July 1985

Decreased Platelet Aggregation but Increased Thromboxane A2 Generation in Polycythemia Vera

Author Affiliations

From the Departments of Pediatrics (Dr P. Mehta and Ms Ostrowski), Medicine (Dr J. Mehta), and Anatomy (Dr Ross and Mr Player), University of Florida College of Medicine, and the Veterans Administration Medical Center (Dr J. Mehta), Gainesville.

Arch Intern Med. 1985;145(7):1225-1227. doi:10.1001/archinte.1985.00360070103016

• Patients with polycythemia vera have been described to have hemorrhagic as well as thrombotic tendencies. In a patient with polycythemia vera and angina pectoris, we observed markedly decreased platelet aggregation response to epinephrine but increased platelet and whole-blood thromboxane A2 generation compared with normal subjects. Electron microscopy mostly showed partially activated forms of platelets, which may account for decreased aggregation response in vitro and hemorrhagic tendencies. Young and large platelets found in this disease, however, can generate large amounts of vasoconstrictor and platelet proaggregatory prostanoid thromboxane A2 in response to endogenous thrombin, which may be a basis for thrombotic tendencies.

(Arch Intern Med 1985;145:1225-1227)