Effect of Vitamin D deficiency treatment on thyroid function and autoimmunity markers in Hashimoto's thyroiditis: A double-blind randomized placebo-controlled clinical trial

Abstract

Background: The link between autoimmune thyroid diseases and Vitamin D deficiency has been reported. However, there are controversies in this regard. We conducted a double-blind randomized placebo-controlled clinical trial to investigate the effect of Vitamin D deficiency treatment on thyroid function and autoimmunity marker (thyroid peroxidase antibody TPO-Ab) in patients with Hashimoto's thyroiditis. Materials and Methods: Fifty-six patients with Hashimoto's thyroiditis and Vitamin D deficiency (25-hydroxyvitamin D level <= 20 ng/mL) were randomly allocated into two groups to receive Vitamin D (50000 IU/week, orally) or placebo for 12 weeks, as Vitamin D-treated (n = 30) and control (n = 26) groups, respectively. TPO-Ab, thyroid-stimulating hormone (TSH), parathormone, calcium, albumin, and creatinine concentrations were compared before and after trial between and within groups. The data were presented as mean (standard error SE) and analyzed by appropriate tests. Results: Mean (SE) of Vitamin D was increased in Vitamin D-treated group (45.5 1.8 ng/mL vs. 12.7 0.7 ng/mL, P = 0.01). Mean (SE) of TPO-Ab did not significantly change in both groups (734 102.93 IU/mL vs. 820.25 98.92 IU/mL, P = 0.14 in Vitamin D-treated and 750.03 108.7 IU/mL vs. 838.07 99.4 IU/mL in placebo-treated group, P = 0.15). Mean (SE) of TSH was not changed in both groups after trial, P = 0.4 and P = 0.15 for Vitamin D-treated and control groups, respectively. No significant difference was observed between two study groups in none studied variables (P > 0.05). Conclusion: Vitamin D treatment in Vitamin D deficient patients with Hashimoto's thyroiditis could not have significant effect on thyroid function and autoimmunity.