Alert for the high prevalence of vitamin D deficiency in adolescents in a large Brazilian sample.

OBJECTIVE: To estimate the prevalence of vitamin D deficiency and severe deficiency in children and adolescents, in a large Brazilian sample. METHODOLOGY: Results of 413,976 25(OH)D measurements in children and adolescents aged 0 to 18 years collected between 01/2014 and 10/2018 were obtained from the database of a Clinical Laboratory. In this population, 25 hydroxyvitamin D concentrations below 20 ng/mL are considered deficient, and below 12 ng/mL as severe deficiency. All measurements were performed by immunoassay and the results were distributed by gender, age group, seasonality, and latitude. RESULTS: The mean of 25(OH)D levels was 29.2 ng/mL with a standard deviation of 9.2 ng/mL. Of the total samples, 0.8% had a concentration < 12 ng/mL, and 12.5% of the samples had a concentration < 20 ng/mL, with a higher prevalence in females. Children under 2 years of age had the lowest prevalence. The effects of latitude and seasonality were quite evident. In samples of female adolescents from the southern region in winter, 36% of vitamin D deficiency and 5% of severe deficiency were found. CONCLUSION: In this large number of measurements of 25(OH)D in children and adolescents, 12.5% had a deficiency and 0.8% had severe deficiency. A greater deficiency was observed among adolescents, especially females, which raises questions about the need for supplementation during this period of life.

False diagnosis of recurrent thyroid carcinoma: the importance of testing for heterophile antibodies.

Thyroglobulin (Tg) levels are important to predict recurrence in differentiated thyroid cancer patients.However, false-positive results can hence the request of unnecessary tests and treatments. We reported two cases of interference in thyroglobulin measurement and the workup to investigate them. Both patients achieved an excellent response to therapy after total thyroidectomy and one patient had also received radioiodine treatment. During the follow-up, Tg levels increased and there was no evidence of recurrent disease in the imaging studies. The Tg levels by the Access platform were positive but the results by Elecsys platform and LC-MS/MS were undetectable, leading to the hypothesis of heterophile antibodies (HAbs) interference. The possibility of HAbs interference must be considered when the Tg levels do not fit in the clinical picture. The measurement of Tg by another immunoassay or by LC-MS/MS may be useful in these situations.

Thyroid dysfunction alters gene expression of proteins related to iron homeostasis and metabolomics in male rats.

Thyroid hormones (THs) are crucial in bodily functions, while iron is essential for processes like oxygen transport. Specialized proteins maintain iron balance, including ferritin, transferrin, ferroportin, and hepcidin. Research suggests that THs can influence iron homeostasis by affecting mRNA and protein expression, such as ferritin and transferrin. Our study focused on male rats to assess mRNA expression of iron homeostasis-related proteins and metabolomics in thyroid dysfunction. We found altered gene expression across various tissues (liver, duodenum, spleen, and kidney) and identified disrupted metabolite patterns in thyroid dysfunction. These findings highlight tissue-specific effects of thyroid dysfunction on essential iron homeostasis proteins and provide insights into associated metabolic changes. Our research contributes to understanding the intricate interplay between thyroid hormones and iron balance. By unveiling tissue-specific gene expression alterations and metabolic disruptions caused by thyroid dysfunction, our work lays a foundation for future investigations to explore underlying mechanisms and develop targeted strategies for managing iron-related complications in thyroid disorders.

Metabolomic analysis of follicular fluid from women with Hashimoto thyroiditis.

