Calcium loading, calcium accumulation, and associated cardiovascular risks in dialysis patients.

Calcium and phosphate imbalances are important mutable risk factors for cardiovascular disease in chronic kidney disease (CKD). Nearly all dialysis patients require phosphate binders. These include traditional calcium-based compounds and, more recently, the calcium-free, metal-free, non-absorbed agent, sevelamer hydrochloride. Both binder types reduce serum phosphorus, but differ with respect to calcium load and metabolism. Absorption from calcium-based agents very likely promotes positive total calcium balance in many patients. Positive calcium balance is inappropriate in adults and may promote or accelerate soft-tissue and vascular calcification even in the absence of hypercalcemia. Calcium accumulation in heart and vascular tissues contributes to rapidly progressive cardiovascular calcification - a strong predictor of cardiovascular and all-cause mortality in stage 5 CKD. More than two-thirds of stage 5 CKD patients have calcification scores above the 75th percentile for matched controls -- scores associated with extremely high risk of cardiovascular events and death.