EFFECT OF SPLENECTOMY ON THE HÆMODILUTIONAL ANÆMIA OF SPLENOMEGALY

Red-blood-cell (R.B.C.) mass and plasma volume were measured in ten patients with splenomegaly and low or low-normal hæmoglobin levels. In nine patients the plasma volume was considerably raised, the increase being related to the size of the spleen. The R.B.C. mass was normal or increased, but 13-26% of this increase was present as a " pool " within the spleen. After splenectomy in eight patients and medical treatment in two the blood-volume fell immediately, and by an amount which corresponded closely to the R.B.C. and plasma content of the removed spleen. Subsequently, over 18 months there was a slower reduction in plasma volume which was probably due to a gradual return of erythropoietic activity to normal. These changes resulted in a two-phase increase in hæmoglobin concentration. The one exception was a patient with thalassæmia major in whom the plasma volume after an initial decrease gradually returned to the preoperative level.