Hashimoto thyroiditis is an autoimmune disease characterized by hypothyroidism and a high level of anti-thyroid autoantibodies. It has shown to negatively impact female fertility; however, the mechanisms are unclear. Ovarian follicular fluid appears to be the key to understanding how Hashimoto thyroiditis affecst fertility. Thus, we aimed to evaluated the metabolic profile of follicular fluid and antithyroid autoantibody levels in the context of Hashimoto thyroiditis. We collected follicular fluid from 61 patients, namely 38 women with thyroid autoantibody positivity and 23 women as negative controls, undergoing in vitro fertilization treatment. Follicular fluid samples were analyzed using metabolomics, and thyroid autoantibodies were measured. Fifteen metabolites with higher concentrations in the follicular fluid samples from Hashimoto thyroiditis were identified, comprising five possible affected pathways: the glycerophospholipid, arachidonic acid, linoleic acid, alpha-linolenic acid, and sphingolipid metabolism pathways. These pathways are known to regulate ovarian functions. In addition, antithyroglobulin antibody concentrations in both serum and follicular fluid were more than tenfold higher in women with Hashimoto thyroiditis than in controls. Our data showed that the metabolic profile of follicular fluid is altered in women with Hashimoto thyroiditis, suggesting a potential mechanistic explanation for the association of this disease with female infertility.

Treatment of Graves' disease in Brazil: results of a survey among endocrinologists.

Objective: The objective of the study was to determine how physicians in Brazil manage Graves' disease in different scenarios including extrathyroidal manifestations. Materials and methods: This study was conducted via a digital survey. The respondents (n = 573) answered multiple-choice questions based on a clinical case and variations of the case regarding laboratory and imaging evaluation, treatment choice, and follow-up. Results: The preferred initial treatment chosen by 95% of the respondents was ATD with a preferred treatment duration of 18-24 months. For 5% of the respondents, RAI was the initial treatment of choice. None of the respondents chose thyroidectomy. When presented with a patient with a desire for pregnancy in the near future, most respondents (69%) opted for ATD as the initial treatment. For a patient with signs of mild to moderate Graves' orbitopathy, ATD remained the initial therapy for 93.9% of the respondents. For patients initially treated with ATD with disease recurrence after ATD interruption, most respondents (60%) chose definitive treatment with RAI. A similar survey published in 2011 by Burch and cols. had results comparable to those of the present survey but with a higher proportion of respondents choosing RAI (45% in the 2011 survey versus 5% in the present survey). Conclusion: Brazilian endocrinologists choose ATD as the initial management of Graves' disease, and most choose RAI as a definitive treatment for a patient with relapse after ATD therapy.

Treatment of Graves' disease in Brazil: results of a survey among endocrinologists

ABSTRACT Objective: The objective of the study was to determine how physicians in Brazil manage Graves' disease in different scenarios including extrathyroidal manifestations. Materials and methods: This study was conducted via a digital survey. The respondents (n = 573) answered multiple-choice questions based on a clinical case and variations of the case regarding laboratory and imaging evaluation, treatment choice, and follow-up. Results: The preferred initial treatment chosen by 95% of the respondents was ATD with a preferred treatment duration of 18-24 months. For 5% of the respondents, RAI was the initial treatment of choice. None of the respondents chose thyroidectomy. When presented with a patient with a desire for pregnancy in the near future, most respondents (69%) opted for ATD as the initial treatment. For a patient with signs of mild to moderate Graves' orbitopathy, ATD remained the initial therapy for 93.9% of the respondents. For patients initially treated with ATD with disease recurrence after ATD interruption, most respondents (60%) chose definitive treatment with RAI. A similar survey published in 2011 by Burch and cols. had results comparable to those of the present survey but with a higher proportion of respondents choosing RAI (45% in the 2011 survey versus 5% in the present survey). Conclusion: Brazilian endocrinologists choose ATD as the initial management of Graves' disease, and most choose RAI as a definitive treatment for a patient with relapse after ATD therapy.

