Effect of two vitamin D repletion protocols on 24-h urine calcium in patients with recurrent calcium kidney stones and vitamin D deficiency: a randomized clinical trial.

OBJECTIVES: To evaluate the effects of two vitamin D repletion therapies (cholecalciferol) on serum levels of 25-hydroxyvitamin D (25(OH)D) and 24-h urine calcium in patients with recurrent calcium kidney stones and vitamin D deficiency (VDD). DESIGN, SETTING, PARTICIPANTS: A parallel-group randomized controlled clinical trial on patients who referred to Labbafinejad kidney stone prevention clinic, Tehran, Iran. From 88 recurrent calcium stone formers, 62 patients completed the study. The age of participants was 18-70 years who had serum 25(OH)D levels of 10-20 ng/ml. INTERVENTION: Participants received oral cholecalciferol 2000 IU daily for 12 weeks or 50,000 IU weekly for 8 weeks. MAIN OUTCOME MEASURES: Study variables including 24-h urine calcium, supersaturations of calcium oxalate and calcium phosphate, serum 25(OH)D and parathyroid hormone were measured at the beginning of the study and after 12 weeks. RESULTS: The 24-h urine calcium significantly increased in both groups (ß = 69.70, p < 0.001), with no significant difference between treatments. Both groups showed no significant change in the supersaturation levels of calcium oxalate and calcium phosphate. Serum levels of 25(OH)D increased significantly (ß = 12.53, p < 0.001), with more increase in the 50,000 IU group (ß = 3.46, p = 0.003). Serum parathyroid hormone decreased in both groups (p < 0.001). CONCLUSIONS: Although both treatment protocols increased 24-h urine calcium, they did not increase the supersaturation state of calcium oxalate or calcium phosphate. Trial registration IRCT20160206026406N4, 13/08/2019.