting and fans. Physiological variables were measured; likewise, blood samples were collected to determine serum progesterone, thyroxine, and triiodothyronine concentrations. Both respiration rate and rectal temperature were similar among treatments. Conception rate was greater (P < 0.05) in C (65.2%) and FTAI+SP4 (59.1%) heifers than in FTAI heifers (33.3%). Serum triiodothyronine and progesterone concentrations of FTAI+SP4 heifers were similar to those of C heifers but greater (P < 0.05) than those of FTAI heifers. In conclusion, progesterone supplementation post-insemination increased conception rate and serum progesterone concentrations without affecting thermoregulation capacity in Holstein heifers subjected to FTAI and cooling during a hot summer season.

Growth performance and changes in physiological, metabolic and hematological parameters due to outdoor heat stress in hair breed male lambs finished in feedlot.

The aim of this study was to evaluate the effect of seasonal heat stress (HS) on productive performance, physiological responses, metabolism, and hematological profile of hair breed male lambs finished in feedlot. Twenty Dorper × Katahdin male lambs (body weight = 34.6 ± 1.4 kg and age = 4.5 months) were housed in individual pens and exposed to environmental conditions of summer HS (n = 10, temperature = 28.3 ± 4.0 °C and THI = 77.2 ± 5.4 units) or winter thermoneutrality (n = 10, temperature = 19.2 ± 2.6 °C and THI = 64.0 ± 3.0 units). Each season, a 30-day feeding test was conducted to measure study variables. Compared to thermoneutral lambs, heat-stressed lambs had lower (P < 0.01) growth rate and feed efficiency without changing dry matter intake. Heat-stressed lambs presented higher (P < 0.01) rectal temperature and respiratory rate through the daytime than termoneutral lambs. On most sampling days, summer HS caused lower (P < 0.01) serum concentrations of glucose, cholesterol, total protein, urea, potassium, and thyroid hormones, but higher (P < 0.01) serum triglyceride and chlorine values. Overall serum concentrations of cortisol and insulin were unaffected by summer HS. The blood of heat-stressed lambs showed lower (P ≤ 0.03) erythrocyte and platelet counts, hemoglobin, and hematocrit, but higher (P ≤ 0.03) erythrocyte size and leucocyte count than the blood of thermoneutral lambs. In conclusion, hair breed male lambs in response to chronic conditions of summer HS had slow growth but avoided hyperthermia due to the activation of physiological, metabolic and endocrine adjustments.

Serum tT4, fT4 and TSH concentrations in German Shepherd dogs depending on age and type of work.

Serum concentration of thyroid hormones in healthy dogs varies according to age, sex, breed or professional activity. The aim of this study was to determine the influence of both age and dogs' work involvement on TSH and thyroid hormones values. Thyroid-stimulating hormone (TSH), total thyroxine (tT4) and free thyroxine (fT4) were tested in the serum of 57 healthy, German Shepherd dogs. The dogs were divided into study groups according to age: dogs aged 3 to 6 years (A), dogs over the age of 6 years (B) and involvement: police-working dogs (C) and accompanying animals (D). Mean values of TSH, tT4 and fT4 ranged from 0.19 to 0.31 ng/ml, 15.58 to 17.25 nmol/L and 11.83 to 17.89 pmol/L, respectively. The highest values of TSH were in group B and the lowest were in group A, while there was an inverse dependence in case of fT4 concentration. The highest mean values of tT4 were in dogs in group C and the lowest in group B. There were statistically significant differences in TSH (p=0.007) and fT4 (p=0.003) concentrations between the age groups. The results indicate that a dog's age is an important factor in the case of thyroid profile results interpretation.

Thyroid panel reference intervals in healthy children and adolescents: A Spanish cohort

ObjectivesIn children, thyroid hormones are essential for correct physical and neurological development. The recommended process for defining reference intervals (RIs) is the direct approach; however, indirect methods are an effective alternative. This study aimed to explore age- and sex-dependent relationships between serum concentrations of thyroid hormones in a large population-based cohort of healthy Spanish Caucasian children and calculate RIs. Material and MethodsResults of serum thyroid-stimulating hormone (TSH) and free thyroxine (fT4) were collected from laboratory data of N (TSH = 23201; fT4 = 20728) patients aged 1 month − 15 years. These results were validated with a prospective study.Analyses of serum concentrations of TSH and fT4 were performed on ARCHITECT i2000 (Abbott Diagnostics, US). Percentiles (2.5th to 97.5th) were determined for each variable and taken as the RI. ResultsNo difference was found between serum TSH concentrations in male and female children of all age groups. A difference between serum fT4 concentrations in males and females and an age-dependent correlation for both sexes were found. ConclusionThere is very little consensus on RIs in children. Our data confirm it is possible to use data mining techniques to calculate reliable and clinically useful RIs.