Screening, diagnosis and management of hypothyroidism in pregnancy: Number 10 - October 2022

Key points Pregnancy places a metabolic overload on the maternal thyroid, especially in the first trimester, mainly because of the demand imposed by the conceptus. The fetal thyroid becomes functionally mature only around pregnancy week 20. Until then, the fetus depends on the transfer of maternal thyroid hormones (THs). Thyroid hormones are essential for the adequate fetal neurofunctional and cognitive development. Hypothyroidism brings higher risks of obstetric and fetal complications, namely, first-trimester miscarriage, preeclampsia and gestational hypertension, placental abruption, prematurity, low birth weight, and higher perinatal morbidity and mortality. Primary hypothyroidism (involvement of the gland with difficulty in producing and/or releasing TH) is the most common form of disease presentation, with the main etiology of Hashimoto's thyroiditis of autoimmune origin. In about 85%-90% of cases of Hashimoto's thyroiditis, antithyroid antibodies are present; the antithyroperoxidase (ATPO) is the most frequent. Positivity for ATPO is determined when circulating values exceed the upper limit of the laboratory reference. It implies greater risks of adverse maternal-fetal outcomes. Such a correlation occurs even in ranges of maternal euthyroidism. The critical point for the diagnosis of hypothyroidism during pregnancy is an elevation of thyroid-stimulating hormone (TSH). The measurement of free thyroxine (FT4) differentiates between subclinical and overt hypothyroidism. In subclinical hypothyroidism, FT4 is within the normal range, whereas in overt hypothyroidism, FT4 values are below the lower limit of the laboratory reference. Treatment of hypothyroidism is performed with levothyroxine (LT4) replacement with the aim of achieving adequate TSH levels for pregnancy. Some women have a previous diagnosis of hypothyroidism, and may or may not be compensated at the beginning of pregnancy. Even in compensated cases, the increase in LT4 dose is necessary as soon as possible. In the postpartum period, adjustment of the LT4 dose depends on the condition of previous disease, on the positivity for ATPO, and also on the value of LT4 in use at the end of pregnancy. Recommendations In places with full technical and financial conditions, TSH testing should be performed for all pregnant women (universal screening) as early as possible, ideally at the beginning of the first trimester or even in preconception planning. In places with less access to laboratory tests, screening is reserved for cases with greater risk factors for decompensation, namely: previous thyroidectomy or radioiodine therapy, type 1 diabetes mellitus or other autoimmune diseases, presence of goiter, previous history of hypo or hyperthyroidism or previous ATPO positivity. The TSH dosage should be repeated throughout pregnancy only in these cases. The diagnosis of hypothyroidism is made from the TSH value > 4.0 mIU/L. Pregnant women with previous hypothyroidism, overt hypothyroidism diagnosed during pregnancy or those with the above-mentioned higher risk factors for decompensation should be referred for risk antenatal care, preferably in conjunction with the endocrinologist. Overt hypothyroidism in pregnancy is identified when TSH > 10 mIU/L, and treatment with LT4 is readily recommended at an initial dose of 2 mcg/kg/day. TSH values > 4.0 mUI/L and ≤ 10.0 mUI/L require FT4 measurement with two diagnostic possibilities: overt hypothyroidism when FT4 levels are below the lower limit of the laboratory reference, or subclinical hypothyroidism when FT4 levels are normal. The treatment for subclinical hypothyroidism is LT4 at an initial dose of 1 mcg/kg/day, and the dose should be doubled upon diagnosis of overt hypothyroidism. In cases of TSH > 2.5 and ≤ 4.0 mIU/L, if there are complete conditions, ATPO should be measured. If positive (above the upper limit of normal), treatment with LT4 at a dose of 50 mcg/day is indicated. If conditions are not complete, the repetition of the TSH dosage should be done only for cases at higher risk. In these cases, treatment with LT4 will be established when TSH > 4.0 mIU/L at a dose of 1 mcg/kg/day; if needed, the dose can be adjusted after FT4 evaluation. Women with previous hypothyroidism should have their LT4 dose adjusted to achieve TSH < 2.5 mIU/L at preconception. As soon as they become pregnant, they need a 30% increase in LT4 as early as possible. In practice, they should double the usual dose on two days a week. Levothyroxine should be given 30-60 minutes before breakfast or three hours or more after the last meal. Concomitant intake with ferrous sulfate, calcium carbonate, aluminum hydroxide and sucralfate should be avoided. The target of LT4 therapy during pregnancy is to achieve a TSH value < 2.5 mIU/L. Once the therapy is started, monthly control must be performed until the mentioned goal is reached. In the postpartum period, women with previous disease should resume the preconception dose. Cases diagnosed during pregnancy in use of LT4 ≤ 50 mcg/day may have the medication suspended. The others should reduce the current dose by 25% to 50% and repeat the TSH measurement in six weeks. Cases of ATPO positivity are at higher risk of developing postpartum thyroiditis and de-escalation of LT4 should be performed as explained.

