Calcium Replacement in ESRD Patients

Introduction to Calcium Management

The American Journal of Kidney Diseases recommends calcium replacement in ESRD patients should be approached with caution, using a dialysate calcium concentration of 1.50 mmol/L or higher to maintain neutral or positive calcium balance while avoiding hypercalcemia and PTH oversuppression 1, 2

Calcium balance in ESRD patients is determined by multiple factors including dietary intake, calcium-based phosphate binder use, vitamin D status, dialysate calcium concentration, and ultrafiltration volumes 2
Patients on intensive hemodialysis who discontinue calcium-based phosphate binders are at risk for negative calcium balance when using low calcium dialysate (1.25 mmol/L) 3, 1
Negative calcium balance can lead to secondary hyperparathyroidism and decreased bone mineral density (BMD) 4

A dialysate calcium concentration of 1.5 mmol/L has been shown in mass-balance studies to maintain neutral calcium balance 1
Higher dialysate calcium concentrations (1.5-1.75 mmol/L) have been shown to reverse increases in alkaline phosphatase and PTH levels in patients on intensive hemodialysis 3
Increasing dialysate calcium concentration from 1.25 to 1.75 mmol/L has been shown to prevent decreases in bone mineral density 4, 5

Regular monitoring of serum calcium, phosphate, PTH, and alkaline phosphatase levels is essential 3
Rising bone alkaline phosphatase and PTH levels suggest that higher dialysate calcium may be required 3, 1

Prevents secondary hyperparathyroidism 3
Maintains bone mineral density 4
Reduces risk of fragility fractures 1
Improves management of bone mineral metabolism 4
Theoretical risk of positive calcium balance promoting vascular calcification 4, 5

Current literature does not support worsening of vascular or ectopic calcification with appropriate calcium replacement 4, 5
The risk of vascular calcification may be higher in patients who have low weekly ultrafiltration volumes 4

Using low calcium dialysate (1.25 mmol/L) in patients who have discontinued calcium-based phosphate binders can lead to negative calcium balance 1, 4
Failure to consider all sources of calcium intake (dietary, binders, dialysate) can lead to calcium imbalance 2
Ignoring rising alkaline phosphatase and PTH levels, which may indicate need for higher dialysate calcium 3, 1

The Canadian Society of Nephrology guidelines suggest using dialysate calcium of 1.50 mmol/L or higher while carefully monitoring biochemical parameters to avoid both negative calcium balance and hypercalcemia 1, 2