Platelet Production Rate in Polycythemia Vera After Myelosuppressive Therapy

In nine cases of polycythemia vera (PV) treated with myelosuppressive agents and considered to be in remission the platelet production rate has been determined. Six of them did not have splenomegaly; their values for platelet production rate were within the range of a control group consisting of hematologically normal subjects. In the remaining three subjects with splenomegaly the platelet production rate was above normal. Four of the nine subjects were studied twice, before and after myelosuppressive therapy, and in all of them a considerable fall in platelet production rate was observed after myelosuppression. It is concluded that in PV the platelet production rate after myelosuppressive therapy cannot be evaluated from the peripheral platelet count alone. If splenomegaly persists after remission induced by myelosuppressive drugs, the platelet production rate is likely to be considerably increased, even though the peripheral platelet count has fallen to values within normal limits.