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Background: Sri Lanka introduced universal salt iodization (USI) in 1995 after which we demonstrated a high thyroglobulin antibody (TgAb) prevalence in 1998. However, it is unclear whether thyroid autoimmunity persists in the long term in populations exposed to sustained USI and whether such populations have an excess of thyroid dysfunction. We evaluated the prevalence of thyroid autoantibodies and dysfunction in Sri Lankan children and adolescents after more than two decades of sustained USI. Methods: We selected 10- to 18-year-old subjects of both sexes (randomized cluster sampling) from all 9 provinces of Sri Lanka in this cross-sectional study. Blood, urine, and anthropometric data were collected and thyroid ultrasound scans were performed. Validated statistical methods were used to derive local population-specific reference ranges for all thyroid parameters. We also measured urine iodine concentration (UIC), salt, and water iodine concentrations. Results: Blood and urine samples from 2507 and 2473 subjects respectively, and ultrasound scans from 882 subjects were analyzed. Population-derived upper limits for thyroid peroxidase antibody (TPOAb) and TgAb, and reference ranges for triiodothyronine, thyroxine, and thyrotropin (total and age-year-related groups) were significantly different from manufacturer's reference ranges. Using these derived ranges, the prevalence of TPOAb was 10.3% and TgAb was 6.4%. Of the TPOAb-positive subjects, TPOAb were of low concentration in 66.2% (1-3 times the upper limit of the reference range [ULRR]) and showed the strongest association with subclinical hypothyroidism (SCH) at the highest concentrations (>4 ULRR). The prevalence of SCH was 3%. Median UIC (interquartile range) was 138.5 μg/L (79.4-219.0) with regional variability, and median thyroglobulin was 8.3 ng/mL (4.1-13.5). Goiter prevalence was 0.6% and 1.93% (thyroid volume compared to age and body surface area, respectively). Salt and water iodine concentrations were satisfactory. Conclusions: Sri Lanka has safely and effectively implemented USI with good sources of iodine, leading to sustained iodine sufficiency over more than two decades. The early postiodization TgAb surge (42.1%) has settled (6.4%), and despite a persistently high TPOAb prevalence (10.3%), SCH prevalence remains low (3%). Further studies should be undertaken to monitor thyroid autoimmune dysfunction in Sri Lankan children, using age-specific, population-derived reference ranges.

The studies on the increasing incidence of thyroid abnormalities are scarce. The aim of this current study was to ascertain the effects of geographical region on thyroid abnormalities under the context of universal salt iodization (USI). We randomly selected 1255 participants residing in inland and 1248 in coast, with the determination of urinary iodine concentration (UIC) and functional and morphological abnormalities of thyroid gland. The median UIC was significantly higher for the inland participants (188.5 μg/L) than the coastal participants (128.5 μg/L; p < 0.001), indicating iodine sufficiency in both populations according to the recommended assessment criteria by the World Health Organization. However, the spectrum of thyroid abnormalities varied between regions, with hypothyroidism prevalent in inland and thyroid nodules in coast. The associations between region and thyroid abnormalities via binary logistic regression models showed that the coastal participants were at a higher risk of total thyroid abnormalities than those from the inland (OR 1.216, 95% CI 1.020-1.449), after the adjustment of ten confounders (demographical characteristics, smoking status, metabolism syndrome, and hyperuricemia). These results indicated that further investigations of the adverse effects of hypothyroidism and thyroid nodules on health burden is urgently needed to sustain USI program.

In animals, long-term feeding with peanut (Arachis hypogaea) seed coats causes hypertrophy and hyperplasia of the thyroid gland. However, to date there have been no detailed studies. Here, we explored the thyroidal effects of dietary peanut seed coats (PSC) in rats. The PSC has high levels of pro-goitrogenic substances including phenolic and other cyanogenic constituents. The PSC was mixed with a standard diet and fed to rats for 30 and 60 days, respectively. Animals fed with the PSC-supplemented diet showed a significant increase in urinary excretion of thiocyanate and iodine, thyroid enlargement, and hypertrophy and/or hyperplasia of thyroid follicles. In addition, there was inhibition of thyroid peroxidase (TPO) activity, 5'-deiodinase-I (DIO1) activity, and (Na+-K+)-ATPase activity in the experimental groups of rats as compared to controls. Furthermore, the PSC fed animals exhibited decreased serum circulating total T4 and T3 levels, severe in the group treated for longer duration. These data indicate that PSC could be a novel disruptor of thyroid function, due to synergistic actions of phenolic as well as cyanogenic constituents.

