Effect of Vitamin D Supplementation on Thyroid Autoimmunity among Subjects of Autoimmune Thyroid Disease in a Coastal Province of India: A Randomized Open-label Trial.

Objective: Hashimoto's thyroiditis (HT) is a variant of autoimmune thyroid disorders (AITD) which has been associated with vitamin D (vit-D) deficiency. However, whether vit-D supplementation is linked to reduction of thyroid autoantibodies and improvement of thyroid function is not well characterized. The present study was planned to evaluate the effect of vit-D supplementation on possible improvement of thyroid autoantibody titer and thyroid hormone profile in patients with AITD subjects.

Methods: Twenty-three patients of HT were given weekly supplementation of 60,000 IU vit-D for 8 weeks followed by once a month for another 4 months. After 6 months of vit-D supplementation, thyroid autoantibody titer (TPO antibody) and thyroid hormone profile was rechecked.

Results: Mean serum vit-D was increased significantly from 15.33 ± 5.71 to 41.22 ± 12.24 ng/mL (normal levels) after supplementation. There was significant increase in thyroid autoantibody titre (from 746.8 ± 332.2 to 954.1 ±4 59.8 IU/ml; P = 0.006) and TSH level (7.23 ± 3.16 to 3.04 ± 2.62 (mIU/L); P = 0.01) following 6 months of vit-D supplementation.

Conclusion: Vitamin-D levels were low in AITD patients in eastern India and, its supplementation in HT patients increased thyroid antibody titer and there was significant reduction in serum TSH and increased in free T4.