The Effect of Intravenous Iron on Oxidative Stress in Hemodialysis Patients at Various Levels of Vitamin C

Abstract

Background/Aims: Vitamin C levels decrease during hemodialysis (HD), which deteriorates antioxidant defense. Vitamin C may also act pro-oxidatively, via reduction in Fe(III). We sought to determine whether intravenous iron (Fe_iv)-induced oxidative stress differs in HD patients with low and physiological vitamin C levels and whether intravenous vitamin C (C_iv) administration during HD would change the response to Fe_iv. Patients and Methods: Twenty patients with vitamin C deficiency (median 15.7 µmol/l, range 8.0–22.7) received Fe_iv (100 mg iron sucrose between 150 and 180 min of HD). After 4 weeks of oral supplementation, the levels of vitamin C were comparable with those of controls (60.1 µmol/l, range 47.4–70.9). Patients were subsequently treated with (1) Fe_iv, (2) Fe_iv and continuous 2 mg/min C_iv throughout HD, (3) saline (S), and (4) S+C_iv. Plasma thiobarbituric acid reacting substances (TBARS) and vitamin C were assessed before, during and after FE_iv(S), and 15, 30 and 60 min after infusion. Results: Fe_iv induced a comparable rise in TBARS in patients with vitamin C deficiency (before Fe_iv, 1.9 µmol/l, range 1.4–1.9; after Fe_iv, 2.6 µmol/l, range 2.3–2.9; p < 0.01) and in those with normal vitamin C (before Fe_iv, 1.9 µmol/l, range 1.7–2.1; after Fe_iv, 2.6 µmol/l, range 2.5–2.9; p < 0.01). Fe_iv+C_iv resulted in a greater increase in TBARS (after Fe_iv, 3.1 µmol/l, range 2.8–3.2) compared with Fe_iv (p < 0.01). Conclusion: Iron sucrose-induced oxidative stress is comparable in HD patients with vitamin C deficiency and in those with normal vitamin C. We documented a pro-oxidative effect of vitamin C during Fe_iv+C_iv administration.