Estimated change in prevalence of abnormal thyroid-stimulating hormone levels in China according to the application of the kit-recommended or NACB standard reference interval.

BackgroundBoth the kit-recommended and United States National Academy of Clinical Biochemistry (NACB) standard thyroid-stimulating hormone (TSH) reference intervals (RIs) are used to determine thyroid dysfunction in clinical practice and epidemiological surveys in China. However, a number of kit-recommended RIs were derived from the European or United States reference population.MethodsA nationally representative cross-sectional study with 78,470 enrolled participants aged 18 years or older from China was performed. Serum concentrations of thyroid hormones, TSH, thyroid antibodies (by Roche Diagnostics), and urine iodine concentration (UIC) were measured.FindingsThe abnormal TSH weighted prevalence was 15.33% (95% CI, 14.24% to 16.49%) according to the kit-recommended RI and 6.89% (6.46% to 7.34%) according to the NACB standard RI. The NACB standard prevalence of abnormal TSH was associated with an absolute change in abnormal TSH prevalence of −11.20% (−12.23% to −10.18%) among women. When estimating the proportion of supranormal TSH levels according to background characteristics, the NACB standard definition decreased the prevalence by more than 10% in some categories, with the highest absolute difference of −13.92% (−15.52% to −12.33%) observed among the elderly, −12.85% (−13.68% to −12.02%) among those with UIC ≥300 μg/L, and −12.15% (−13.02% to −11.28%) among non-smokers. For subnormal TSH, with the highest absolute difference of 3.17% (2.74% to 3.61%) observed among regular smokers, 3.11% (2.49% to 3.74%) among the elderly, and 2.53% (2.29% to 2.77%) among those with BMI <25.InterpretationFor adults in China, the NACB standard RI of TSH reveals a lower estimated prevalence of supranormal TSH levels than the kit-recommended RI. Because of the public health significance of overt and subclinical hypothyroidism and the very large population base in China, the TSH RI should be further assessed.FundingNational Health Commission of the People's Republic of China and National Natural Science Foundation of China.

High Prevalences of Subclinical Hypothyroidism and Positive Thyroid Autoantibodies Recorded Among Women of Childbearing Age in China: National Cross-Sectional Study

Background: Iodine deficiency and thyroid disorders are associated with several obstetric and neonatal adverse outcomes. Mandatory universal salt iodization in China was implemented 20 years ago; however, the current iodine status and prevalence of thyroid disorders among women of childbearing age are unknown. Methods: A nationally representative cross-sectional study with 26166 enrolled participants aged 18 to 49 years from all 31 provincial regions of mainland China was performed. The participants were given a questionnaire and underwent B-mode ultrasonography of the thyroid. The serum concentrations of thyroid hormones and thyroid antibodies and the urine iodine concentration (UIC) were measured. Findings: The median UIC was 178.7 μg/L, which is indicative of adequate iodine status; however, 19.04% and 19.87% of the participants were classified as having iodine deficiency and excessive iodine, respectively. The weighted prevalences of thyroid disorders were as follows: 1.08% had overt hyperthyroidism, 0.58% had subclinical hyperthyroidism, 0.76% had Graves’ disease, 1.28% had overt hypothyroidism, 14.28% had subclinical hypothyroidism, 13.53% were positive for TPOAb, and 14.55% were positive for TgAb. Excessive iodine and overweight were associated with higher odds of subclinical hypothyroidism. A family history of thyroid disorders and an age between 40 and 49 years were significantly associated with higher odds of positivity for TPOAb and positive TgAb. At the provincial level, the prevalences of iodine deficiency, excessive iodine, subnormal TSH levels, and supranormal TSH levels varied widely. Gansu was identified as a region with high prevalences of both excessive iodine and supranormal TSH levels. Interpretation: Iodine deficiency, excessive iodine, subclinical hypothyroidism, and positivity for thyroid autoantibodies are still prevalent among women of childbearing age in China. Women of childbearing age who are relatively older, have excessive iodine, are overweight, or have a family history of thyroid disorders are encouraged to undergo active screening of their UIC and thyroid function when planning a pregnancy. Strategies for addressing iodine status and thyroid disorders require geographic targeting of this subpopulation. Funding Statement: National Health Commission of the People’s Republic of China and National Natural Science Foundation of China. Declaration of Interests: The authors declare no conflict of interests. Ethics Approval Statement: The research protocols were approved by the Medical Ethics Committee of China Medical University.

