Evaluation of reticulocyte hemoglobin content, percentage of hypochromic red blood cells, and ratio of serum transferrin receptor level/serum iron level as markers of iron-deficiency erythropoiesis in patients undergoing hemodialysis

Reticulocyte hemoglobin content (CHr), percentage of hypochromic red blood cells (%HRC, level of serum transferrin receptor(sTfR), and sTfR/serum iron ratio (sTfR/Fe) were measured in 132 hemodialysis patients. On univariate analysis, CHr was positively correlated with serum amyloid A (SAA) and negatively correlated with Kt/V. %HRC showed a positive correlation with the recombinant human erythropoietin (rHuEPO) dosage. The dependency of each iron-status index on 5 variables, SAA, sFt, TS, KtN, and dose of rHuEPO administered, was determined by stepwise multiple regression analysis. CHr was influenced only by TS, while %HRC, sTfR and sTfR/Fe were influenced by both logrHuEPO dosage and TS. Patients whose hemoglobin concentration increased by more than 1 g/dl following iron supplementation were defined as Iron-Responders, and the remaining patients were defined as Iron-Nonresponders. Fifteen out of 20 patients responded to 10 consecutive intravenous administrations of 80 mg of saccharated ferric oxide at each dialysis session, while five did not. The baseline CHr was significantly lower in Iron-Responders than Iron-Nonresponders. The baseline %HRC, sTfR, and sTfR/Fe were significantly higher in Iron-Responders than Iron-Nonresponders. The baseline CHr, %HRC, and sTfR/Fe were correlated with the degree of change in Hb concentration at 4 weeks of iron supplementation. The absolute change in CHr at 2 weeks of iron supplementation was positively correlated with the absolute change in Hb concentration over the first 4 weeks. Conclusion: (1) In assessing the iron metabolic status of dialysis patients, CHr, %HRC, and sTfR/ Fe were unique indices compared with the ordinary indices, particularly in diagnosing the functional iron deficiency state. (2) CHr was a valuable marker of iron deficiency anemia and could predict the degree of increase in Hb level following iron supplementation. (3) The %HRC and sTfR/Fe seemed to reflect both erythropoiesis induced by rHuEPO and the iron supply to erythropoietic cells.