Increased platelet aggregation following splenectomy in patients with myeloproliferative disease

In 30 patients with myeloproliferative disorders, decreased platelet aggregation in response to both ADP and collagen was demonstrated. The hypoaggregability was more drastic in patients with large spleens. Patients who had had splenectomy in the past showed normal platelet aggregation. In order to understand the role of the spleen in platelet function, platelet aggregation was studied in three patients with myeloproliferative disorders during the week following splenectomy and was compared to platelet aggregation in three control patients undergoing orthopedic operations. After splenectomy, platelet aggregation significantly increased, reaching a maximum after 3 to 4 days, but returned to presplenectomy values after 1 week. This is in contrast to the control patients, in whom no significant changes in platelet aggregation were observed. Our results suggest that the spleen retains or catabolizes the most hemostatically effective platelets.