A beneficial levels of 25-hydroxyvitamin D for a decrease in thyrotropin receptor antibody (TRAB) in patients with Graves' disease: a real-world study.

Objective: This study aimed to determine whether a relationship exist between pre-therapy 25-hydroxyvitamin D levels and the remission/negative conversion rates of thyrotropin receptor antibody (TRAB) during treatment in patients with newly diagnosed Graves' disease (GD).

Methods: 171 patients were included from the Endocrinology Department of the First Affiliated Hospital of Fujian Medical University in March 2013 to April 2016. Ninety-five patients of them were diagnosed at our hospital but transferred to local hospitals for treatment. Seventy-six patients were followed and treated at our hospital with a median follow-up time of 11.03 (range 6-27) months. Patients were divided into 3 groups according to baseline 25-hydroxyvitamin D levels; <20 ng/mL (31,43.05%), 20-29 ng /mL (20,27.78%), and ≥ 30 ng/mL (20,29.17%). The TRAB remission rate and negative conversion rate was assessed among each group.

Results: There was a higher TSH and lower TRAB titer in the 20-29 ng/mL group at initial diagnosis. Cox regression analysis suggested that 20-29 ng/mL group had significantly higher remission rates [RR; 95% CI: 7.505 (1.401-40.201), 8.975 (2.759-29.196),6.853(2.206-21.285), respectively] and negative conversion rates [RR; 95% CI: 7.835 (1.468-41.804),7.189(1.393-37.092), 8.122(1.621-40.688)] at the 6-, 12-, and 24-month follow-up, respectively . The level of 25-hydroxyvitamin D at the time of initial diagnosis was not associated with the re-normal of free Triiodothyronine(FT3), free thyroxineIndex(FT4) or TSH levels during the follow-up.

Conclusion: Newly diagnosed GD patients with appropriate baseline 25-hydroxyvitamin D levels (20-29 ng/mL) are beneficial for the reduction of TRAB during antithyroid therapy.