RED-CELL FERRITIN, A MARKER OF IRON-DEFICIENCY IN HEMODIALYSIS-PATIENTS

Estimation of red cell ferritin (RCFer) may give a good indication of iron supply to the erythron and it may therefore be clinically useful for the detection of functional iron deficiency. In a cross-sectional study of hemodialysis patients on erythropoietin (EPO) therapy and reg ular oral iron we have compared the RCFer levels with conventional ind icators of iron status. The patients studied, 19 female, 48 male, mean age 62 +/- 3.6 years (range 20-83 years) were characterized by the fo llowing mean parameters: aluminum 1.24 +/- 0.12 mu mol/L, PTH 115.7 +/ - 39 pg/mL, vitamin B-12 626 +/- 71.2 ng/L, serum folate 18.8 +/- 2.2 mu g/L, and hemoglobin 9.8 +/- 0.3 g/dL (range 7.3-12.4). The median s erum ferritin (SF), RCFer total iron binding capacity (TIBC), transfer rin saturation (TS), and serum iron were 68 mu g/L, 14.1 ag ferritin/r ed cell, 57 mu mol/L, 20% and 11.5 mu mol/L, respectively. Eleven pati ents had a reduced RCFer (<7 ag ferritin/red cell), 5 had a SF of <15 mu g/L and 22 a TS of <16%. The occurrence of functional iron deficien cy was suggested by the presence pf 10 subjects with reduced RCFer des pite normal SF levels (15-240 mu g/L). Four patients with reduced SF s howed acceptable levels of RCFer, suggesting that some patients may ma intain an adequate iron supply despite diminished iron scores. Despite oral iran therapy a significant number of patients (63%) on regular h emodialysis remain relatively iron deficient with a serum ferritin of less than 100 mu g/L. It has previously been proposed that oral iron p rovides adequate supplementation during increased demand caused by EPO stimulation. The present study has demonstrated overt iron deficiency in five subjects and suggests functional iron deficiency in a further seven (22% of total patients). We therefore conclude that oral iron t herapy cannot maximize the response to EPO.