The Effect of Vitamin D Supplementation on Hypothyroidism in the Randomized Controlled D-Health Trial.

Background: Hypothyroidism is common, and in iodine-sufficient areas, it is primarily caused by autoimmune destruction of the thyroid gland. Observational studies have consistently shown an inverse association between serum 25-hydroxyvitamin D concentration and autoimmune diseases; however, there is a lack of evidence from randomized controlled trials to support a benefit of vitamin D supplementation, particularly for autoimmune thyroid diseases. We, therefore, aimed to assess the effect of vitamin D supplementation on the incidence of hypothyroidism. Methods: We analyzed data from the D-Health Trial (n = 21,315), a randomized double-blind placebo-controlled trial of 60,000 international units per month of supplemental vitamin D3 among Australians aged 60 years and over. Hypothyroidism, a tertiary outcome of the D-Health Trial, was defined by treatment with levothyroxine, ascertained through linkage with the Australian Pharmaceutical Benefits Scheme. The outcome was time to first prescription of levothyroxine. We began follow-up at 12 months after randomization; people who had died or who had been dispensed levothyroxine during the first year were excluded. Flexible parametric survival models were used to assess the effect of vitamin D supplementation on hypothyroidism, overall and within strata defined by age, sex, body mass index, and predicted baseline vitamin D status. Results: We included 17,851 participants in the main analysis (vitamin D = 8939; placebo = 8912). During a median follow-up of 4.1 years (interquartile range 4.1-4.1), 293 participants developed hypothyroidism (vitamin D = 138 [1.5%]; placebo = 155 [1.7%]). Vitamin D supplementation did not significantly reduce the incidence of hypothyroidism (overall hazard ratio [HR] 0.89; 95% confidence interval [CI] 0.71-1.12). There was some suggestion of an effect in females (overall HR 0.78; CI 0.58-1.06) but not in males (overall HR 1.06; CI 0.74-1.50; p interaction 0.20). Conclusions: Vitamin D supplementation did not reduce the incidence of hypothyroidism overall; however, the possible beneficial effect observed in females warrants further investigation. Clinical Trial Registration: Australian New Zealand Clinical Trials Registry: ACTRN12613000743763.

High-dose radiation exposure and hypothyroidism: aetiology, prevention and replacement therapy.

Without any doubt, high dose radiation exposure can induce hypothyroidism. However, there are open questions related to the mechanisms of its induction, corresponding dose thresholds and possible countermeasures. Therefore, this review addresses the aetiology, prevention and therapy of radiation induced hypothyroidism. External beam radiotherapy with several 10 Gy to the head and neck region and radioiodine therapy with several 100 Gy thyroid absorbed dose can destroy the thyroid gland and can induce autoantibodies against thyroid tissue. According to recent literature, clinical hypothyroidism is observed at threshold doses of ∼10 Gy after external beam radiotherapy and of ∼50 Gy after radioiodine therapy, children being more sensitive than adults. In children and adolescents exposed by the Chernobyl accident with mean thyroid absorbed doses of 500-800 mGy, subclinical hypothyroidism has been detected in 3%-6% of the cases with significant correlation to thyroid absorbed doses above 2.5 Gy. In case of nuclear emergencies, iodine thyroid blocking (ITB) is the method of choice to keep thyroid absorbed doses low. Large doses of stable iodine affect two different steps of internalization of radioiodine (transport and organification); perchlorate affecting the transport only may be an alternative to iodine. Administered before radioiodine incorporation, the effect of 100 mg iodide or more is still about 90% after 1 days, 80% after 2 days, and 50% or less after 3 days. If administered (too) late after exposure to radioiodine, the theoretically expected protective effect of ITB is about 50% after 6 h, 25% after 12 h, and about 6% after 24 h. In case of repeated or continuous exposure, repeated administration of 50 mg of iodide daily is indicated. If radiation-induced hypothyroidism cannot be avoided, thyroid hormone replacement therapy with individualized dosing and regular monitoring in order to maintain thyroid-stimulating hormone levels within the normal range ensures normal life expectancy.

