Intravenous iron dextran is frequently prescribed for iron-deficient hemodialysis patients, a practice that has increased during the erythropoietin era. Whether iron dextran is removed by hemodialysis has been a concern, especially for high permeability membranes. The purpose of this in vitro study was to measure iron dextran clearance by nine different hemodialyzers (Fresenius F3, F8, and F80B; Baxter CF25, CA150, CA210, and CT190; Toray BK2.1P; and Hospal Filtral 16) representing six types of membranes (polysulfone, cuprophane, cellulose acetate, cellulose triacetate, polymethylmethacrylate, and polyacrylonitrile) and including membranes considered high efficiency and high flux, Clearances were assessed using a closed-loop, fixed-volume reservoir model. Absolute drug removal also was determined over the 30-minute experiments, Iron dextran clearance did not exceed 25 mL/min, and clearances also were minimal after a single automated reuse with glutaraldehyde sterilant. A maximum of 8% of iron dextran was removed during the experiment, We conclude that iron dextran clearance by the nine hemodialyzers studied was small or too low to be detected in this sensitive in vitro dialysis system and that adjusting dosing schedules is not needed. (C) 1995 by the National Kidney Foundation, Inc.