1. A case of thrombopathic thrombocytopenia, a variant of chronic idiopathic thrombocytopenia is described.
2. In addition to the customary studies, the prothrombin consumption test of Quick was used in a study of the physiology of the platelets.
3. The patient’s platelets were not only reduced in number but were morphologically abnormal and physiologically defective. Their abnormality was presumably related to the lack of granularity in the cytoplasm of the platelet-producing cells, namely, the megakaryocytes.
4. Because of the uniformly abnormal appearance of the patient’s platelets, the success of a transfusion of normal platelets could be readily evaluated from inspection of stained blood smears.
5. Transfusion of blood from a polycythemic donor whose platelet count was about eight times the normal level resulted in the recovery of a detectable proportion of these platelets in the patient. Possible mechanisms leading to their relatively low recovery are discussed.
6. The donor platelets survived for five to six days and retained their normal physiologic activity throughout that time.