Iodine supplementation for pregnant women: a cross-sectional national interventional study.

BACKGROUND: Although Iran has been considered iodine replete since 2000, the first national survey of iodine intake among Iranian pregnant women in 2014 indicated that despite the adequate intake of iodine by the general population, this vulnerable group has moderate iodine deficiency. Therefore, in this national cross-sectional interventional study, we aimed to assess the iodine intake and thyroid function of Iranian pregnant women 2 years after implementing national iodine supplementation for this vulnerable group. MATERIALS AND METHODS: In this cross-sectional study, we conducted a national interventional survey of pregnant women. A total of 1200 pregnant women (400 women from each trimester) from 12 provinces of Iran were recruited from the antenatal care clinics from October 2018 to March 2019. The median urinary iodine concentration (MUIC), as an indicator of iodine status in three spot urine samples, was measured, along with the serum total T4 (TT4), thyrotropin (TSH), thyroglobulin (Tg), thyroid peroxidase antibody (TPO-Ab), and iodine content of household salt. RESULTS: The mean age of the cohort was 28 ± 6.2 years, with the mean gestational age of 22.7 ± 13.0 weeks. The overall MUIC (IQR) of pregnant women was 188 µg/L (124.2-263 µg/L). Also, the MUICs in the three trimesters of pregnancy were 174 µg/L (110-254), 175 µg/L (116-251), and 165 µg/L (114-235), respectively. The MUICs ≥ 150, 100-149, and < 100 µg/L were found in 63, 19.8, and 16.2% of the subjects, respectively. The mean TT4 level was 12 ± 4.5 µg/dL, and the median (IQR) level of TSH was 2.37 mIU/L (1.66-3.18 mIU/L). According to our local reference range, 118 (10.5%) pregnant women had subclinical hypothyroidism, 6 (0.53%) women had isolated hypothyroxinemia, and 65 (5.7%) women were TPO-Ab positive. Also, the median (IQR) level of Tg was 10.08 µg/dL (5.7-20.4 µg/dL), and the median iodine content of household salt was 29.6 µg/g; the iodine content was ≥ 30 µg/g in 85% of household salt. The results showed that more than 95% of households were under iodized salt coverage. CONCLUSION: The results of this study indicated that iodine supplementation with at least 150 µg of iodine per day improved the iodine intake of pregnant women. Except for subclinical hypothyroidism, the prevalence of clinical hypothyroidism, clinical/subclinical thyrotoxicosis, TPO-Ab positivity, and isolated hypothyroxinemia decreased significantly, which emphasizes the importance of iodine supplementation during pregnancy.

Does thyroid-sparing total laryngectomy decrease the risk of hypothyroidism?

BACKGROUND: Thyroid lobectomy is recommended with total laryngectomy for laryngeal cancer in the National Comprehensive Cancer Network ('NCCN') guidelines. However, it is associated with a 32-89 per cent risk of hypothyroidism, with or without adjuvant radiotherapy. OBJECTIVE: The study aimed to determine whether preserving the whole thyroid, compared to a single lobe, does indeed significantly lower the incidence of hypothyroidism in the setting of total laryngectomy. METHOD: A retrospective study was conducted at Groote Schuur Hospital in Cape Town, South Africa. RESULTS: Eighty-four patients met the inclusion criteria. The overall incidence of hypothyroidism was 45.2 per cent. The incidence of hypothyroidism was significantly reduced in patients who underwent thyroid-sparing total laryngectomy compared to hemithyroidectomy (p = 0.037). Adjuvant radiotherapy was associated with a higher incidence of hypothyroidism (p = 0.001). CONCLUSION: Thyroid-preserving laryngectomy should be advocated in carefully selected patients with advanced laryngeal carcinoma, as it reduces the incidence of hypothyroidism.