Alternation between toxic and proliferative effects of Roundup® on human thyroid cells at different concentrations.

Endocrine-disrupting and carcinogenic effects of glyphosate have long been suspected, but little is known about the effect of compounds used in real life at different concentrations, neither in normal nor in thyroid tumor cells. As cancer cells may have different sensitivities and the effect of the product containing glyphosate may be different from that produced by the active ingredient alone, including the Acceptable Occupational Exposure Level (AOEL=160µg/L) and the Acceptable Daily Intake (ADI=830µg/L) determined by ANVISA, we used two human thyroid-derived cell lines, Nthy-ori 3-1 (from normal follicular cells) and TPC-1 (from papillary carcinoma), to test 15 different concentrations of Roundup® Original DI. Trypan blue (TB), CCK-8 and BrdU assays were used to evaluate cytotoxicity, metabolic activity and proliferation with 24h and 48h exposures in technical and biological triplicates. TB showed an important toxic effect, especially after 24h of exposure, in both cell lines. The AOEL concentration caused the death of 43% and 50% of the Nthy-ori and TPC-1 cells, respectively, in 24 h, while ADI resulted in 35% and 58% of cell death. After 48h of exposure, AOEL and ADI caused a lower number of dead Nthy-ori (33% and 18%) and TPC-1 (33% and 37%) cells, respectively, suggesting that the toxic effect of the product disappears and/or both strains have repair mechanisms that protect them from longer exposures. On the other hand, the CCK-8 assay showed that small concentrations of Roundup have a proliferative effect: 6.5µg/L increased the number of both Nthy-ori and TPC-1 cells at 24h, and the BrdU assay confirmed the stimulatory effect with a 321% increase in the absorbance of Nthy-ori cells at 48h. The herbicide produced even more frequent increases in the BrdU absorbance of TPC-1 cells, mainly at 24h. We conclude that thyroid cells exposed to Roundup present a nonmonotonic dual dose-response curve. Low concentrations of the pesticide, considered acceptable, cause significant cell death but also have an important proliferative effect, especially on TPC-1 cells. This herbicide, widely used around the world, may play a role in the increased incidence rate of thyroid nodules and cancer that has been observed in recent decades.

No association between vitamin D status and COVID-19 infection in São Paulo, Brazil

ABSTRACT In recent years the immunomodulatory actions of vitamin D, a steroid hormone, have been extensively studied. In 2020, due to the COVID-19 pandemic, the question arose as to 25(OH)D status would be related to susceptibility to SARS-CoV-2 infection, since several studies pointed out a higher prevalence and severity of the disease in populations with low levels of 25(OH)D. Thus, we investigated the 25(OH)D levels in adults "Detected" positive for SARS CoV-2 by RT-PCR (reverse transcriptase polymerase chain reaction) test, and in negative controls, "not Detected", using the Fleury Group's examination database, in Sao Paulo, Brazil. Of a total of 14.692 people with recent assessments of 25(OH)D and RT-PCR tests for COVID-19, 2.345 were positive and 11.585 were negative for the infection. The groups did not differ in the percentage of men and women, or in the age distribution. There were no differences in the distribution of 25(OH)D between the two groups (p = 0.08); mean 25(OH)D of 28.8 ± 21.4 ng/mL and 29.6 ± 18.1 ng/mL, respectively. In the specific population studied, clinical, environmental, socioeconomic and cultural factors should have greater relevance than 25(OH)D in determining the susceptibility to COVID-19.

No association between vitamin D status and COVID-19 infection in São Paulo, Brazil.

