Serum vitamin D level in patients with hashimato thyroiditis and evaluation of the change in serum vitamin D level after levothyroxine treatment

infiltration of the thyroid gland and is the most common cause of hypothyroidism in iodine sufficient areas. Recently, a relationship between vitamin D deficiency and autoimmune diseases has been reported. Due to the possible relationship of vitamin D in formation and progression of autoimmune diseases, our study was aimed to evaluate serum vitamin D level of the patients with Hashimato thyroiditis, which is an frequent autoimmune disease in community, and the change in serum vitamin D level after levothyroxine treatment.83 patients with Hashimato thyroiditis (30 eutyroid, 53 subclinical hypothyroidism) and 30 healthy control subjects were included into study. Hashimato thyroiditis was diagnosed with thyroid peroxidase and thyroglobuline antibody levels. Serum vitamin D levels were measured in patients and control group. Serum vitamin D levels were considered to be <20 ng/ml: deficiency, 20-30 ng/ml: insufficiency and >30 ng/ml: normal. Patients with subclinical hypothyroidism were treated with levothyroxine. Serum vitamin D levels were evaluated after becoming euthyroid.The mean vitamin D levels were found 10.5±6.5 ng/ml, 14.2±5.9 ng/ml, 18.8±6.5 ng/ml in euthyroid patients, in patients with subclinical hypothyroidism and in healthy control subjects, respectively. The difference between patients with Hashimato thyroiditis and the control subjects were statistically significant. Significant difference were also found between euthyroid group and subclinical group (p:0.045). Vitamin D deficiency was detected in 91.6% of patients with Hashimato thyroiditis and in 66.7% of the control group. Statistically significant increase of serum vitamin D levels in subclinical hypothyroidism group was found after levothyroxine treatment (from 14.2±5.9 ng/ml to 16.0±5.4 ng/ml, p:0.000)They were thyroid dysfunction in patients with Hashimato thyroiditis and serum vitamin D levels were significantly deficient in this cases. This condition considered that relationship between vitamin D deficiency and progression of Hashimato thyroiditis. Further studies are needed for the role of vitamin D supplementation in formation and progression of autoimmune thyroid disease.Key Words: Hashimato thyroiditis, Vitamin D, Hypothyroidism