Risk of Iodine Deficiency in Extremely Low Gestational Age Newborns on Parenteral Nutrition.

Iodine is an essential component of thyroid hormones, which play a critical role in neurodevelopment. The iodine status of pregnant women and their newborns is not checked routinely. Extremely Low Gestational Age Newborns do not receive Iodine supplementation while on parenteral nutrition (PN). We measured urine iodine levels and thyroid function tests in 50 mother-infant dyads at birth, at 1 week, 1, 2, 3 months and near discharge. We correlated maternal and neonatal urine iodine levels with thyroid functions and measured iodine levels in milk and PN. In our study, 64% of mothers were iodine deficient at the time of delivery, their free T4 levels were 0.48 (0.41-0.54) ng/dL with normal thyroid-stimulating hormone (TSH). Iodine levels were thirty-fold higher in extremely low gestational age newborns (ELGAN) exposed to iodine comparing to full terms (p < 0.001), but this effect lasted <1 week. At 1 month of age, ELGAN on PN developed iodine deficiency (p = 0.017) and had high thyroglobulin levels of 187 (156-271) ng/mL. Iodine levels improved with enteral feeds by 2 months of age (p = 0.01). Iodine deficiency is prevalent among pregnant women and ELGAN; in particular, those on PN are at risk of hypothyroidism. Iodine supplementation during pregnancy and postnatally should be considered to avoid iodine deficiency.

Iodine Status in Schoolchildren and Pregnant Women of Lazio, a Central Region of Italy.

The inhabitants of Lazio, similarly to those of other Italian regions, have been historically exposed to the detrimental effects of an inadequate intake of iodine. The latter is a micronutrient essential for the biosynthesis of thyroid hormones (TH). Iodine deficiency is responsible for a number of adverse effects on human health known as iodine deficiency disorders (IDD), the most common of which worldwide are goiter and hypothyroidism. In order to reduce IDD, a national salt iodination program was started in Italy in 2005. In this article we reviewed the available data regarding iodine intake in the Lazio population before and after the introduction of the national salt iodination program, in order to evaluate its efficacy and the eventual problem(s) limiting its success. On the whole, the information acquired indicates that, following the introduction of the program, the dietary iodine intake in the Lazio population is improved. There is, however, still much work ahead to ameliorate the iodine prophylaxis in this region. In fact, although a generally adequate iodine intake in school-age children has been observed, there are still areas where a mild iodine insufficiency is present. Moreover, two independent epidemiological surveys on pregnant women evidenced a low urinary iodine concentration with respect to the reference range conceived by the World Health Organization. These findings demonstrate the need for greater attention to the iodine prophylaxis by health care providers (i.e., obstetricians, gynecologists, pediatricians, etc.), and the implementation of effective advertising campaigns aimed at increasing the knowledge and awareness of the favorable effects of iodine supplementation on population health.

Analysis of the protective effects of γ-aminobutyric acid during fluoride-induced hypothyroidism in male Kunming mice.

CONTEXT: Compounds to treat hypothyroidism in the absence of cardiac side effects are urgently required. In this regard, γ-aminobutyric acid (GABA) has gained interest due to its anti-anxiolytic, antihypertensive and antioxidant properties, and reported benefits to the thyroid system. OBJECTIVE: We investigated the ability of GABA to ameliorate fluoride-induced thyroid injury in mice, and investigated the mechanism(s) associated with GABA-induced protection. MATERIALS AND METHODS: Adult male Kumning mice (N = 90) were exposed to NaF (50 mg/kg) for 30 days as a model of hypothyroidism. To evaluate the effects of GABA administration, fluoride-exposed mice received either thyroid tablets, or low (25 mg/kg), medium (50 mg/kg) or high (75 mg/kg) concentrations of pure GABA orally for 14 days groups (N = 10 each). The effects of low (50 mg/kg); medium (75 mg/kg) and high (100 mg/kg) concentrations of laboratory-separated GABA were assessed for comparison. Effects on thyroid hormone production, oxidative stress, thyroid function-associated genes, and side-effects during therapy were measured. RESULTS: GABA supplementation in fluoride-exposed mice significantly increased the expression of thyroid TG, TPO, and NIS (P < 0.05), significantly improved the thyroid redox state (P < 0.05), modulated the expression of thyroid function-associated genes, conferred liver metabolic protection, and prevented changes to myocardial morphology, thus reducing side effects. Both pure and laboratory-separated GABA displayed comparative protective effects. DISCUSSION AND CONCLUSION: Our findings support the assertion that GABA exerts therapeutic potential in hypothyroidism. The design and use of human GABA trials to improve therapeutic outcomes in hypothyroidism are now warranted.

