Abstract

Back ground: Autoimmune diseases are increasing in prevalence due to the penetration of negative environmental conditions and endocrine disruptors into daily life. With the development of etiological factors there is also an uprise in childhood autoimmune thyroid diseases. Selenium (Se) is an essential element to the human body that helps regulate anti-inflammatory, immune-regulatory, antioxidant and endocrine functions both as a structural component and as a cofactor. It joins the molecular formation of the enzyme glutathione peroxidase which plays an active role in thyroid metabolism.

Aim: To investigate the role of selenium deficiency in the etiology of autoimmune thy-roiditis and the effect of selenium replacement therapy especially in early stage diseases.

Study design: Case control study

Materials and Method: The studies included were 54 subclinical hypothyroidism cases. After the detailed history of the all cases, anthropometric measurements, physical examination, biochemistry, hormonal (thyroid hormone, antibodies, spot iodine in urine, serum selenium levels…) bone age and thyroid ultrasonography were performed. Subclinical hypothyroidism diagnoses were made for cases with elevated TSH levels, normal sT4 levels (prepubertal TSH: 0.6-5.5 mIU/L, sT4: 0.8-2.2 ng/mL; pubertal TSH: 0.5-4.8 mIU/L, ST4: 0.8-2.3 ng/mL). After determining the etiology of subclinical hypothyroidism cases were categorized into two groups; as the first group autoimmune thyroiditis (n: 28) and second group without autoimmune thyroiditis (n: 26). Thyroid function tests were analyzed chemiluminescence immunoassay, Se levels was analyzed atomic absorption spectrophotometer method. Cases with Se deficiency were given oral selenium replacement therapy (50 mcg/day).

Results: All of the cases, %61.1 were girls and %38.9 was boys; %53.1 was prepubertal and %46.9 was pubertal. A total of %18.5 cases were obese, %9.25 was overweight, and %18.5 cases were malnourished. Mean selenium level was 64.4±14.19 g/dl in Group I and 100.7±20.1 g/dl in Group II, there was a remarkably significant difference between the two groups. Group I had notably low Se levels in contrast to high TSH, anti-TG and anti-TPO levels. There was a negative correlation between Se deficiency and elevated anti-TPO levels. Group II showed positive correlation between serum Se and fT4. Statistically significant regression was observed in anti-TG (p: 0.006) and anti-TPO (p: 0.00) levels 3 months after oral selenium replacement therapy.

Conclusion: Our study suggests that after oral Se treatment, progression of autoimmunity were diminished. Hence that selenium replacement might be useful in childhood and adolescents especially (with low titer antibody elevation) early stages autoimmune thyroiditis.