Pyridoxine-Responsive Anemia Conditioned by Isonicotinic Acid Hydrazide

Three patients are described who had a pyridoxine-responsive anemia while under treatment for pulmonary tuberculosis with INH and PAS. The red cells were hypochromic and target cells were common. Two cases also had microcytosis and one had ringed sideroblasts in the bone marrow. None became hematologically normal with therapy. A somnolent reaction occurred in two of the patients following the parenteral administration of large amounts of pyridoxine, and seemed related to it. The concentration of erythrocyte glutamic oxaloacetic transaminase was less than 25 per cent of the normal mean in two of the patients at the time of relapse.