IT is often difficult to distinguish between Addisonian pernicious anemia and other macrocytic anemias that will not respond to the specific materials potent in pernicious anemia. The purpose of this paper is to demonstrate some of the findings in a study of the distribution of red Blood cell diameters that seem to be of help in making such a differentiation. Demonstrable differences of cell diameters in various kinds of macrocytic anemia will suggest fundamental differences of etiology and hence of treatment in such cases.

Mogensen 1 has commented upon differences in the distribution of red Blood cell diameters in macrocytic anemias, comparing pernicious anemia with anemias refractory to liver therapy. Such macrocytic anemias have been discussed as cases of refractory anemia by Rhoads and Barker 2 and Bomford and Rhoads. 3 A certain type of refractory macrocytic anemia has been designated “achrestic” anemia by Israels and Wilkinson. 4 Rhoads and Barker divided refractory anemia into primary and secondary groups. In the primary group, the anemia seemed to exist independently of any other pathologic process. In the secondary group, the anemia depended upon a recognizable cause, such as Hodgkin's disease, degenerative disease of the liver, tuberculosis of the bone marrow, or the like. Bomford and Rhoads classified the bone marrows of refractory anemias into four major groups according to distinctive histologic characteristics. It is often difficult clinically to separate these cases of refractory macrocytic anemia from those of pernicious anemia until a proper trial with a liver preparation has been made. Pathologic processes upon which the manifestations of the secondary group depend may remain hidden during life. The clinical features may resemble closely those of pernicious anemia, including glossitis and achlorhydria. The histologic character of the bone marrow is often inconsistent with the Blood findings, being aplastic, hypoplastic, hyperplastic, or sclerotic.