Elimination of absorbed aluminum in patients undergoing continuous ambulatory peritoneal dialysis

Intestinal absorption of aluminum (Al) from the phosphate binder aluminum-hydroxide-chloride (PhosphonormR) and successive renal and peritoneal Al elimination were studied in 11 patients undergoing continuous ambulatory peritoneal dialysis (CAPD). Al was measured by atomic absorption spectrometry in serum, urine, and dialysis fluid. Al levels in serum of all patients increased in average from 28.6 micrograms/l immediately before to a peak level of 41.6 microgramsWl 4 h after intake of 342 mg Al. After 24 h serum Al (34.0 micrograms/l) was still increased. Elimination across the peritoneum increased from 5.6 micrograms Al during the first 4 h to peak levels of 12.9 micrograms between hour 8 and 12 and decreased to 8.1 micrograms during the last 12 h. The Al clearance of the peritoneum was 0.43 ml/min. In the 6 patients with residual diuresis the renal Al excretion was higher than the peritoneal removal (48.1 micrograms/24 h vs. 24.8 micrograms/24 h). The renal Al clearance amounted to 1.6 ml/min. Assuming a gastrointestinal absorption quotient of 0.1% it is concluded that Al removal by CAPD in patients receiving 342 mg Al/day is not sufficient to prevent Al accumulation. In patients with remaining diuresis, the renal Al elimination exceeds the Al removal by the peritoneum.