Objective: Thyroid dysfunction is associated with impaired cognitive development. Perchlorate decreases thyroidal iodine uptake, potentially reducing thyroid hormone production. It is unclear whether perchlorate exposure in early life affects neurodevelopment., Design: Historical cohort analysis., Patients: From 2002 to 2006, 21,846 women at gestational age <16 weeks recruited from antenatal clinics in Cardiff, UK and Turin, Italy were enrolled in the Controlled Antenatal Thyroid Screening Study (CATS). We undertook a retrospective analysis of 487 mother-child pairs in mothers who were hypothyroid/hypothyroxinemic during pregnancy and analyzed whether first trimester maternal perchlorate levels in the highest 10% of the study population were associated with increased odds of offspring IQ being in the lowest 10% at 3 years of age., Main Outcome Measures: Maternal urinary perchlorate, offspring IQ., Results: Urine perchlorate was detectable in all women (median 2.58 μg/L); iodine levels were low (median 72 μg/L). Maternal perchlorate levels in the highest 10% of the population increased the odds of offspring IQ being in the lowest 10% OR = 3.14 (95% CI 1.38, 7.13) P = .006 with a greater negative impact observed on verbal OR = 3.14 (95% CI 1.42, 6.90) P = .005 than performance IQ. Maternal levothyroxine therapy did not reduce the negative impact of perchlorate on offspring IQ., Conclusions: This is the first study using individual-level patient data to study maternal perchlorate exposure and offspring neurodevelopment and suggests that high-end maternal perchlorate levels in hypothyroid/hypothyroxinemic pregnant women have an adverse effect on offspring cognitive development, not affected by maternal levothyroxine therapy. These results require replication in additional studies, including in the euthyroid population.

Objective: To study the associations between intakes of iodine and water chemicals and the thyroid gland status of schoolchildren living in the coastal city of Port Sudan., Design: In our previous nationwide study on goitre, it was observed that the prevalence of goitre was high in Port Sudan city despite high urinary iodine excretion. A cross-sectional study including schoolchildren aged 6–12 years was designed. Measurements determined the prevalence of goitre, urinary iodine concentration and thiocyanate secretion in casual urine samples, serum levels of thyroxine, triiodothyronine, thyroid-stimulating hormone and thyroglobulin, as well as the levels of Cl⁻, F⁻, Ca²⁺, Mg²⁺ and total hardness of drinking water., Subjects: Schoolchildren (n 654) aged 6–12 years., Setting: Port Sudan city is located at the western bank of the Red Sea. The city is surrounded by a mountainous area known as the Red Sea Hills. It is the main sea port in the Sudan, inhabited by ethnically and socio-economically heterogeneous populations., Results: The prevalence of goitre in Port Sudan was 34.86% while the median urinary iodine concentration was 46,4μg/dl. Out of thirty-one pupils from Port Sudan, twenty-four (77.42 %) were found to have urinary iodine concentration greater than 30μg/dl and twelve (38.71 %) had different degrees of biochemical hypothyroidism. Excessive concentrations of Cl⁻, Ca²⁺, Mg²⁺ and water hardness (369.2, 116.48, 60.21 and 539.0mg/l, respectively) were detected in drinking water samples collected from Port Sudan that exceeded levels permitted by the WHO., Conclusions: The coastal city of Port Sudan is a goitre-endemic area. In contrast to other Sudanese cities in which endemic goitre is related to iodine deficiency, goitre in Port Sudan is associated with iodine excess. Water chemicals seemed to have no effects on thyroid status.

Nitrate is a wide spread contaminant of ground and surface water. The source of nitrate in the ground water may be from run off or seepage from fertilized soil, municipal or industrial waste water, land fills, septic system, urban drainage or decaying plants. Human and animal systems are affected severely on nitrate exposure. The study was to investigate the effect of dietary nitrate exposure on the thyroid status along with the state of iodine nutrition. Rats were fed diet containing 3% potassium nitrate (KNO3) for 4 weeks and then thyroid status was evaluated by thyroid gland weight, urinary iodine excretion pattern, thyroid peroxidase (TPO) activity, serum levels of total thyroxine (T4), triiodothyronine (T3) and thyroid stimulating hormone (TSH) concentrations. In nitrate treated animals, the weight of thyroid gland was increased significantly (P<0.001) while thyroid peroxidase activity (P<0.01), serum T4 (P<0.01) and serum T3 levels (P<0.001) were reduced; but serum TSH level was increased (P<0.001) along with slightly elevated iodine excretion level (P<0.001) in comparison to control animals. The overall results indicated the development of a relative state of functional hypothyroidism with enlarged thyroid after nitrate exposure. This study can explain a part for the persistence of residual goitre in the post-salt iodization phase.

