Selenium status, thyroid volume, and multiple nodule formation in an area with mild iodine deficiency
ABSTRACT The objective was to study the associations between serum selenium concentration and thyroid volume, as well as the association between serum selenium concentration and risk for an enlarged thyroid gland in an area with mild iodine deficiency before and after iodine fortification was introduced. Another objective was to examine the association between serum selenium concentration and prevalence of thyroid nodules.
We studied participants of two similar cross-sectional studies carried out before (1997-1998, n=405) and after (2004-2005, n=400) introduction of iodine fortification. Serum selenium concentration and urinary iodine were measured, and the thyroid gland was examined by ultrasonography in the same subjects. Associations between serum selenium concentration and thyroid parameters were examined in multiple linear regression models or logistic regression models.
Serum selenium concentration was found to be significantly, negatively associated with thyroid volume (P=0.006), and a low selenium status significantly increased the risk for thyroid enlargement (P=0.007). Furthermore, low serum selenium status had a tendency to increase the risk for development of multiple nodules (P=0.087).
Low serum selenium concentration was associated with a larger thyroid volume and a higher prevalence of thyroid enlargement.
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ABSTRACT: To analyze the impact of selenium supplementation on serum antiTPO levels and thyroid echogenicity in patients with CAT, evaluating the response in subgroups with different GPx1 genotypes. CAT patients (n = 55) with positive antiTPO were randomized to selenomethionine (SeMet) 200 μg daily (n = 28) or placebo (n = 27) for 3 months. Assessments included GPx1 genotyping at baseline and serum levels of plasma selenium, erythrocyte GPx1 activity, antiTPO and thyroid echogenicity at baseline, and 3 and 6 months. In the SeMet group, the increase in plasma levels of selenium and erythrocyte GPx1 activity was similar among patients with different GPx1 genotypes. In the overall cohort, patients randomized to SeMet showed a 5 % decrease in antiTPO levels at 3 months (p = non-significant) and 20 % at 6 months (p < 0.001 versus 3 months). In contrast, patients in the placebo group did not show significant changes in antiTPO levels at any time point. Subgroup analysis showed that patients with different GPx1 genotypes presented comparable responses in antiTPO levels and echogenicity index to SeMet. Selenium supplementation decreased serum antiTPO levels in CAT patients, with similar response among patients with different GPx1 genotypes.Journal of endocrinological investigation 04/2015; DOI:10.1007/s40618-015-0285-8 · 1.55 Impact Factor
Article: Thyroid disorders.[Show abstract] [Hide abstract]
ABSTRACT: All forms of thyroid diseases are much more frequently observed in women than men, although the reasons are still not completely elucidated.Hyperthyroidism is defined by elevated circulating free thyroid hormones. The prevalence is about 2 % in women and 0.2 % in men. The most frequent causes are various forms of thyroid autonomy in elderly women and Graves' disease, which occurs mostly in younger women.Hypothyroidism is defined by a lack of thyroid hormones. It is a common endocrine disorder caused by autoimmune thyroiditis (Hashimoto thyroiditis), iodine deficiency or following surgery or radioiodine therapy. Thyroxine requirements depend on fat-free mass and are, therefore, somewhat higher in males who are more often undersubstituted. In pregnancy lower TSH-reference ranges have to be considered and thyroid function should be monitored throughout pregnancy to avoid harm to the foetus caused by maternal thyroid dysfunctions. If overtreated women more often feature fractures, whereas males more often develop atrial fibrillation.Handbook of experimental pharmacology 01/2012; DOI:10.1007/978-3-642-30726-3_17
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ABSTRACT: Selenium (Se) is a necessary element for the biosynthesis of thyroid hormones. We investigated the relationship between selenium status, thyroid volume, and goiter in a cross-sectional study in an iodine-sufficient area. We selected residents of Chengdu (over 18 years old and living in the city for more than 5 years) using a stratified cluster sampling technique. Fifteen hundred subjects were selected for the study, which involved a questionnaire survey, physical examination, thyroid ultrasound, serum thyroid function test, and determination of serum selenium level. Thyroid volume was calculated from the thickness, width, length, and a corrective factor for each lobe. Ultimately, 1,205 subjects completed the investigation and were included in our study. Additionally, 80 school-age children were selected to provide urine samples for urinary iodine analysis. We analyzed the data using appropriate nonparametric and parametric statistical tests. The median urinary iodine value was 184 mug/L in school-age children, indicating iodine sufficiency. The median serum selenium level of the 1,205 subjects was 52.63 (interquartile range [IQR] : 40.40-67.00) mug/L. The median thyroid volume was 9.93 (IQR: 7.71-12.57) mL; both log-transformed serum selenium and log-transformed thyroid volume were Gaussian distributions (P = .638 and P = .046, respectively). The prevalences of goiter and thyroid nodules were 8.8% and 18.6%. The prevalences of positive thyroid autoantibodies, thyroperoxidase autoantibodies and thyroglobulin autoantibodies were 16.7%, 12.0%, and 11.1%, respectively. In the general linear regression model, there were positive associations between serum selenium and age, and body mass index. We found no association between serum selenium and thyroid-stimulating hormone. In simple linear regression analyses, we found no association between thyroid volume and serum selenium. There were no significant differences in serum selenium between persons with or without goiter. Serum selenium was not a risk factor for goiter. In our study population, serum selenium was neither associated with thyroid volume nor with goiter in an iodine-sufficient area. More studies should be conducted by following non-goitrous persons over time and monitoring their selenium status.BMC Public Health 12/2013; 13(1):1153. DOI:10.1186/1471-2458-13-1153 · 2.32 Impact Factor