Organophosphate pesticide exposure, hormone levels, and interaction with PON1 polymorphisms in male adolescents

ObjectiveTo examine the association between urinary metabolites of organophosphate (OP) pesticides and serum concentrations of thyroid and reproductive hormones in male adolescents and to assess the potential effect of interactions between OP pesticides and paraoxonase 1 (PON1) polymorphisms on hormone levels. MethodsStudy subjects (N = 117) were male 16- to 17-year-olds from the Environment and Childhood (INMA)-Granada cohort in Spain. Concentrations of 3,5,6-trichloro-2-pyridinol (TCPy), a metabolite of chlorpyrifos/chlorpyrifos-methyl, 2-isopropyl-6-methyl-4-pyrimidinol (IMPy), a metabolite of diazinon, and diethylthiophosphate (DETP) and diethyldithiophosphate (DEDTP), non-specific metabolites of OP pesticides, were measured in a spot urine sample from each subject and adjusted for creatinine. Levels of reproductive hormones (total testosterone [TT], estradiol [E2], dehydroepiandrosterone sulfate [DHEAS], sex hormone binding globulin [SHBG], luteinizing hormone [LH], follicle stimulating hormone [FSH], anti-Müllerian hormone [AMH], insulin growth factor 1 [IGF-1], and prolactin), thyroid hormones (free thyroxine [FT4], total triiodothyronine [TT3], and thyroid stimulating hormone [TSH]), and PON1 Q192R and L55M polymorphisms were determined in blood drawn during the same clinical visit. ResultsMultiple linear regression models showed that detectable levels of TCPy were associated with an increase in DHEAS and decreases in E2, FSH, and AMH; detectable IMPy with increases in E2, DHEAS, FSH, AMH, and prolactin and decreases in SHBG and LH; and detectable DETP with marginally-significant increases in TT and TT3 and decreases in FSH, AMH, and prolactin. The effect of IMPy and DETP on DHEAS and TT levels, respectively, was higher in subjects that carried the PON1 55MM genotype, while the effect of TCPy, IMPy, and DETP on thyroid hormone levels was higher in PON1 192QR/RR or 55MM genotype carriers. ConclusionsIn male adolescents, non-occupational exposure to OP pesticides was associated with several changes in reproductive and thyroid hormone levels, and the magnitude of some associations was greater in adolescents genetically more susceptible to OP pesticide exposure who carry the PON1 55MM genotype.

Euthyroid Sick Syndrome and Changes in Thyroid Hormones in Dogs with Hemoparasitosis

