Associative relationships between vitamin D levels,immunological characteristics and thyroid volume in patients with hypothyroidism due to autoimmune thyroiditis

Abstract

Background. The leading factor of hypothyroidism in patients with autoimmune thyroiditis is destruction of the thyroid gland under the influence of the autoimmune process. Therefore, the essence of pathogenetic therapy for autoimmune thyroiditis is the prescription of immunomodulators. Understanding the features of autoimmune disorders in autoimmune thyroiditis will allow justifying the requirements for such drugs. Aim: to determine if there is an association between thyroid volume, vitamin D level, and immunological parameters in hypothyroidism due to autoimmune thyroiditis. Materials and methods. A comparative analysis of thyroid status in terms of thyroid-stimulating hormone and free thyroxine content, blood vitamin D levels and immune homeostasis indicators (CD3, CD4, CD8, CD16, CD22, thyroid pe­roxidase antibo­dies and thyroglobulin antibodies) was performed in 55 women with drug-compensated hypothyroidism due to autoimmune thyroiditis. The first group consisted of 29 women with autoimmune thyroi­ditis who for at least one year received indivi­dually selected thyroid replacement therapy, with thyroid volume of 11.05 ± 1.86 cm3, the second group — of 26 women, at least a year ago operated for benign thyroid nodules against the background of autoimmune thyroiditis, with thyroid volume of 4.26 ± 1.89 cm3 (p < 0.05 between groups). The control group included 12 women without autoimmune thyroiditis and hypothyroidism, thyroid volume was 8.7 ± 0.6 cm3. Results. While the thyroid status indicators in autoimmune thyroiditis patients were within the reference norms, the vitamin D level in the general group of women with autoimmune thyroidi­tis and hypothyroidism was significantly (p < 0.02) lower than in the control group, despite the fact that in the control group it corresponded to deficiency status (22.7 ng/ml), and against the background of autoimmune thyroiditis — to vitamin D deficiency (18.3 ng/ml). In patients with a smaller thyroid volume (group 2), the content of vitamin D was significantly (p < 0.05) lower than in group 1. Indicators of cellular immunity were within the re­ference standards, but the level of natural killers in group 2 was significantly (p < 0.05) lower. The levels of antithyroid antibo­dies in both groups were high, indicating the activity of the autoimmune process. Conclusions. In patients with hypothyroidism on the background of autoimmune thyroiditis in a state of drug compensation, smaller thyroid glands are associated with a more pronounced vitamin D deficiency. Thyroid volumes in patients with autoimmune thyroiditis are not associated with pronounced changes in cellular immunity, except for a decrease in the level of natural killers in smaller thyroid volume. The persistent activity of the autoimmune process in patients with hypothyroidism due to autoimmune thyroiditis against the background of prolonged and successful thyroid replacement therapy necessitates the addition of adequate immunomodulators to it, including vitamin D.