Qualitative platelet defects in chronic myeloproliferative disorders: evidence for reduced ATP secretion.

19 consecutive untreated patients with chronic myeloproliferative disorders and thrombocytosis were subjected to comprehensive platelet function tests including platelet aggregometry. 12 patients had essential thrombocythaemia (ET) and 7 patients had polycythaemia vera (PV). Bleeding time was normal. Arachidonic acid, collagen and ristocetin aggregation were abnormal only in a minority of patients, whereas ADP aggregation was impaired in 16 out of 19 patients. The most conspicuous findings were abolished second-wave adrenalin aggregation, increased ADP aggregation threshold, and markedly reduced ATP secretion during collagen-induced aggregation. This triad of qualitative platelet defects seems to be a good diagnostic marker of chronic myeloproliferative disease with thrombocytosis.