In cryptogenetic splenomegaly, although there is consistently a significant reduction in hemoglobin concentration and in the red cell count, the total red cell volume may be reduced, normal or increased.
Following splenectomy the total red cell volume is either within normal limits or is increased, yet significant anemia persists.
Before splenectomy a significant increase in plasma volume is consistently present. Following splenectomy the plasma volume falls, but it remains significantly greater than normal. It would appear that the greater the plasma volume before splenectomy the greater is the fall following splenectomy. This fall in plasma volume is not a prompt response to splenectomy, for the fall which occurs one month after splenectomy is equalled or exceeded by that occurring in the succeeding four months.
It is concluded that an expanded plasma volume before splenectomy contributes with the hemolysis previously reported to the development of the anemia encountered in cryptogenetic splenomegaly. Expansion of the plasma volume at least contributes to the anemia which persists following splenectomy.