In recent years the immunomodulatory actions of vitamin D, a steroid hormone, have been extensively studied. In 2020, due to the COVID-19 pandemic, the question arose as to 25(OH)D status would be related to susceptibility to SARS-CoV-2 infection, since several studies pointed out a higher prevalence and severity of the disease in populations with low levels of 25(OH)D. Thus, we investigated the 25(OH)D levels in adults "Detected" positive for SARS CoV-2 by RT-PCR (reverse transcriptase polymerase chain reaction) test, and in negative controls, "not Detected", using the Fleury Group's examination database, in Sao Paulo, Brazil. Of a total of 14.692 people with recent assessments of 25(OH)D and RT-PCR tests for COVID-19, 2.345 were positive and 11.585 were negative for the infection. The groups did not differ in the percentage of men and women, or in the age distribution. There were no differences in the distribution of 25(OH)D between the two groups (p = 0.08); mean 25(OH)D of 28.8 ± 21.4 ng/mL and 29.6 ± 18.1 ng/mL, respectively. In the specific population studied, clinical, environmental, socioeconomic and cultural factors should have greater relevance than 25(OH)D in determining the susceptibility to COVID-19.

Thyroxine replacement modifies changes in deiodinase and thyroid hormone transporter expression induced by subclinical hypothyroidism in rats.

PURPOSE: The potential benefits of treating subclinical hypothyroidism (SCH) are unclear and still controversial. Thus, we surgically induced SCH in rats and evaluated the effects of thyroxine (T4) replacement on the gene expression levels of deiodinases and thyroid hormone (TH) transporters in different tissues. METHODS: SCH was induced by hemithyroid electrocauterization. The control animals underwent the same surgical procedure but were not subjected to electrocauterization (sham). After 14 days, half of the SCH animals were treated with T4 (SCH + T4). At the end of the experimental protocol, all of the rats were euthanized, serum hormone concentrations were measured, and RNA analyses were performed on different tissues and organs. RESULTS: Consistent with previous studies, we observed increased TSH levels, normal TH levels, and reduced hypothalamic TRH expression in the SCH group. Additionally, Dio2 mRNA expression was downregulated in the hippocampus and pituitary, and Dio1 was upregulated in the kidney and pituitary of the SCH animals. The changes in Dio3 expression were tissue-specific. Concerning TH transporters, Mct10 expression was upregulated in the pituitary, kidney, hypothalamus, and hippocampus, and Mct8 expression was downregulated in the kidney of the SCH group. Crym expression was upregulated in the kidney and pituitary. Notably, T4 replacement significantly attenuated serum TSH levels and reverted Dio1, Dio2, Mct10, and Crym expression in the pituitary, hippocampus, and kidney to levels that were similar to the sham group. Tissue-specific responses were also observed in the liver and hypothalamus. CONCLUSION: Our results indicate that treatment of SCH should be considered before the appearance of clinical symptoms of hypothyroidism.

Androgens by immunoassay and mass spectrometry in children with 46,XY disorder of sex development.

OBJECTIVE: Steroid measurement is a challenge in pediatric endocrinology. Currently, liquid chromatography with tandem mass spectrometry (LC-MS/MS) is considered a gold standard for this purpose. The aim of this study was to compare both LC-MS/MS and immunoassay (IA) for androgens before and after human recombinant chorionic gonadotropin (rhCG) stimulus in children with 46,XY disorders of sex development (DSD). METHODS: Nineteen patients with 46,XY DSD were evaluated; all of them were prepubertal and non-gonadectomized. Testosterone, dihydrotestosterone (DHT), DHEA and androstenedione were measured by IA and LC-MS/MS before and 7 days after rhCG injection. The correlation between IA and LC-MS/MS was analyzed by the intraclass correlation coefficient (ICC) and Spearman's rank correlation coefficient (SCC). For concordance analysis the Passing and Bablok (PB) regression and the Bland and Altman (BA) method were used. RESULTS: Testosterone showed excellent correlation (ICC = 0.960 and SCC = 0.964); DHT showed insignificant and moderate correlations as indicated by ICC (0.222) and SCC (0.631), respectively; DHEA showed moderate correlation (ICC = 0.585 and SCC = 0.716); and androstenedione had poor and moderate correlations in ICC (0.363) and SCC (0.735), respectively. Using the PB method, all hormones showed a linear correlation, but proportional and systematic concordance errors were detected for androstenedione, systematic errors for testosterone and no errors for DHEA and DHT. By the BA method, there was a trend of IA to overestimate testosterone and androstenedione and underestimate DHEA and DHT when compared to LC-MS/MS. CONCLUSION: Traditional IA should be replaced by LC-MS/MS for the androgens measurement in prepubertal children whenever is possible.

