Association between serum 25-hydroxyvitamin D and nephrolithiasis: the National Health and Nutrition Examination Survey III, 1988-94.

BACKGROUND The role of vitamin D in kidney stone disease is controversial. Current evidence is inconsistent and existing studies are limited by small sample populations. METHODS We used the third National Health and Nutrition Examination Survey (NHANES III), a large US population-based cross-sectional study, to determine the independent association between serum 25-hydroxyvitamin D [25(OH)D] concentration and prevalent kidney stone disease in a sample of 16 286 men and women aged 18 years or older. A prevalent kidney stone was defined as self-report of any previous episode of kidney stones. RESULTS Among 16 286 adult participants, 759 subjects reported a history of previous kidney stones. Concentrations of serum 25(OH)D were not different between stone formers and non-stone formers (mean 29.28 versus 29.55 ng/mL, P = 0.57). Higher 25(OH)D concentration was not associated with increased odds ratio (OR) for previous kidney stones [OR = 0.99; 95% confidence interval (CI) 0.99-1.01] after adjustment for age, sex, race, history of hypertension, diabetes, body mass index, diuretic use and serum calcium. Furthermore, after we divided 25(OH)D concentrations into quartiles, or into groups using clinically significant cut-offs (e.g. 40 and 50 ng/mL), still no significant differences were found in stone formation in group comparisons. CONCLUSIONS High serum 25(OH)D concentrations are not associated with prevalent kidney stone disease in NHANES III participants. Prospective studies are needed to clarify the relationship between vitamin D and kidney stone formation, and whether nutritional vitamin D supplementation will increase risk of stone recurrence.