Assessing iron status in children with chronic renal failure on erythropoietin: which measurements should we use?

Iron deficiency severely limits the efficacy of recombinant human erythropoietin (EPO). In order to determine how best to identify and monitor children at risk of developing iron deficiency, we serially measured several parameters of iron status in nine children before and during a 24-week period of EPO therapy. Serum ferritin was the best predictor of development of iron deficiency, five of the nine children developed iron deficiency, characterised by a poor haemoglobin response or evidence of microcytosis and hypochromia; all had a serum ferritin of 60 micrograms/l or less at the start of EPO. Haemoglobin response was also related to change in mean red cell volume (MCV); a falling MCV, irrespective of absolute value, accompanying a poor response to EPO. Iron treatment in five children resulted in significant improvements in haemoglobin and iron status parameters. Although MCV remained low, there was a marked increase in red cell volume distribution width after iron, which may be of value in monitoring the response to iron therapy. We suggest that children with a serum ferritin of 60 micrograms/l or less and those who develop a falling MCV during EPO treatment should receive high-dose oral iron supplementation before and during treatment with EPO.