Uracil mustard in the treatment of thrombocytosis.

Uracil mustard was used for the treatment of thrombocytosis in 14 patients, eight who had polycythemia vera and six who had essential thrombocytosis. Intermittent treatment with 1 to 2 mg/day for 14 days was used for most patients, and continuous treatment was used for three patients. The nadir of the platelet count occurred during a mean period of five to seven weeks, and the mean duration between courses was seven months. The drug selectively depressed the platelet count, with a minimal effect on leukocytes and erythrocytes. Uracil mustard is an effective drug for the control of thrombocytosis.