Maternal iodine dietary supplements and neonatal thyroid stimulating hormone in Gippsland, Australia.

BACKGROUND AND OBJECTIVES: Pregnant women are at particular risk of iodine deficiency due to their higher iodine requirements. Iodine is known to be essential for normal growth and brain development, therefore neonatal outcomes in mildly iodine deficient areas, such as Gippsland, are a critical consideration. This study aimed to investigate whether iodine supplementation prevented iodine insufficiency as determined by neonatal thyroid stimulating hormone (TSH) screening criteria. METHODS AND STUDY DESIGN: Gippsland-based women aged >=18 years, in their third trimester of pregnancy, provided self-reported information regarding their iodine supplement use and consent to access their offspring's neonatal TSH screening data. 126 women consented to participate, with 111 women completing all components of this study. RESULTS: Only 18.9% of participants followed the National Health and Medical Research Council (NHMRC) recommendation of 150 µg/day iodine supplement, with 42.3% of participants not taking any supplements, or taking supplements with no iodine or insufficient iodine. The remaining women (38.7%) were taking supplements with doses of iodine much higher (200-300 µg) than the NHMRC recommended dose or were taking multiple supplements containing iodine. When correlating iodine intake to their neonates' TSH, no correlation was found. When iodine supplementation usage was categorised as below, equal to, or above NHMRC recommendations there was no significant difference in neonatal TSH. CONCLUSION: This study found that iodine supplementation appeared to prevent maternal iodine insufficiency when measured against neonatal TSH screening criteria.

Physiological serum 25-hydroxyvitamin D concentrations are associated with improved thyroid function-observations from a community-based program.

PURPOSE: Vitamin D deficiency has been associated with an increased risk of hypothyroidism and autoimmune thyroid disease. Our aim was to investigate the influence of vitamin D supplementation on thyroid function and anti-thyroid antibody levels. METHODS: We constructed a database that included 11,017 participants in a health and wellness program that provided vitamin D supplementation to target physiological serum 25-hydroxyvitmain D [25(OH)D] concentrations (>100 nmol/L). Participant measures were compared between entry to the program (baseline) and follow-up (12 ± 3 months later) using an intent-to-treat analysis. Further, a nested case-control design was utilized to examine differences in thyroid function over 1 year in hypothyroid individuals and euthyroid controls. RESULTS: More than 72% of participants achieved serum 25(OH)D concentrations >100 nmol/L at follow-up, with 20% above 125 nmol/L. Hypothyroidism was detected in 2% (23% including subclinical hypothyroidism) of participants at baseline and 0.4% (or 6% with subclinical) at follow-up. Serum 25(OH)D concentrations ≥125 nmol/L were associated with a 30% reduced risk of hypothyroidism and a 32% reduced risk of elevated anti-thyroid antibodies. Hypothyroid cases were found to have higher mean serum 25(OH)D concentrations at follow-up, which was a significant positive predictor of improved thyroid function. CONCLUSION: The results of the current study suggest that optimal thyroid function might require serum 25(OH)D concentrations above 125 nmol/L. Vitamin D supplementation may offer a safe and economical approach to improve thyroid function and may provide protection from developing thyroid disease.

