Abnormalities in platelet function and morphology in a case of thrombocythemia.

A patient with "life-long" bleeding problems and thrombocythemia had normal results on routine coagulation and fibrinolysis tests, but platelet function tests, including bleeding time, platelet adhesiveness, aggregation, and uptake and release of labeled serotonin were markedly altered. In addition, several types of ultrastructural abnormalities not reported previously were observed in some of the patient's platelets. The relationship between thrombocythemia, platelet dysfunction, and abnormal morphology is discussed.