Background: Hemoparasitoses are extremely important in the clinical routine because they affect a large number of dogs. In spite of the abundance of studies on this topic, hormonal alterations caused by infection with these agents are still poorly known. Therefore, the goal of this work was to assess the serum levels of thyroid hormones of dogs infected with Ehrlichia canis (E. canis) alone, and dogs infected with E. canis and Babesia canis vogeli (B. vogeli) and/or Anaplasma platys (A. platys) before and after treatment with doxycycline chlorohydrate. This study also aimed at checking for presence of euthyroid sick syndrome (ESS) in these animals.Materials, Methods &amp; Results: The concentrations of the thyroid hormones total triiodothyronine (TT3), total tetraiodothyronine (TT4), free tetraiodothyronine (FT4), and canine thyroid-stimulating hormone (cTSH) were assessed by chemiluminescence in 12 dogs. Nested polymerase chain reaction (nPCR) was used to confirm diagnoses. The dogs were divided into 2 groups: G1, which comprised animals infected by E. canis alone, and G2, which included animals simultaneously infected by E. canis and B. vogeli and/or A. platys. The serum concentrations of the thyroid hormones were measured at two time points: before (D1) and after (D2) the 28-day treatment with generic doxycycline chlorohydrate (DC) at a dose of 10 mg/kg SID. On D2, another nPCR was carried out to check the efficacy of the treatment. On D2, in both groups, all dogs became negative for E. canis; however, 8 animals remained infected or were reinfected by other hemoparasites. On D1, 4 dogs in G1 exhibited low TT3 in conjunction with low TT4; one of the dogs had increased TT3 alone, and another dog had an increased TT3 accompanied by decreased TT4. In G2, on D1, one dog exhibited high TT3 accompanied by a decreased concentration of TT4; 2 dogs had decreased TT4; 2 dogs had increased TT3; and one dog had both TT3 and TT4 decreased. On D2, with only one exception, the animals in G1 that became negative for all hemoparasites under study exhibited normal serum levels of TT3 and TT4. Three dogs in G1, which were reinfected on D2, sustained decreased TT4 serum concentrations. Whereas, in G1 on D2, only one dog remained with a reduced serum TT4 concentration.Discussion: DC was effective at eliminating infection by E. canis in all dogs on D2. Even though this drug was unable to prevent reinfection of the animals by other hemoparasites, and in spite of divergent results on its efficacy at eliminating babesiosis and anaplasmosis, a clinical improvement was observed in all patients. A decrease in the serum concentrations of thyroid hormones (ESS) may occur in dogs with severe non-thyroid related diseases. Different authors have demonstrated the presence of ESS in dogs with hemoparasitoses; however, this is the first study to provide evidence on the existence of this syndrome in dogs with hemoparasitoses in Brazil, including dogs simultaneously infected by E. canis and B. vogeli and/or A. platys.We observed a reduction in TT3 and/or TT4 in dogs infected by E. canis, B. vogeli, and A. platys. We believe these results may help assessment of prognosis and patient follow-up, as TT4 concentrations returned to normal levels in all dogs that became negative for all hemoparasites after treatment; and only one dog in G1 sustained increased TT3, albeit lower than observed on D1. In animals of G1 that were reinfected after treatment started, TT3 returned to normal, even though TT4 levels remained decreased. In sum, all dogs in G1 and G2 exhibited TT3 and/or TT4 concentrations outside of the reference value ranges on D1, which indicates that alterations in the levels of thyroid hormones were due to infection by the hemoparasites. The animals infected by E. canis alone or simultaneously infected by B. vogeli and/or A. platys exhibited ESS.

Endocrine disrupting chemicals and thyroid hormone action.

Thyroid hormones (predominantly thyroxine, T4, and triiodothyronine, T3) are essential for normal development and for adult physiology. There are several challenges, however, that make identifying chemicals that produce adverse effects by interfering with the thyroid system difficult. First, individual variability in serum concentrations of thyroid hormones represent only about 10% of the population reference range that is considered to be "normal." This means that populations studies evaluating the relationship between chemical exposure and serum thyroid hormones must be large enough to overcome this internal variance. In addition, we know that there are chemicals that do not produce changes in thyroid hormone levels, but nevertheless impact thyroid signaling in target tissues. A good example is that of polychlorinated biphenyls (PCBs). PCB exposure during development are clearly associated with cognitive deficits in humans. But PCB exposure isn't uniformly associated with a reduction in serum thyroid hormone in human populations despite mechanistic studies showing that PCBs reduce serum T4 in animals. In contrast, perchlorate is a chemical that inhibits iodide uptake, thereby reducing thyroid hormone synthesis and serum hormone levels. Human studies have been variable in identifying a relationship between thyroid hormone and perchlorate exposure, but studies also show that dietary iodine, cigarette smoking and other factors can modify this relationship. The conclusion is that identifying chemicals that interfere with thyroid hormone could depend on in vitro analysis of chemicals that interact with different proteins important for thyroid hormone to function properly.

The relationship between thyroid function tests and sleep quality: cross-sectional study.

