HDCN Article Review/Hyperlink

Curhan GC, Willett WC, Speizer FE, Spiegelman D, Stampfer MJ

Comparison of dietary calcium with supplemental calcium and other nutrients as factors affecting the risk for kidney stones in women

Ann Int Med (Apr) 126:497-504 1997

Comment: The possibility that calcium supplementation is associated with an increased rate of stone disease is important, parti- cularly because there is much recent data that post-menopausal women with stones,like most demographic groups studied, have lower bone-density than their non-stone-forming peers. We need to know whether calcium supplementation in this group of patients is possible.

This study does not specify what calcium supplements the participants took, though the methods state that this information was solicited. One would guess that almost all of the subjects were taking calcium carbonate. There are however, a number of references, by Charles Pak, and one by John Rodman, suggesting that calcium citrate supplementation will not increase the lithogenicity of urine. This of course is due to the inhibitory effect of citrate on calcium stone formation. In addition, the preliminary evidence suggests that alendronate might be useful in the management of hypercalciuria, while increasing bone density. (see HDCN review of Weisinger's 1996 ASN abstract on this subject). The use of this drug would allow absorbed calcium to be deposited into bone, rather than into the urine. As Coe's accompany editorial implies, calcium supplementation without increasing calciuria would also be possible with co-administration of thiazides, which may have direct effects on bone themselves.

One strange finding in this paper is the absence of a stronger effect of calcium supplementation beyond the 1-100 mg per day level. In fact it is odd that there even is a significant number of women taking this small amount: most recommendations are for pre-menopausal women to take 500-1000 mg, and for post-menopausal women to take 1000-1500 mg per day. I don't think there is any really credible explanation for this finding, and it casts some doubt on the association. (David S. Goldfarb, M.D., NYU School of Medicine)

The full text of this paper is available from the ACP site.

See also the accompanying editorial by Coe et al.