Effect of vitamin D supplementation on TSH levels in euthyroid subjects with autoimmune thyroiditis

• Published in: Endocrine Vol. 70; no. 1; pp. 85 - 91
• Main Authors: Villa, Alice, Corsello, Andrea, Cintoni, Marco, Papi, Giampaolo, Pontecorvi, Alfredo, Corsello, Salvatore Maria, Paragliola, Rosa Maria
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.10.2020; Springer Nature B.V
• Subjects: 25-Hydroxyvitamin D; Diabetes; Diagnosis; Endocrinology; Humanities and Social Sciences; Internal Medicine; Medicine; Medicine & Public Health; multidisciplinary; Original Article; Science; Supplements; Thyroid; Thyroid gland; Thyroid-stimulating hormone; Thyroiditis; Vitamin D; Vitamin deficiency; Hashimoto’s thyroiditis; Vitamin D; Thyroid function; Hypovitaminosis D
• ISSN: 1355-008X; 1559-0100; 1559-0100
• DOI: 10.1007/s12020-020-02274-9

Purpose The impact of vitamin D supplementation on thyroid function is not clear and the relationship between hypovitaminosis D and autoimmune thyroiditis (ATD) incidence and evolution is still a matter of debate. The aim of this study was to retrospectively evaluate the impact of vitamin D supplementation on thyroid function in subjects with and without ATD. Methods One hundred and ninety-eight euthyroid subjects, with diagnosis of “hypovitaminosis D” (<30 ng/mL) who had been taking supplementation therapy with cholecalciferol for different time periods, were included. They were divided in two groups according to the previous diagnosis of ATD: “ATD-neg” group including subjects without ATD [ n  = 103 (52%)]; “ATD-pos” group including subjects with a confirmed diagnosis of ATD [ n  = 95 (48%)]. For both groups, we considered TSH and 25 hydroxyvitamin D (25OHD) levels before (T0) and after (T1) cholecalciferol supplementation. We also considered the treatment duration and the monthly dose of cholecalciferol expressed as IU/month. Results In hypovitaminosis D subjects with ATD, TSH levels significantly decreased after therapy with cholecalciferol 100.000 IU/month [mean ± SD, TSH at T0: 2.67 ± 1.21 vs. TSH at T1: 2.28 ± 0.86, p  = 0.028]. No significant TSH variation was observed in ATD-neg group, irrespective of treatment dose and duration. As expected, 25OHD levels significantly improved with all monthly doses and especially in the group receiving 100.000 IU/month. Conclusions Cholecalciferol supplementation improved thyroid function in euthyroid ATD-pos subjects affected with severe hypovitaminosis D. In particular, a significant reduction in TSH levels was observed in subjects with very low baseline 25OHD levels, after taking high monthly doses of cholecalciferol.