Structural insights revealed by two novel THRB mutations.

PURPOSE: Among the inheritable forms of impaired sensitivity to thyroid hormone, resistance to thyroid hormone (RTH) due to mutations in the thyroid hormone receptor beta gene (THRB) is the first and best known described defect, revealing a wide phenotypic variability with an incompletely understood physiopathology. The objective of this study was to evaluate two novel mutations in THRB, N331H and L346R, in an attempt to provide a rational understanding of the harmful effects caused by them. METHODS: The mutations of two patients with RTHß were reproduced for analysis of gene transactivation by dual-luciferase reporter assay, and for molecular modeling for crystallography-based structural assessment. Serum measurements of TSH and FT4 were performed to compare the thyrotrophic resistance to thyroid hormone between RTHß patients and controls. RESULTS: Both mutants showed impaired gene transactivation, with greater damage in L346R. Molecular modeling suggested that the damage occurring in N331H is primarily due to reduced strength of the hydrogen bonds that stabilize T3 in its ligand-binding cavity (LBC), whereas in L346R, the damage is more marked and is mainly due to changes in hydrophobicity and molecular volume inside the LBC. Hormonal dosages indicated that the L346R mutant exhibited greater thyrotrophic resistance than N331H. CONCLUSIONS: This study provides a rational understanding of the effects of mutations, indicating deleterious structural changes in the LBC in both THR, and discloses that not only the position of the mutation but, notably, the nature of the amino acid exchange, has a cardinal role in the functional damage of the receptor.

Maternal glyphosate-based herbicide exposure alters antioxidant-related genes in the brain and serum metabolites of male rat offspring.

In response to the rapid development of genetically engineered glyphosate-tolerant crops, the use of glyphosate-based herbicides (GBHs), in agriculture, has increased substantially. Currently, it is estimated that 747 million kg of GBHs are applied per year. Although several epidemiological studies have demonstrated that there are health risks associated with GBH exposure, the effects these chemicals have on the oxidative and inflammatory response in the brain are still unclear. In fact, alterations in these processes could contribute to the development of neurological diseases, such as Alzheimer's disease and autism spectrum disorders. The present study exposed pregnant rats to GBH and evaluated changes in the expression of genes related to oxidnte defense and inflammation response and monitored the serum metabolome in the adult male offspring. Pregnant Wistar rats were administered distilled water or Roundup®, at either 5 and 50 mg/kg/day, (p.o.) from gestational day (GD) 18 to postnatal day (PND) 5. There was a significant increase in the gene expression levels of Neuroglobin (Ngb - oxygen storage and tissue protection) (105%, p = 0.031), Glutathione Peroxidase 1 (Gpx1 - oxidative stress) (95%, p = 0.005), Prostaglandin-Endoperoxidase Synthase 1 (Ptgs1 - inflammation) (109%, p = 0.033) and Hypoxia inducible factor 1 subunit alpha (Hif1α - oxygen sensor) (73%, p = 0.017), in the cerebellum of PND90 rats perinatally exposed to 50 mg GBH/kg/day. Moreover, both GBH-exposed groups displayed a significant decrease in the expression of Catalase (Cat - oxidative stress) (49%, p = 0.003; and 31% p = 0.050, respectively) expression, in the cortex. Serum metabolites analyses, from the same animals of each group, demonstrated that there were significant changes in the concentrations of lysophosphatidylcholine and phosphatidylcholine, which have been associated with neurodegenerative diseases. The results of the present study suggest GBH exposure during pregnancy alters the expression of genes associated with oxidant defense, inflammation and lipid metabolism. It is plausible that maternal GBH exposure could have lasting neuronal effects on the offspring later in life.

