Studies of Hemostatic Mechanisms in Leukemia and Thrombocytopenia

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Abstract
Thirty-nine patients suffering from leukemia, 24 from various types of thrombocytopenia, and 3 from thrombocythemia were studied with regard to various measures of hemostatic function. In leukemia, depressions of the platelet count and the level of plasma proaccelerin were the most frequently observed abnormalities, but it was noted that neither correlated well with clinical evidence of a bleeding tendency. In thrombocytopenia, depression of the platelet count was the only frequently encountered abnormality. In thrombocythemia, a great increase in the platelet count was frequently accompanied by a relative depression in platelet function (thrombo-plastic and accelerator factors, and serotonin) and a decreased amount of plasma proaccelerin. When comparing the findings in leukemic and thrombocytopenic patients with platelet counts in the same range, the results of the tourniquet tests were normal in most leukemic patients, but abnormal in most thrombocytopenic patients; the bleeding time was prolonged in approximately 1/2 of the leukemic patients and in most of the thrombocytopenic patients. Abnormalities in clot retraction and prothrombin consumption correlated well with platelet count in both groups of patients. The level of serotonin in the serum was normal in a few of the patients with idiopathic thrombocytopenic purpura, but low in most of the other thrombocytopenic and leukemic patients. Active fibrinolysin and prolonged plasma-thrombin clotting times were observed in some of the leukemic patients. The precise cause of the hemorrhagic tendency frequently associated with leukemia is not clear. The phenomenon seems to be correlated with a deficiency of platelets, but other factors are involved in many, or even all, patients with leukemia.