Red cell enzymes were studied in 11 patients with refractory sideroblastic anemia. Eight of the cases were of the primary idiopathic type while three had an underlying (?) disease. The red cells were separated into several density groups by different flotation with phthalate ester mixtures. The glucose-6-phosphate dehydrogenase, 6-phosphogluconic dehydrogenase, hexokinase and pyruvate kinase activities and adenosine triphosphate contents were determined in each fraction, with special attention to the lightest and densest fractions.
It was found that the refractory anemia patients have a population of abnormal light red cells with a very high enzymatic activity, especially of hexokinase, a normal adenosine triphosphate content but relatively reduced surface charge. This abnormal population which so far seems typical to this disease, is probably another reflection of the disordered red cell proliferation and maturation seen in refractory anemia.