Assessment of iron deficiency in chronic hemodialysis patients: investigation of cutoff values for reticulocyte hemoglobin content

Background. Recently, the usefulness of reticulocyte hemoglobin content (CHr) as a ferrokinetic marker in hemodialysis patients who receive recombinant human erythropoietin (rHuEPO) has been reported. However, a definite index for iron deficiency has not been established. In this study, a CHr cutoff value was investigated. Methods. We retrospectively selected 27 hemodialysis patients by the following criteria: (1) hematocrit (Ht) values less than 30%, (2) patients receiving a stable dose of rHuEPO for at least 3 months, (3) patients who had not received iron supplements for at least 3 months, and had begun receiving iron supplements, (4) the doses of rHuEPO and iron supplements were unchanged for 8 weeks following the start of iron administration. The iron supplement was administered at a dose of 40 mg/week, and Ht, CHr, transferrin saturation (TSAT), and serum ferritin were measured. The difference between the peak Ht value obtained at weeks 4–8 and Ht at baseline was calculated (ΔHt). Patients with a ΔHt of 3% or more were categorized as iron-deficient at baseline (group 1; n = 17). Patients with a ΔHt of less than 3% were categorized as iron-sufficient at baseline (group 2; n = 10). Each parameter was compared between the groups. Results. Significant negative correlations between ΔHt and CHr at baseline, and ΔHt and TSAT at baseline were observed. CHr and TSAT were significantly lower in group 1 than in group 2 at baseline. CHr was less than 32 pg in all patients in group 1, and greater than 32 pg in nine of the ten patients in group 2. If the CHr cutoff value was 32 pg, sensitivity was 100% and specificity was 90%. Conclusions. It is considered that 32 pg is appropriate for the CHr cutoff value. Received: June 5, 2002 / Accepted: November 18, 2002 Correspondence to:K. Mitsuiki