Iodine is an essential element with unique role in organism: it is indispensable component of thyroid hormones. After binding with specific nuclear receptor, T3/T4 induce transcription of genetic code via mRNA and regulate proteosynthesis in most tissues. Thyroid hormones regulate rate of metabolic processes and consequently development of organism. Czech Republic was in past typical region with moderate to severe iodine deficiency. Therefore epidemiological survey was started in randomly selected samples of peoples. Thereafter a complex program of improving iodine supply was realized. Prompt effects of this changes were recorded, namely increase of ioduria and decrease of thyroid volume. Essential trace element selenium has a fundamental importance to the cell and body metabolism regulation by thyroid hormones. Activities of selenoenzymes deiodinases lead to the activation of prohormone T4 to active hormone T3 and the inactivation of T3 and of T4, as well. There is unfortunately moderate to mild Se deficit in the CR. Average serum Se concentrations for the populations from 6 to 65 years are in the regions of the CR between 42 and 62 micrograms/l and urine Se values are between 8 and 15 micrograms/l. We have found statistically significant correlations among indexes of selenium status and indexes of thyroid hormone metabolism and function. Especially dangerous are concomitant deficiencies of both key elements for thyroid hormone metabolism--I and Se--from the point of thyroid hormone regulative functions.

Objective: Previously we reported 3,3'-diiodothyronine sulfate-like material (compound W) in maternal serum, and studies suggest that compound W is derived from thyroid hormones of fetal origin. In this study we characterized gestational changes of urinary compound W concentrations to correlate with changes in serum concentrations., Study Design: Urinary samples were collected from 94 women at various gestational ages ranging from 3 to 40 weeks. Urinary compound W was first identified biochemically. The concentrations of compound W (adjusted for creatinine levels) were assessed by a 3,3'-diiodothyronine sulfate radioimmunoassay in ethanol extracts of urine samples., Results: Compound W increased to 88 +/- 1.4 pmol (of 3,3'-diiodothyronine sulfate equivalent)/mmol creatinine in urinary samples obtained from 26 women in the first trimester of pregnancy compared with 40 +/- 6.9 pmol/mmol creatinine in 10 nonpregnant women. Excretion of compound W increased further during the second and third trimesters: 171 +/- 17 (n = 18) and 434 +/- 26 (n = 50) respectively. In contrast, urinary 3,3',5-triiodothyronine sulfate concentrations measured by radioimmunoassay were similar during pregnancy to values in nonpregnant women., Conclusions: Urinary compound W concentrations increase with the progression of normal pregnancy and correlate with the increase in serum levels. Random spot urine compound W concentrations, adjusted for creatinine levels, may be used in place of serum levels in conditions in which obtaining serum samples may be technically difficult, especially during population screening.

In order to assess the Japanese dietary iodine intake, we examined the urinary iodine excretion of those on an ordinary Japanese diet chosen at random and observed whether the thyroid function might affect the amounts of urinary iodine excretion. The subjects consisted of cases of untreated hypothyroidism and chronic thyroiditis (CT) and euthyroid controls who were healthy people or had non-thyroidal disorders such as diabetes mellitus or hypertension. Eight cases of hypothyroidism were composed of 3 cases of secondary hypothyroidism with empty sella syndrome and 5 cases of primary hypothyroidism and 32 patients with CT have been maintained in euthyroid states with T4 medication. We selected 32 cases of sex and age-matched healthy people as controls. The mean levels of excreted urinary iodine were 465.6 micrograms/day in the healthy controls and 471.8 micrograms/day in patients with CT, respectively. Urinary iodine excretion was significantly correlated to serum inorganic iodide in both controls and CT patients, of which correlation coefficients were +0.35 and +0.5, respectively. Urinary iodine and serum inorganic iodide ratios (U/S) in hypothyroidism were significantly (p less than 0.05) depressed compared with those in CT. The present study indicated that recent Japanese dietary iodine intake was estimated to be approximately 470 micrograms/day and that the urinary iodine excretion would be influenced not only by iodine intake but also by thyroid function.

Thyroid hormones affect both renal morphology and function. They are required for kidney growth and development, and thyroid deficiency results in decreased renal plasma flow and glomerular filtration rate and in impaired urinary concentration and dilution. Thyroid hormones also influence membrane transport and electrolyte metabolism, and alterations in mineral metabolism in hyperthyroidism frequently cause calcium nephropathy which affects renal function adversely. The kidney plays an important role in the peripheral metabolism of iodine and thyroid hormones, and thyroid function is altered in certain kidney diseases, particularly chronic renal failure. The pathogenesis of these alterations is currently under active investigation.