Iatrogenic hypercalcemia in hemodialysis patients.

Calcium carbonate is frequently used in large doses as a phosphorus binder in hemodialysis patients, which often results in hypercalcemia. In most studies in which calcium carbonate is prescribed to control serum phosphorus levels the patients are not given calcitriol. However, calcitriol may be necessary for suppression of parathyroid hormone. The risk of hypercalcemia when calcium supplements are used in conjunction with calcitriol has not previously been examined in detail. We reviewed the charts of 74 hemodialysis patients (119 patient dialysis years) to determine the relationship of serum calcium to calcitriol, calcium therapy, and PTH levels. Twenty-eight patients (38%) were hypercalcemic at some point. Calcitriol therapy significantly increased the risk of hypercalcemia, independently of calcium therapy (p = 0.032). However, patients on a low dose of calcitriol were more than twice as likely to be hypercalcemic than patients on higher doses. Mean PTH levels were lower in the patients on the lower doses of calcitriol, indicating less severe hyperparathyroid disease. We conclude that hypercalcemia is a common complication in hemodialysis patients on calcitriol and calcium carbonate. Whether lowering the dialysate calcium, as suggested by other investigators, will successfully decrease the risk of hypercalcemia without worsening hyperparathyroidism remains to be determined.