Myo-inositol and selenium reduce the risk of developing overt hypothyroidism in patients with autoimmune thyroiditis.

OBJECTIVE: The beneficial effects obtained by myo-inositol in association with seleno-methionine in patients affected by subclinical hypothyroidism have been recently demonstrated. Here, we evaluate the immune-modulating effect of myo-inositol in association with seleno-methionine in patients with euthyroid autoimmune thyroiditis (AT). PATIENTS AND METHODS: Twenty-one consecutive Caucasian patients with newly diagnosed euthyroid chronic AT were evaluated. All subjects were treated with myo-inositol in association with selenium (600 mg/83 mg) tablets, twice per day, for six months. A complete thyroid assessment was done before the treatment, and after six months. RESULTS: After the treatment thyroid-stimulating hormone (TSH) levels significantly declined with respect to basal values, overall in patients with an initial TSH value in the high normal range (2.1

An extremely high dietary iodide supply forestalls severe hypothyroidism in Na+/I- symporter (NIS) knockout mice.

The sodium/iodide symporter (NIS) mediates active iodide (I-) accumulation in the thyroid, the first step in thyroid hormone (TH) biosynthesis. Mutations in the SLC5A5 gene encoding NIS that result in a non-functional protein lead to congenital hypothyroidism due to I- transport defect (ITD). ITD is a rare autosomal disorder that, if not treated promptly in infancy, can cause mental retardation, as the TH decrease results in improper development of the nervous system. However, in some patients, hypothyroidism has been ameliorated by unusually large amounts of dietary I-. Here we report the first NIS knockout (KO) mouse model, obtained by targeting exons 6 and 7 of the Slc5a5 gene. In NIS KO mice, in the thyroid, stomach, and salivary gland, NIS is absent, and hence there is no active accumulation of the NIS substrate pertechnetate (99mTcO4-). NIS KO mice showed undetectable serum T4 and very low serum T3 levels when fed a diet supplying the minimum I- requirement for rodents. These hypothyroid mice displayed oxidative stress in the thyroid, but not in the brown adipose tissue or liver. Feeding the mice a high-I- diet partially rescued TH biosynthesis, demonstrating that, at high I- concentrations, I- enters the thyroid through routes other than NIS.

Neuroprotective effects of Nigella sativa extract upon the hippocampus in PTU-induced hypothyroidism juvenile rats: A stereological study.

This study aimed to examine the neuroprotective effects of Nigella sativa (N. sativa) in the hippocampus of propylthiouracil (PTU)-induced hypothyroid rats during neonatal and juvenile growth. Twenty- five pregnant rats from early gestation (GD 0) were divided into five groups: (1) control (received drinking water), (2) PTU (received 0.005% PTU in drinking water), (3-5) PTU + NS 0.05%, PTU + NS 0.1%, PTU + NS 0.2% (along with PTU, received 0.05%, 0.1% and 0.2% W/V of N. sativa respectively) and treatment continued until postnatal day 60 (PN 60). The brains of male pups were removed for histological and stereological assessments. N. sativa extract significantly reduced the production of dark neurons and apoptotic cells in different areas of the hippocampus compared to the PTU group. Moreover, it significantly attenuated the effect of hypothyroidism on the volume reduction of the hippocampus. The results of the present study suggested that N. sativa extract has a potential ability to prevent the hippocampal neural damage after inducing hypothyroidism during neonatal and juvenile growth in rats.

Leptin, NPY, Melatonin and Zinc Levels in Experimental Hypothyroidism and Hyperthyroidism: The Relation to Zinc.

