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: Due to their numerous roles in several biological processes, zinc and selenium are the most commonly studied micronutrients in the elderly Therefore, we hypothesized that the polymorphisms in the genes that are responsible for the transport of zinc and selenium may have a genotype-dependent effect on the serum concentration of these micronutrients. The objective of this study was to determine the effects of SLC30A3 and SEP15 polymorphisms on zinc and selenium concentrations, respectively, in the serum. This cross-sectional study included 110 individuals who were at least 50 years of age. Serum micronutrient concentrations were determined by flame atomic absorption spectrophotometry (for zinc) and by atomic absorption spectrophotometry with a graphite furnace (for selenium). The SNP, rs73924411 and rs11126936 of the SLC30A3 gene and rs5859, rs5854, and rs561104 of the SEP15 gene, were examined by real-time PCR. Regarding rs11126936, the serum zinc concentration was lower in CC homozygotes (0.75 mg/L ± 0.31 mg/L) than in A carriers (0.89 mg/L ± 0.28 mg/L, p = 0.016). Concerning rs561104, the serum selenium concentration was higher in CC homozygotes (5.65 μg/dL ± 1.11 μg/dL) compared to T carriers (4.88 μg/dL ± 1.25 μg/dL, p = 0.044). Our results demonstrate the influence of SLC30A3 and SEP15 gene polymorphisms on the serum concentrations of zinc and selenium, respectively. The effects of these associations should be further investigated to help elucidate the modes of action of trace elements and to identify biomarkers which could ultimately define the optimal intake of these micronutrients at the molecular level. More research must be performed before the roles of these polymorphisms in the serum concentrations of zinc and selenium can be fully understood.Nutrition Research 08/2014; 34(9). DOI:10.1016/j.nutres.2014.08.009 · 2.59 Impact Factor
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ABSTRACT: Autoimmune thyroiditis (AIT) is one of the most common autoimmune diseases; genetic as well as environmental factors contribute to its pathogenesis. The thyroid is the organ with the highest selenium content per unit weight. Selenium status appears to have an impact on the development of thyroid pathologies. We investigated a possible difference of selenium serum levels as a marker of nutritional selenium supply between patients with AIT in central Lower Austria and a matched group of healthy persons living in the same region. Selenium serum levels in the patients with AIT were 98.0±15.6 μg/l. A significant difference to the matched group of normal persons, whose selenium serum levels were 103.2±12.4 μg/l, could not be detected by the t-test (p>0.05). We considered the serum selenium levels to be indicators of selenium supply (by alimentation). A serum level of 120-160 μg/l of selenium represents the normal range. According to this, most patients and control persons showed mild to moderate selenium deficiency (80-120 μg/l selenium). Although our data present slightly higher selenium levels in normal persons than in patients with AIT, this weak and statistically insignificant trend is not sufficient to support the conclusion of a link between inadequate selenium supply and autoimmune thyroid disease.Hormone and Metabolic Research 06/2014; 46(10). DOI:10.1055/s-0034-1377029 · 2.04 Impact Factor
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ABSTRACT: The therapeutic effect of selenium (Se) has already been proven in thyroid disease and thyroid associated ophthalmopathy (TAO). In spite of clear scientific proof of its benefits in TAO, there appears to be no clear agreement among the clinicians regarding its optimum dose, duration of the treatment, efficacy and safety to date. In this review, the author summarises the findings of 135 English language articles published on this subject over the past four decades from 1973 to 2013. The regulation and metabolism of thyroid hormones require a steady supply of Se and recent studies have revealed several possible mechanisms by which Se improves the severity of thyroid disease and TAO. These mechanisms include 1) inhibitory effect of HLA-DR molecule expression on thyrocytes; 2) profound reductions of thyroid stimulating hormone (TSH) receptor antibodies (TSHR-Ab) and TPO antibodies (TPO-Ab); 3) prevention of dysregulation of cell-mediated immunity and B cell function; 4) neutralising reactive oxygen species (ROS) and inhibition of redox control processes required for the activation, differentiation and action of lymphocytes, macrophages, neutrophils, natural killer cells involved in both acute and chronic orbital inflammation in TAO; 5) inhibition of expression of pro-inflammatory cytokines and 6) inhibition of prostaglandin and leukotriene synthesis. An increased oxidative stress has been observed in both acute and chronic phases of thyroid disease with raised tissue concentrations of ROS. The benefits of Se supplementation in individuals with TAO appear to be proportionate to the degree of systemic activity of the thyroid disease. The maximal benefit of Se supplementation is therefore seen in the subjects who are hyperthyroid. Restoration of euthyroidism is one of the main goals in the management of TAO and when anti-thyroid drugs are combined with Se, the patients with Graves' disease (GD) and autoimmune thyroiditis (AIT) achieved euthyroidism faster than those treated with anti-thyroid drugs alone. Se status of normal adult humans can vary widely and Se supplementation may confer benefit only if serum Se levels are insufficient. The author recommends that serum Se levels of patients with TAO to be assessed prior to and during Se supplementation at regular intervals to avoid potential iatrogenic chronic Se overdose.International Journal of Ophthalmology 04/2014; 7(2):365-375. DOI:10.3980/j.issn.2222-3959.2014.02.31 · 0.50 Impact Factor