Studies of the production and life span of erythrocytes in myeloid metaplasia.

By DAVID G. NATHAN AND NATHANIEL I. B11m.iN T HE PATHOGENESIS of myeloid metaplasia’ with or without myelofibrosis is obscure.24 Anemia may be a major cause of disability in this syndrome.2’3 The transfusion requirement may become so great due to premature destruction of red cells that splenectomy may be considered,5’#{176} despite the fact that the procedure was once thought to be contraindicated in this disease.7#{176} Since the spleen and liver may be the only apparent sites of red cell production in myeloid metaplasia, the indications for splenectomy are not well established. Measurement of the rates and sites of red cell production and destruction permits a better evaluation of the hematologic status of such patients. The purpose of this paper is to present the results of studies of four patients with agnogenic myeloid metaplasia and myelofibrosis and one patient with polycythemia vera with myeloid metaplasia. The studies included measurements of plasma and red cell iron turnover with Fe59, serial in vivo measurements of Fe59 in marrow, liver and spleen, the apparent red cell survival with Cr51, the rates of accumulation of Cr5’ in spleen and liver in vivo, and the red cell life span with glycine-2-C’4. The usual peripheral hematology, bone marrow examination and the measurement of fecal urobilinogen excretion were also performed.