Bone mineral density and fracture among prevalent kidney stone cases in the Third National Health and Nutrition Examination Survey

Concern that people who form kidney stones may have reduced bone mineral de nsity (BMD) and increased fracture risk has motivated clinical and populati on-based studies, but findings are inconsistent. In this cross-sectional st udy, we use the Third National Health and Nutrition Examination Survey (NHA NES III) to determine whether a history of kidney stones (n = 793) is assoc iated with lower femoral neck BMD and whether the association is similar fo r men and women. We further ask whether dietary calcium modifies the associ ation between kidney stone history and BMD and whether there is an associat ion between kidney stone history and prevalent spine or wrist fracture. We find that men with kidney stone history have lower femoral neck BMD than me n without kidney stone history after adjusting for age, body mass index (BM I), race/ethnicity, and other potential confounders. The effect of kidney s tone history on BMD is weaker for women. Men with kidney stone history also are more likely to report prevalent wrist and spine fractures. Dietary cal cium, represented by usual milk consumption, is associated positively with BMD for both men and women and modifies the effect of kidney stone history on BMD for men. For men who form kidney stones, milk consumption is associa ted more strongly with femoral neck BMD than for men without such a history . The effect modification is such that the difference in BMD between men wi th and without kidney stone history is observed only at lower levels of mil k consumption.