Roles of Prothrombin Activity, Heparin-Protamine Titer and Platelet Concentration in Bleeding of Leukemia

A test for circulating "heparin-like" anticoagulants neutralizable by protamine has been studied in children with acute leukemia. Bleeding occurred with equal frequency among those with normal and those with elevated heparin-protamine titers. When the protamine titers are calculated on the basis of unit plasma volume, similar distributions of titers for both bleeding and nonbleeding leukemic individuals and identical medians for both groups are observed. The hemorrhagic diathesis in acute leukemia does not necessarily appear to be dependent on coagulation defects demonstrable by prothrombin time, although such defects often are present.

The regular association of circulating platelet levels below 50,000 to 60,000 per cu. mm. with bleeding in acute leukemia has been reaffirmed. Below this critical level, the rate of plasma coagulation is often, but not always, prolonged. Although critical thrombocytopenia appears to be essential to activation of the hemorrhagic diathesis, it seems not to be causative by itself. The relationships among bleeding, thrombocytopenia, and coagulation are discussed.