Calcium supplementation: lessons from the general population for chronic kidney disease and back

Abstract

Purpose of review: Concern that calcium use may increase cardiovascular risk was previously the domain of nephrologists. By contrast, calcium supplementation has been promoted within the general community as beneficial to the maintenance of bone mineral density, as an adjunct to osteoporosis therapies and as potentially useful for cardiovascular health.

Recent findings: Studies of patients with normal serum creatinine levels have reported that combined calcium and vitamin D supplementation reduced fracture risk, and osteoporosis trials have generally included calcium and vitamin D in placebo and active arms. However, an increased risk of myocardial infarction and other cardiovascular events has now been reported in secondary analysis of a fracture study of patients taking calcium or placebo, in subsequent meta-analysis of 15 similar studies, and most recently in re-analysis of the Women's Health Initiative calcium, vitamin D dataset. These reports have been criticized regarding event ascertainment, adjudication and the use of composite outcomes.

Summary: Patients with chronic kidney disease (CKD) have impaired renal calcium regulation, abnormal bone turnover and are predisposed to positive calcium balance. If these general population data are proven, they should heighten our unease regarding the use of calcium salts in all stages of CKD, and particularly for patients with prevalent vascular calcification, suspected adynamic bone and high bone turnover.