Endocrine Abstracts

Vitamin D has immunomodulatory features and its deficiency is associated with the development of autoimmune diseases. The relation between vitamin D deficiency and autoimmune thyroiditis has not been investigated much. In the present study, our aim was to study the relation between vitamin D therapy and autoimmune thyroiditis.

Fifty-four patients having newly diagnosed Hashimoto thyroiditis (HT) and vitamin D deficiency but requiring no thyroid hormone replacement therapy at the time of enrolment to the study were included in the study. Once every 3 months, the patients received i.m. cholecalciferol injection (300.000 IU). During diagnosis and at the end of vitamin D therapy, thyroid functions, thyroid antibodies, 25(OH)D₃, PTH, Ca, P and ALP levels were in each patient while TNF-α, IL6 and IL1b levels were measured in only 43 patients.

When pre-therapy and post-therapy levels of FT₄, TSH, antiTPO, antiTG, PTH and ALP were compared, there was a significant difference (P<0.05). While there was a significant increase in FT₄ levels after the therapy, the decrease in TSH, antiTPO, antiTG, PTH and ALP levels was significant. There was no significant difference in terms of FT3, Ca, P, TNF-α, IL6 and IL1b. The was no correlation between pre-therapy and post-therapy vitamin D levels and FT₃, FT₄, TSH, antiTPO, antiTG, PTH, Ca, P, ALP, TNF-α, IL6 and IL1b.

An increase in FT₄ level and a decrease in TSH, antiTPO and antiTG levels after a 3 months vitamin D therapy in patients having HT and vitamin D deficiency but requiring no LT₄ therapy suggest that HT may have a positive effect on thyroid antigenicity and function. Autoimmune thyroiditis frequently progresses into subclinical hypothyroidism and overt hypothyroidism after euthyroid phase. Such a progress can be slowed down or prevented by vitamin D therapy in HT patients having vitamin D deficiency.

Key words: Autoimmune thyroid diseases, Hashimoto’s thyroiditis, Vitamin D deficiency.