Evaluation of neuroglobin and cytoglobin expression in adult rats exposed to silver nanoparticles during prepubescence.

Silver nanoparticles (AgNPs) are clusters of silver atoms with diameters that range from 1 to 100 nm. Due to the various shapes and large surface areas, AgNPs have been employed in the food and textile industries and medical fields. Therefore, because of the widespread use of these compounds, the aim of this study was to evaluate the effect of AgNP exposure on the gene and protein expression levels of Neuroglobin (Ngb) and Cytoglobin (Cygb), in the rat cortex, hippocampus and cerebellum. Post-natal day (PND) 21 male Wistar rats were randomly divided into three groups. One group received 15 µg/kg body weight of AgNP by gavage another group received 30 µg/kg and the control group that received saline, from PND23 to PND58. On PND102 the animals were euthanized and the cortex, hippocampus and cerebellum were isolated and evaluated for gene and protein expression levels of Nbg and Cygb. The results demonstrated that the 30 µg/kg AgNP group displayed increased gene and protein expression of Cygb in the cortex. In the Hippocampus, AgNP exposure did not modulate gene or protein expression levels of Ngb and Cygb. In cerebellum the Ngb gene and protein expression was increased with both doses of AgNP. AgNP exposure during prepubescence can modulate the gene and protein expression levels of Ngb and Cygb in adulthood. Furthermore, the observed modulation was specific to the cerebellum, and cortex, and was dose dependent.

Thyroid Function Disruptors: from nature to chemicals.

The modern concept of thyroid disruptors includes man-made chemicals and bioactive compounds from food that interfere with any aspect of the hypothalamus-pituitary-thyroid axis, thyroid hormone biosynthesis and secretion, blood and transmembrane transport, metabolism and local action of thyroid hormones. This review highlights relevant disruptors that effect populations through their diet: directly from food itself (fish oil and polyunsaturated fatty acids, pepper, coffee, cinnamon and resveratrol/grapes), through vegetable cultivation (pesticides) and from containers for food storage and cooking (bisphenol A, phthalates and polybrominated diphenyl ethers). Due to the vital role of thyroid hormones during every stage of life, we review effects from the gestational period through to adulthood, including evidence from in vitro studies, rodent models, human trials and epidemiological studies.

Novel immunoassay for TSH measurement in rats.

Measuring thyroid hormones is an important aspect for the study of metabolism and for monitoring diseases in both human and animal models. The traditional method for hormone measurement in rats is the radioimmunoassay (RIA). However, the RIA is associated with some practical disadvantages, including the use of radioactive material, the need for specialized equipment and expert staff, the short shelf-life of kits according to the half-life of the radioisotope and high costs. The objective of this study was to develop a new cost-effective method for measuring TSH levels in rats that avoids the use of radioactive material. We developed an in-house competitive immunoassay using a reference standard, polyclonal antibody produced in rabbits and biotinylated antigen. This method was tested in 64 Wistar rats that were divided into a control group (n = 41) and a group with hypothyroidism (n = 23). Our assay demonstrated an analytical sensitivity of 0.24 ng/mL (n = 12) and an intra-assay coefficient of variation (CV) of 8.9% for sera with TSH levels of 1.5 ng/mL and 13.2% for sera with TSH levels of 17.5 ng/mL (n = 14). The inter-assay CV was 13.5% for sera with TSH levels of 1.4 ng/mL and 14.5% for TSH levels of 18.2 ng/mL (n = 5). The analysis of mean TSH levels in control rats (5.06 ± 0.5701) and hypothyroid rats (51.09 ± 5.136) revealed a statistically significant difference (p < 0.001) between the groups. This method showed good sensitivity, can be automated and is low-cost compared with RIA. Our method offers a viable alternative for TSH measurement in rats.