Platelet amino acid levels in essential thrombocytosis.

By RALPH L. NACHMAN, HERBERT I. HoRowrrz AND RICHARD T. SILVER E SSENTIAL THROMBOCYTOSIS is a disorder of unknown etiology characterized by a marked increase in the number of circulating platelets, and max’ l)C related to the myeloproliferative diseases.1 In the course of this condition, many patients develop hemorrhagic and/or thrombotic complicalions, which may result from an abnormal number of platelets, from a qualitative defect in platelets or from t combination of both factors. If the platelets in this disorder are truly defective, the abnormality might be a consequence of deranged levels of certain intracellular constituents. In order to evaluate this possibility, the intraplatelet free amino acid composition was studied. We have also studied the pseudohyperkalemic phenomenon which represents a spurious elevation of serum potassium levels owing to potassium release from platelets when whole blood containing increased numbers of platelets clots in vitro. In addition, platelet factor 3 availability was evaluated in the thromboplastin generation test.