Aluminum transfer during dialysis: a systematic review

Area of Science:

• Nephrology
• Toxicology
• Biochemistry

Background:

• Dialysis-dependent patients are vulnerable to aluminum toxicity due to impaired excretion.
• Aluminum contamination in dialysis fluid poses a significant risk.
• The mechanism of aluminum diffusion across dialysis membranes requires clarification.

Purpose of the Study:

• To test the hypothesis that aluminum transfer direction is determined by the concentration gradient between plasma and dialysate.
• To establish a predictive model for aluminum movement across dialysis membranes.

Main Methods:

• Systematic literature review of studies reporting plasma and dialysate aluminum concentrations and transfer direction.
• Inclusion of data from four patients from the authors' cohort.
• Analysis based on the ultrafiltrable fraction of plasma aluminum (17-23%) to define transfer scenarios.

Main Results:

• Out of 115 analyzed patients, 94% (108 patients) demonstrated aluminum transfer consistent with the hypothesis.
• Only three out of 111 patients showed results contrary to the predicted direction of aluminum transfer.
• The concentration gradient effectively predicts aluminum transfer direction in most cases.

Conclusions:

• Comparing ultrafiltrable plasma aluminum to dialysate aluminum accurately predicts transfer direction.
• Optimal dialysate aluminum concentration should be less than 20% of the maximum acceptable plasma level.
• To adhere to K/DOQI guidelines (plasma Al < 20 μg/L), dialysate Al should not exceed 4 μg/L; current K/DOQI recommendations (dialysate Al < 10 μg/L) may permit toxic plasma levels.