Renal aluminum excretion.

Urinary aluminum (Al) excretion was studied in humans with normal and impaired renal function. Al was measured by atomic absorption spectrometry. In healthy volunteers (n = 50), renal Al excretion was 12.2 +/- 8.5 micrograms/24 h. Two patients on plasma exchange therapy with normal renal function and an inadvertent load of 870 and 388 micrograms Al/treatment showed a 23 and 14% positive balance until next treatment. The renal pathway of excretion was shown to be important in 6 chronic renal failure patients on continuous peritoneal dialysis with residual renal function who eliminated in 24 h 51.4 +/- 24.0 micrograms Al by urine and only 27.2 +/- 18.4 micrograms Al across the peritoneum following a daily oral application of 342 mg Al. Studies with the isolated perfused rat kidney confirmed the limited renal capacity to eliminate Al. Al clearance declined from 0.75 to less than 0.08 mL/min when the kidney was perfused with 0.04-12.4 micrograms Al/mL medium. Al content of the kidney increased in a dose-dependent manner from less than 0.05 to 4.4 micrograms/kidney and reached saturation at 5 micrograms Al/mL medium.