THE BEHAVIOUR AND SURVIVAL OF PLATELETS IN POLYCYTHÆMIA AND THROMBOCYTHÆMIA

Summary With the use of radiochromium as a label, reduced platelet survivals were demonstrated in eight of 12 patients with polycythæmia vera. A reduced platelet survival was most commonly encountered in untreated patients with active disease, when the platelet count was abnormal, and when there was an antecedent history of either hæmorrhage or thrombosis. Evidence is presented which suggests that the reduction of platelet survival in this condition is the result of an intrinsic abnormality in the platelets, rather than of the consumption of platelets in a continuous process of subliminal coagulation. Normal platelet survivals were found in three patients with congenital polycythæmia, in one patient with polycythæmia associated with chronic anoxic lung disease, and in four subjects with thrombocytosis. One patient with “hæmorrbagic” thrombocythæmia, and another with chronic myeloid leukæmia, also had reduced platelet survivals. Cross‐transfusion and surface counting studies in the latter case suggested that the platelets were being destroyed in the patient's spleen. This, in the presence of thrombocythæmia raises the possibility of a “compensatory” type of hypersplenism.