Iron induced increase in red cell size in haemodialysis patients

In a group of haemodialysis patients who were iron loaded secondary to parenteral iron administration a slight but significant increase in red cell size was noted when compared to a normal population. This macrocytosis was not related to serum B12 or folate levels, or to the reticulocyte count. On stopping iron therapy both mean corpuscular volume (MCV) and mean corpuscular haemoglobin (MCH) values declined significantly as did serum ferritin and iron levels. Bone marrow smears were of normal or increased cellularity. When iron therapy was discontinued there was a steady fall in serum ferritin levels without a drop in haemoglobin values suggesting that the excess iron was available for haemopoiesis. These findings suggest that the increase in red cell size in this group of patients may have been induced directly by iron overload.