Since zinc mediates the effects of many hormones or is found in the structure of numerous hormone receptors, zinc deficiency leads to various functional impairments in the hormone balance. And also thyroid hormones have important activity on metabolism and feeding. NPY and leptin are affective on food intake and regulation of appetite. The present study is conducted to determine how zinc supplementation and deficiency affect thyroid hormones (free and total T3 and T4), melatonin, leptin, and NPY levels in thyroid dysfunction in rats. The experiment groups in the study were formed as follows: Control (C); Hypothyroidism (PTU); Hypothyroidism+Zinc (PTU+Zn); Hypothyroidism+Zinc deficient; Hyperthyroidism (H); Hyperthyroidism+Zinc (H+Zn); and Hyperthyroidism+Zinc deficient. Thyroid hormone parameters (FT3, FT4, TT3, and TT4) were found to be reduced in hypothyroidism groups and elevated in the hyperthyroidism groups. Melatonin values increased in hyperthyroidism and decreased in hypothyroidism. Leptin and NPY levels both increased in hypo- and hyperthyroidism. Zinc levels, on the other hand, decreased in hypothyroidism and increased in hyperthyroidism. Zinc supplementation, particularly when thyroid function is impaired, has been demonstrated to markedly prevent these changes.

Cardioprotective effects of lipoic acid, quercetin and resveratrol on oxidative stress related to thyroid hormone alterations in long-term obesity.

This study investigated possible mechanisms for cardioprotective effects of lipoic acid (LA), quercetin (Q) and resveratrol (R) on oxidative stress related to thyroid hormone alterations in long-term obesity. Female C57BL/6 mice were fed on high-fat diet (HFD), HFD+LA, HFD+R, HFD+Q and normal diet for 26weeks. Body weight, blood pressure, thyroid hormones, oxidative stress markers, angiotensin converting enzyme (ACE), nitric oxide synthase (NOS) and ion pump activities were measured, and expression of cardiac genes was analyzed by real-time polymerase chain reaction. HFD induced marked increase (P<.05) in body weight, blood pressure and oxidative stress, while plasma triidothyronine levels reduced. ACE activity increased (P<.05) in HFD mice (0.69±0.225U/mg protein) compared with controls (0.28±0.114U/mg protein), HFD+LA (0.231±0.02U/mg protein) and HFD+Q (0.182±0.096U/mg protein) at 26weeks. Moreover, Na(+)/K(+)-ATPase and Ca(2+)-ATPase activities increased in HFD mice whereas NOS reduced. A 1.5-fold increase in TRα1 and reduction in expression of the deiodinase iodothyronine DIO1, threonine protein kinase and NOS3 as well as up-regulation of AT1α, ACE, ATP1B1, GSK3ß and Cja1 genes also occurred in HFD mice. Conversely, LA, Q and R inhibited weight gain; reduced TRα1 expression as well as increased DIO1; reduced ACE activity and AT1α, ATP1B1 and Cja1 gene expression as well as inhibited GSK3ß; increased total antioxidant capacity, GSH and catalase activity; and reduced blood pressure. In conclusion, LA, resveratrol and quercetin supplementation reduces obesity thereby restoring plasma thyroid hormone levels and attenuating oxidative stress in the heart and thus may have therapeutic potential in heart diseases.

Longitudinal changes of endocrine and bone disease in adults with ß-thalassemia major receiving different iron chelators over 5 years.

In this study, we compared the long-term effects of different iron chelation regimens (deferoxamine, deferiprone, deferoxamine + deferiprone, and deferasirox) in preventing or reversing endocrinopathy (diabetes mellitus, hypothyroidism, or hypogonadism) and bone disease (measured through DEXA) in 165 adults with ß-thalassemia major (TM) (mean age 39.9 ± 8.3 years, 43 % males). After five consecutive years of therapy, patients on deferasirox had the highest decrease in the prevalence of any endocrinopathy compared to other chelators which either had no change (deferiprone and deferoxamine) or had an increase (deferoxamine + deferiprone), p = 0.015. This was attributed to a lower proportion of patients on deferasirox developing new-onset endocrinopathy and higher proportion showing reversal of disease, compared to other chelators. A serum ferritin level of >1300 ng/mL predicted the development of new endocrinopathy (p = 0.025) while a level of <200 ng/mL predicted reversal of existing endocrinopathy (p = 0.147). A significant increase in mean BMD T-score (p < 0.001) and a considerable decrease in osteoporosis prevalence were observed in patients receiving deferasirox but not other chelators. Iron chelation therapy with deferasirox has a role in the prevention of endocrinopathy and reversal of existing disease.

