Despite concern about an increased risk for kidney stones with vitamin D supplementation, researchers have concluded that a serum 25-hydroxyvitamin D (25[OH]D) level of 20 to 100 ng/mL has no significant association with kidney stone incidence.
Among 2,012 individuals followed prospectively for a median of 19 months, 13 reported having developed a kidney stone during the study period. Although body mass index (BMI) was significantly associated with kidney stone risk (patients with a BMI of 30 or greater had a higher incidence rate of kidney stones than did others), the association between serum 25(OH)D and kidney stone development was not statistically significant.
Cedric F. Garland, DrPH, of the University of California San Diego (UCSD) School of Medicine, and colleagues reported online in the American Journal of Public Health that the mean 25(OH)D serum level among the 13 patients who had kidney stones was 47 ng/mL, with a median serum level of 43 ng/mL. By comparison, the mean and median 25(OH)D serum levels among those without kidney stones were both 50 ng/mL. Eight patients with kidney stones were below the median 25(OH)D serum level of 50 ng/mL, with the levels in the five remaining participants equal to or above the median.
“Mounting evidence indicates that a vitamin D serum level in the therapeutic range of 40 to 50 ng/mL is needed for substantial reduction in risk of many diseases, including breast and colorectal cancer,” Dr. Garland explained in a UCSD statement, adding that this serum level is generally only achieved with vitamin D supplementation. “Our results may lessen concerns by individuals about taking vitamin D supplements, as no link was shown between such supplementation and an increased risk for kidney stones.”
Males and individuals aged 55 years and older had a higher incidence rate of kidney stones compared with other participants.