Vitamin D deficiency and autoimmune thyroid disease: relationship and correction (literature review and clinical cases)

Abstract

Numerous studies by various authors indicate an association between vitamin D and autoimmune thyroid diseases. Most authors point to a correlation between lower vitamin D levels and an increased risk of developing the disease and/or higher antibody titers. After the onset of autoimmune thyroid disease, the existing vitamin D deficiency creates a vicious circle, exacerbating the deficiency. In real clinical practice, it is important to correct vitamin D deficiency/insufficiency in persons with autoimmune thyroid diseases. The approach is to achieve a level of 25(OH)D within the reference ranges proposed by international guidelines. Vitamin D deficiency is an integral part of the pathogenesis of autoimmune thyroid diseases. Because vitamin D administration reduces antithyroid antibody titers in patients with autoimmune thyroid disea­ses, vitamin D supplements are recommended for the treatment of these diseases, especially in vitamin D deficiency. Both in Graves’ disease and autoimmune thyroiditis with subclinical hypothyroi­dism, the initial dose of cholecalciferol is 4,000 IU per day for three months, followed by control of the content of 25(OH)D in the serum. When the level of vitamin D reaches 30–50 ng/ml, it is recommended to continue taking cholecalciferol in a daily dose of 2,000 IU for three months. It is desirable to conduct such courses at least twice a year. As the positive effect of the optimal level of 25(OH)D in the serum of both children and adults has been proven to date, it is advisable to maintain it for a healthy population in the range of 30–50 ng/ml in accordance with the guidelines for Central European countries. There are two cases from real clinical practice, in which a positive effect was achieved after additional administration of cholecalciferol to patients with autoimmune thyroid diseases.