Calcium plus Vitamin D and the Risk of Fractures

To the Editor: The increased incidence of nephrolithiasis among patients taking supplemental calcium carbonate that was reported by Jackson et al. (Feb. 16 issue) 1 might have been avoided if calcium citrate had been given. It has been shown that urinary calcium oxalate crystals that form in the presence of hypercalciuria and hyperoxaluria develop into clinically important stones only after aggregation into larger particles. This aggregation is inhibited by citrate at physiologic concentrations. 2 , 3 The data in Table 3 in the report suggest that calcium and vitamin D reduced the incidence of hip fracture more in older patients than in younger . . .