Selenium supplementation could restore euthyroidism in subclinical hypothyroid patients with autoimmune thyroiditis.

INTRIDUCTION: The thyroid is an organ with one of the highest selenium concentrations, containing many selenoproteins implicated in thyroid hormone metabolism. Treatment with levothyroxine has been recommended for all subclinical hypothyroid patients with TSH levels > 10 mU/L, whereas for those with TSH< 10 mU/L treatment remains controversial. AIM: A randomised controlled prospective study was performed to investigate the effects of Se treatment on patients with autoimmune thyroiditis and mild sub-clinical hypothyroidism (TSH < 10 mU/L). MATERIAL AND METHODS: A total of 196 patients with autoimmune thyroiditis were recruited in the study. Patients were assigned to receive (case) or not receive (control) an oral selenomethionine treatment. Cases received 83 mcg selenomethionine/day orally for four months. All the patient's charts were submitted to thyroid hormonal profile (TSH, fT4) and TPOAb evaluation upon enrolment and at the end of the study. RESULTS: In total 192 patients completed the study. Cases and controls were superimposable for age, gender, thyroid hormonal profile, and TPOAb levels. At the end of the study, 33/192 (17.2%) participants restored euthyroidism (Responders). Responders were significantly more frequent among Cases than Controls (30/96 [31.3%] vs. 3/96 [3.1%], p < 0.0001). CONCLUSION: Selenium supplementation could restore euthyroidism in one third of subclinical hypothyroidism patients with autoimmune thyroiditis. (Endokrynol Pol 2016; 67 (6): 567-571).

Low Population Selenium Status Is Associated With Increased Prevalence of Thyroid Disease.

CONTEXT: Epidemiological studies have supported the premise that an adequate selenium intake is essential for thyroid gland function. OBJECTIVE: The objective was to investigate whether the prevalence of thyroid disease differed in two areas that were similar, except for very different soil/crop selenium concentrations. DESIGN: Cross-sectional observational study. SETTING: The setting was two counties of Shaanxi Province, China, here defined as adequate- and low-selenium. PARTICIPANTS: A total of 6152 participants were selected by stratified cluster-sampling. MAIN OUTCOME MEASURES: Participants completed demographic and dietary questionnaires and underwent physical and thyroid ultrasound examinations. Serum samples were analyzed for thyroid function parameters and selenium concentration. Serum selenium was compared between different demographic, dietary, and lifestyle categories in the two counties. The relationship between selenium status, dietary factors, and pathological thyroid conditions was explored by logistic regression. RESULTS: Complete data sets were available from 3038 adequate-selenium participants and 3114 low-selenium participants in whom median (interquartile range) selenium concentrations differed almost 2-fold (103.6 [79.7, 135.9] vs 57.4 [39.4, 82.1] µg/L; P = .001). The prevalence of pathological thyroid conditions (hypothyroidism, subclinical hypothyroidism, autoimmune thyroiditis, and enlarged thyroid) was significantly lower in the adequate-selenium county than in the low-selenium county (18.0 vs 30.5%; P < .001). Higher serum selenium was associated with lower odds ratio (95% confidence interval) of autoimmune thyroiditis (0.47; 0.35, 0.65), subclinical hypothyroidism (0.68; 0.58, 0.93), hypothyroidism (0.75; 0.63, 0.90), and enlarged thyroid (0.75; 0.59, 0.97). CONCLUSIONS: Low selenium status is associated with increased risk of thyroid disease. Increased selenium intake may reduce the risk in areas of low selenium intake that exist not only in China but also in many other parts of the world.

