Soybean Phosphatides in Prothrombin-Consumption and Thromboplastin-Generation Tests: Their Use in Recognizing “Thrombasthenic Hemophilia”

Abstract

A stable preparation of commercially available soybean extract (Inosithin) can be substituted for platelets in the thromboplastin-generation test. This substitution converts the method from a research test to a potentially routine one in the coagulation laboratory. The addition of Inosithin to freshly drawn whole blood in the performance of the prothrombin-consumption test furnishes a simple means of distinguishing deficiencies of platelets from abnormalities of coagulation not caused by changes in platelets. The abnormal consumption of prothrombin in the various types of hemophilia is not altered by the addition of Inosithin, whereas its addition does correct this abnormality in thrombocytopenia or thrombasthenia. A sex difference in the coagulability of blood usually was observed in the thromboplastin-generation test. When the serum for this test was obtained from women, the shortest clot time averaged 1.3 sec. longer than that when men''s serum was used, and the time of incubation required to reach the shortest clot time averaged 2 min. longer in the case of women. An unexpected defect in the serum reagent was observed in the thromboplastin generation test in most patients who had thrombocytopenia or thrombasthenia. Although this abnormality was generally mild, it could furnish trouble in the diagnosis of a deficiency of plasma thromboplastin component or of plasma thromboplastin antecedent from the thromboplastin-generation test alone. A combination of defects, namely, qualitative platelet insufficiency plus a plasmatic error in the thromboplastin-generation test, was recognized in 5 patients (2 men and 3 women), including a mother and daughter. This is not apparently the same as vascular hemophilia, in which a deficiency of antihemophilic globulin is associated with a vascular defect. The authors have designated this previously undefined abnormality as "thrombasthenic hemophilia".