Endocrine Abstracts

Background: Hypovitaminosis D represents at present a worldwide public health problem. Recent studies have demonstrated the pleiotropic effects of vitamin D, in addition to its known actions on calcium-phosphorus metabolism. Among the several non-skeletal effects, a potential anti-inflammatory and immunomodulatory action has been suggested. Vitamin D deficiency has been reported in several chronic conditions associated with increased inflammation and deregulation of the immune system, such as Hashimoto’s thyroiditis, and may act as a cofactor in the etiopathogenesis of these clinical conditions. On this basis, correction of hypovitaminosis D through therapeutic supplementation could have an impact on these pathologies.

Aim: to evaluate, in patients with Hashimoto’s thyroiditis and hypovitaminosis D, the impact of cholecalciferol therapy on the parameters of calcium-phosphorus metabolism, antibody titer and indices of thyroid function.

Matherials and methods: a sample of 42 patients (6 men and 36 women) affected by hypovitaminosis D and Hashimoto’s thyroiditis was recruited; oral cholecalciferol therapy was administered at a dosage of 100.000 IU, once a month during a meal. Before initiation (T0) and one week after the fourth dose of cholecalciferol (T1), the following parameters were evaluated: TSH, FT3, FT4, 25-OH-cholecalciferol, PTH, Calcium, Phosphorus, Creatinine, AbTg, AbTPO.

Results: a linear mixed-effects analysis was performed using R software (version 4.1.1). No significant changes in antibody titer or thyroid hormones were observed following cholecalciferol treatment. There was a statistically significant increase in serum 25-OH cholecalciferol after supplementation, with no significant changes in the other parameters. There was no significant reduction in PTH, although a downward trend was shown, after 4 months of therapy.

Conclusions: our results show that Vitamin D replacement therapy with cholecalciferol, in Hashimoto thyroiditis patients, does not affect the inflammatory nor the functional thyroid status, despite the fact that supplementation is effective in correcting hypovitaminosis D. No significant change in the antithyroid antibody titer emerged. Further studies are needed to investigate the immunoregulatory functions of vitamin D and its effects on thyroid autoimmunity.