Nontransferrin‐bound iron in the plasma of haemodialysis patients after intravenous iron saccharate infusion

BACKGROUND: Many haemodialysis patients treated with recombinant human erythropoietin (r-HuEPO) receive intravenous iron supplementation on a regular basis. It has been shown previously that this may result in a transient "oversaturation" of transferrin. METHODS: Ten stable haemodialysis patients on r-HuEPO treatment received 100 mg iron saccharate in 60 min, and 1 week later 100 mg in 6 min. Conventional iron metabolism parameters and nontransferrin-bond iron, detected with HPLC after addition of nitrilotriacetate and pretreatment with cobalt, were measured. Also, iron was measured in dialysate. RESULTS: Serum iron increased from 9.6 +/- 6.2 to 213.7 +/- 49.4 micromol L(-1) (P < 0.001) when iron was given in 60 min, and from 11.1 +/- 4.7 to 219.3 +/- 43.7 micromol L(-1) (P < 0.001) when iron was given in 6 min. Transferrin saturation increased from 0.22 +/- 0.18 to 4.75 +/- 1.35 in protocol 1 and 0.26 +/- 0.16 to 4.91 +/- 1.38 in protocol 2. Nontransferrin-bound iron increased from 0.74 +/- 0.69 to 3.79 +/- 1.41 micromol L(-1) in protocol 1, and from 0.90 +/- 0.92 to 2.90 +/- 0.96 micromol L(-1) in protocol 2. No significant iron concentrations were found in dialysate before or during the iron saccharate infusion. CONCLUSION: Nontransferrin-bound iron exists in plasma of dialysis patients after infusion of iron saccharate. There was no difference when 100 mg iron was given in 60 min or in 6 min. Before iron infusion, appreciable concentrations of nontransferrin-bound iron could already be detected. The clinical significance is not clear, but the findings may be important since nontransferrin-bound iron can act as a catalytic agent in the formation of hydroxyl radicals, thus potentially inducing cell damage and atherosclerosis.