Effect of Vitamin D Supplementation on Muscle Function in Patients With I131-Induced Hypothyroidism: A Pilot Randomized Trial

Abstract

Background There is a lack of data regarding the effect of vitamin D supplements in I131-induced hypothyroidism patients. The primary aim of this study was to investigate the effect of vitamin D supplements on muscle function, and the secondary aim was to observe the effect on body composition, insulin resistance, and quality of life (QOL) in I131-induced hypothyroidism patients. Methods In this pilot randomized, placebo-controlled trial, I131-induced hypothyroidism patients with a stable dose of levothyroxine were enrolled and allocated into two groups to receive oral vitamin D 20,000 IU weekly versus placebo for 24 weeks. Baseline biochemical values, body composition, handgrip strength, the five-times sit-to-stand test (5TSTS), HOMA-insulin resistance (IR), and QOL were measured before, after 3, and 6 months in both groups. Mixed model regression analysis was used to compare the outcomes between the two groups. The significant p-value was set at <0.05. Results There were 20 participants in each group. The time taken for 5TSTS in the vitamin D group was significantly lower than the placebo group at 3 (p = 0.032) and 6 months (p = 0.006). Other outcomes, including handgrip strength, body composition, HOMA-IR, and QOL, showed no significant difference between the two groups. Conclusion A supplement of vitamin D2 at 20,000 IU per week for 24 weeks could help improve performance in 5TSTS in I131-induced hypothyroidism patients.