Aluminum transfer during hemodialysis

Abstract

Aluminum concentrations were measured in plasma and urine of normal subjects and chronic hemodialysis patients by using flameless atomic absorption spectrophotometry. Plasma aluminum averaged 7 μg/liter in 13 normal subjects, who excreted an average of 13 μg/day. Predialysis plasma concentrations in 16 patients on low aluminum dialysate (study A) averaged 58 μg/liter, with a postdialysis mean of 63 μg/liter (P<0.02). Urinary aluminum excretion averaged 9 μg/day during the longest interdialysis interval. Nineteen patients using high aluminum dialysate (study B-1) had mean plasma concentrations of 168 predialysis and 265 μg/liter postdialysis (P < 0.001), and they excreted 48 μg/day of aluminum (P< 0.01 vs study A). After two months of dialysis with low aluminum dialysate (study B-2), 14 patients were restudied. Predialysis aluminum concentration averaged 93, and postdialysis, 114 μg/liter (P < 0.05). Both pre- and postdialysis plasma levels differed significantly among the three groups. During study B-2, aluminum excretion averaged 19 μg/day, significantly less than study B-1 (P< 0.01). One patient was dialyzed for 60 min with dialysate containing 128 μg/liter aluminum, and for the subsequent 140 min, with 3 μg/liter aluminum dialysate. Plasma aluminum before dialysis was 43 μg/liter. Values across the dialyzer at 15 min were 76 and 195 μg/liter; at 60 min, 148 and 205 μg/liter; and at 200 min, 110 and 114 μg/liter. We conclude that significant amounts of aluminum can be transferred to plasma during dialysis if dialysate contains virtually any aluminum since aluminum is bound to a nondialyzable plasma constituent. The binding also precludes the removal of aluminum from the patient during dialysis.