A randomized trial comparing 2.5 mEq/L calcium dialysate and calcitriol to 3.5 mEq/L calcium dialysate in patients on peritoneal dialysis.

Peritoneal dialysate containing 2.5 mEq/L of calcium has been used to prevent hypercalcemia when calcium-containing phosphate binders are given. However, worsening of hyperparathyroidism may result. Calcitriol used in conjunction with 2.5 mEq/L calcium dialysate is an attractive alternative, but has not been examined in a controlled trial. Eighteen patients were randomly assigned to either a control group (3.5 mEq/L calcium dialysate without calcitriol) or a study group (conversion to 2.5 mEq/L calcium dialysate with oral calcitriol, median dose 0.25 microgram/day). The initial mean serum calcium (9.9 vs 9.6 mg/dL), phosphate (5.4 vs 5.6 mg/dL), median n-terminal parathyroid hormone (PTH) levels (71 vs 55 pg/mL, normal < 25), and median 1,25 (OH)2 vitamin D levels (4 vs 5 pg/mL, normal 15-60 pg/mL) were not different in the two groups. After 8 weeks the serum calcium and phosphate were unchanged from baseline in both groups. The 9 patients who converted to 2.5 mEq/L calcium dialysate had an insignificant fall in the PTH level, not different from the control group. The median 1,25 (OH)2 vitamin D level rose from 4 to 23 pg/mL (p = 0.003) on calcitriol, but remained unchanged in the control group (5 pg/mL). The median doses of oral calcium (0.9 vs 1.1 g/day) and the frequency of serum calcium levels greater than 11 mg/dL (4/9 vs 3/9 patients, 10% vs 8% of all values) were similar in the study and control groups. Aluminum hydroxide was required intermittently for serum phosphate control in 3 patients on 2.5 mEq/L calcium dialysate and 4 on 3.5 mEq/L calcium dialysate.(ABSTRACT TRUNCATED AT 250 WORDS)