IntroductionThe relationship between sleep and hormones have long been recognized. Studies indicated that sleep quality is one of the major modulatory effects on the endocrine system. In this study, we aimed to assess the serum concentration of thyroid hormones in individuals who suffered from low quality sleep.Material and MethodsBased on the Pittsburgh Sleep Quality Index and ISMA Stress questionnaire, we divided 83 participants into two groups. Forty-one individuals with low quality sleep group and 42 with good quality sleep group, all from the male students of a medical school in Tehran, Iran, participated in this descriptive and cross-sectional study. Then, serum levels of thyroid hormones including free T3, free T4, and TSH were assessed and compared between two groups.ResultsThere were a significant increase in serum levels of FT4 (p=0.01) and TSH (p=0.02). There were also meaningful correlations between sleep score and stress score (p=0.008) as well as stress score and FT4 (p=0.03) in the case group.ConclusionsThe current study showed that thyroid function tests (T4 and TSH) significantly rose in the poor sleep condition. We also found correlations between sleep score, stress score, and FT4 in the poor sleep condition group that suggest low sleep quality can affect thyroid hormones.

Associations between maternal thyroid function in pregnancy and child neurodevelopmental outcomes at 20 months in the Seychelles Child Development Study, Nutrition Cohort 2 (SCDS NC2).

Maternal thyroid hormones facilitate optimal foetal neurodevelopment; however, the exact role of the thyroid hormones on specific cognitive outcomes is unknown. The present study aimed to investigate associations between maternal thyroid function and neurodevelopmental outcomes in the Seychelles Child Development Study (SCDS) Nutrition 2 cohort (n 1328). Maternal free thyroid hormones (fT3, fT4 and fTSH) were assessed at 28 weeks' gestation with a range of child cognitive outcomes analysed at 20 months. Dietary iodine intake was analysed for a subset of women through a Food Frequency Questionnaire. Linear regression analysis was used to test associations between serum concentrations of maternal thyroid hormones and child neurodevelopment outcomes. Thyroid hormones were analysed as continuous data and categorised as quintiles. 95% of mothers had optimal thyroid function based on fTSH concentrations. Overall, the present study shows that maternal thyroid function is not associated with neurodevelopmental outcomes in this high fish-eating population. However, a positive association, using quintiles for fT3, was reported for the Mental Developmental Index, between Q3 v. Q4 (β 0⋅073; P 0⋅043) and for Q3 v. Q5 (β value 0⋅086; P 0⋅018). To conclude, mothers in our cohort, who largely have optimal thyroid function and iodine intakes, appear able to regulate thyroid function throughout pregnancy to meet neurodevelopmental needs. However, it is possible that minor imbalances of fT3, as indicated from our secondary analysis, may impact offspring neurodevelopment. Further investigation of the relationship between maternal thyroid function and infant neurodevelopment is warranted, particularly in populations with different dietary patterns and thereby iodine intakes.

Effects of photoperiod on thyroid gland development and function in growing chicks: a biochemical and morphometric study

Context Light treatment has a regulatory role in some growth-related functions, including thyroid development in chicks. Aims This study aimed to investigate the effects of different photoperiod treatments on thyroid organ weight and serum thyroid hormone concentrations of broilers by use of biochemical and histological methods. Methods After the hatching, 120 broiler chicks (Ross) were divided into two main groups according to sex. Both groups were then split into two sub-groups based on photoperiod treatment: 16 h (i.e. 16 h light:8 h dark) and 24 h (24 h light:0 h dark). Thyroid gland and blood samples of six animals from each group were obtained after slaughtering at 7-day intervals from Day 14 after hatching to Day 42. Serum concentrations of free triiodothyronine (FT3), free thyroxin (FT4) and thyroid-stimulating hormone (TSH) were determined by the chemiluminescence method for all groups. Thyroid weight, bodyweight and thyroid follicle diameter were also measured. Key results Thyroid weight:bodyweight ratio generally started to increase from Day 14 to Day 42, with no significant (P &gt; 0.05) difference among the groups at the same age. For both male and female broiler chicks, morphometric measures increased as birds grew. Serum FT3 and TSH concentrations slightly decreased and serum FT4 concentrations increased in growing chicks of both sexes. Conclusions Extending the photoperiod from 16 to 24 h had no effects on thyroid gland development or functions in terms of both biochemical and morphometric parameters in broiler chicks. Implications Continuous light has minimal effects on thyroid functions of growing broiler chicks to Day 42.