Iodine deficiency and thyroid disorders.

Iodine deficiency early in life impairs cognition and growth, but iodine status is also a key determinant of thyroid disorders in adults. Severe iodine deficiency causes goitre and hypothyroidism because, despite an increase in thyroid activity to maximise iodine uptake and recycling in this setting, iodine concentrations are still too low to enable production of thyroid hormone. In mild-to-moderate iodine deficiency, increased thyroid activity can compensate for low iodine intake and maintain euthyroidism in most individuals, but at a price: chronic thyroid stimulation results in an increase in the prevalence of toxic nodular goitre and hyperthyroidism in populations. This high prevalence of nodular autonomy usually results in a further increase in the prevalence of hyperthyroidism if iodine intake is subsequently increased by salt iodisation. However, this increase is transient because iodine sufficiency normalises thyroid activity which, in the long term, reduces nodular autonomy. Increased iodine intake in an iodine-deficient population is associated with a small increase in the prevalence of subclinical hypothyroidism and thyroid autoimmunity; whether these increases are also transient is unclear. Variations in population iodine intake do not affect risk for Graves' disease or thyroid cancer, but correction of iodine deficiency might shift thyroid cancer subtypes toward less malignant forms. Thus, optimisation of population iodine intake is an important component of preventive health care to reduce the prevalence of thyroid disorders.

[The importance of selenium in Hashimoto's disease]. / Znaczenie selenu w leczeniu choroby Hashimoto.

The aim of this study was to present the current state of knowledge on the role of selenium in the treatment of Hashimoto's disease. In recent years, the number of cases of autoimmune Hashimoto's thyroiditis - a chronic disease that usually leads to hypothyroidism - has increased. Most patients have elevated levels of anti-TPO antibodies. The presence of these antibodies has an effect on subsequent thyroid damage. So far we have not developed an effective, standard therapy of this disease. However, more attention is being paid to the relationship between supplementation of selenium deficiency and inhibition of production of anti-TPO antibodies in patients with Hashimoto's thyroiditis. Therefore, selenium supplementation may be an effective option in the treatment of this disease.

Endocrine function and bone disease during long-term chelation therapy with deferasirox in patients with ß-thalassemia major.

Iron overload in ß-thalassemia major (TM) typically results in iron-induced cardiomyopathy, liver disease, and endocrine complications. We examined the incidence and progression of endocrine disorders (hypothyroidism, diabetes, hypoparathyroidism, hypogonadism), growth and pubertal delay, and bone metabolism disease during long-term deferasirox chelation therapy in a real clinical practice setting. We report a multicenter retrospective cohort study of 86 transfusion-dependent patients with TM treated with once daily deferasirox for a median duration of 6.5 years, up to 10 years. No deaths or new cases of hypothyroidism or diabetes occurred. The incidence of new endocrine complications was 7% (P = 0.338, for change of prevalence from baseline to end of study) and included hypogonadism (n = 5) and hypoparathyroidism (n = 1). Among patients with hypothyroidism or diabetes at baseline, no significant change in thyroid parameters or insulin requirements were observed, respectively. Mean lumbar spine bone mineral density increased significantly (P < 0.001) and the number of patients with lumbar spine osteoporosis significantly decreased (P = 0.022) irrespective of bisphosphonate therapy, hormonal replacement therapy, and calcium or vitamin D supplementation. There were no significant differences in the number of pediatric patients below the 5th centile for height between baseline and study completion. Six pregnancies occurred successfully, and four of them were spontaneous without ovarian stimulation. This is the first study evaluating endocrine function during the newest oral chelation therapy with deferasirox. A low rate of new endocrine disorders and a stabilization of those pre-exisisting was observed in a real clinical practice setting.