MCV as a guide to phlebotomy therapy for hemochromatosis

BACKGROUND: A multitude of recommendations exist for laboratory assays to m onitor the pace and endpoints of phlebotomy therapy for hemochromatosis. Al l of these recommendations rely on an assessment of storage iron to guide t reatment, and none have been prospectively evaluated. STUDY DESIGN AND METHODS: Nine consecutive patients underwent serial monito ring of Hb, MCV, transferrin saturation, and ferritin during weekly phlebot omy to deplete iron stores (induction therapy) and less frequent sessions t o prevent iron reaccumulation (maintenance therapy). Changes in MCV and Hb were used to guide the pace of phlebotomy over a median of 7 years of follo w-up. RESULTS: During induction therapy, the MCV increased transiently because of reticulocytosis and then stabilized for a prolonged period before decreasi ng more sharply which reflected iron-limited erythropoiesis. Iron depletion was achieved after a median of 38 phlebotomies and removal of 9.0 g of iro n. Maintenance phlebotomy was targeted to maintain the MCV at 5 to 10 perce nt below prephlebotomy values and the Hb at > 13 g per dL. Transferrin satu ration fluctuated considerably during treatment, but remained below 35 perc ent during MCV-guided maintenance therapy. Ferritin values were not useful guides to the pace of phlebotomy. The median maintenance therapy phlebotomy interval was 7.5 weeks (range, 6-16), which corresponded to an average dai ly iron removal of 35 to 67 mug per kg. Most patients showed evidence of ir on reaccumulation at phlebotomy intervals of 8 weeks or more. CONCLUSION: The MCV is an inexpensive, precise, physiologic indicator of er ythropoietic iron availability. When used in conjunction with the Hb, it is a clinically useful guide to the pace of phlebotomy therapy for hemochroma tosis.