Background: Intravenous iron is typically administered during the hemodialysis (HD) procedure. HD patients may be prescribed high-flux (HF) or high-efficiency (HE) dialysis membranes. The extent of iron sucrose and iron dextran removal by HD using HF or HE membranes and by ultrafiltration rate (UFR) is unknown.
Methods: Two in vitro HD systems were designed and constructed to determine the dialyzabiltiy of iron from a simulated blood system (SBS) containing 100 mg iron sucrose or iron dextran (system A) or 1000 mg iron sucrose (system B). Both in vitro systems utilized a 6-L closed-loop SBS system that was subject to 4 different HD conditions conducted over 4 hours: HE membrane + 0 ml/hr UFR; HE membrane + 500 ml/hr UFR; HF membrane + 0 ml/hr UFR; HF membrane + 500 ml/hr UFR. Blood flow and dialysate flow rates were 500 ml/min and 800 ml/min, respectively. The dialysate compartment was a 192-L open system for system A and a 6-L closed-loop system for system B. Samples from the SBS and dialysate compartments were taken at various time points and iron elimination rate and HD clearance was determined. Iron removal from the SBS > 15% was considered clinically significant.
Results: The greatest percentage removal from the SBS was 13.5% and -0.03% utilizing system A and B, respectively. Iron sucrose and iron dextran dialysate concentration was below the lower limits of assay (< 2 ppm) for system A. Dialysate recovery of iron was negligible: 0-5.4 mg system A and 5.47-23.59 mg for system B. Dialyzer type or UFR did not affect iron removal.
Conclusion: HF or HE dialysis membranes do not remove clinically significant amounts of iron sucrose or dextran formulations over a 4-hour HD session. This effect remained constant even controlling for UFR up to 500 ml/hour. Therefore, iron sucrose and iron dextran are not dialyzed by HE or HF dialysis membranes irrespective of UFR.