Calcium balance in chronic kidney disease: walking the tightrope.

Calcium supplements for prevention and treatment of mineral and bone disorders in chronic kidney disease (CKD) have been alternately praised and damned. Clinical evidence in favor of either attitude has been lacking. The calcium balance study by Spiegel and Brady in patients with late stage 3 and stage 4 CKD suggests that CKD subjects ingesting 2000 mg of elemental calcium per day are in marked positive balance. Methodological limitations such as unproven steady state warrant caution and confirmatory studies.