Effect of vitamin D supplementation on 24-hour urine calcium in patients with calcium Urolithiasis and vitamin D deficiency.

PURPOSE

Hypercalciuria is one of the risk factors for calcium kidney stone formation (the most common type of urinary stones). Although vitamin D deficiency is prevalent among urolithiasis patients, the effect of vitamin D supplementation on urine calcium in these patients is still unclear.

MATERIALS AND METHODS

In this retrospective study, medical and laboratory tests records of 26 patients with recurrent calcium kidney stones and vitamin D deficiency treated with 50000IU vitamin D per week for 8-12 weeks were analyzed. The changes in 24-hour urine calcium (24-h Ca), serum 25-hydroxyvitamin D (25 (OH) D), serum parathormone (PTH), other 24-hour urine metabolites and calculated relative supersaturations of calcium oxalate (CaOxSS), calcium phosphate (CaPSS) and uric acid (UASS) were assessed. Moreover, correlations between changes in 24-h Ca and other aforementioned variables were assessed.

RESULTS

Serum 25 (OH) D and 24-h Ca increased after vitamin D supplementation, while serum PTH decreased (p < 0.001, for all analyses). The levels of 24-hour urine sodium and urea increased significantly (p = 0.005 and p = 0.031, respectively). The levels of CaOxSS and CaPSS increased, but the changes were not significant (p = 0.177, and p = 0.218, respectively). There were no correlations between the changes in 24-h Ca and serum 25 (OH) D or PTH.

CONCLUSIONS

The result of current study suggests that although urine Ca increased in vitamin D supplemented patients, this increase was not associated with the increase in serum vitamin D and may be due to other factors such as dietary factors. Further randomized clinical trials considering other factors associated with urine Ca are warranted.