The clinical relevance of platelet aggregation study in myeloproliferative disorders

30 unselected patients with various entities of the myeloproliferative syndrome were entered into a prospective study to evaluate the relationship between platelet aggregation abnormalities and hemostatic complications and the role of aggregation study in myeloproliferative disorders. 21 patients showed impaired collagen-induced aggregation and absent second phase epinephrine-induced response. 6 of these patients had bleeding manifestations. 4 patients hyperaggregated with ADP, collagen, epinephrine and arachidonic acid. Of these, 3 had thrombotic complications as their initial presentation. In the 6-40 months follow-up no new cases of bleeding or thromboembolic phenomena were encountered among the remaining patients. In 3 patients aggregation abnormalities heralded the specific myeloproliferative disorder by months or years. We conclude from this study that routine platelet aggregation study in classical myeloproliferative disorders is unwarranted as it is costly and does not improve the diagnostic accuracy nor yield any predictive information concerning the tendency to bleed. It is useful as an accessory investigative tool in the atypical or early myeloproliferative patient whose clinical features, blood and marrow findings although suggestive are not diagnostic of a specific myeloproliferative entity.