Thrombo‐embolism and Increased Platelet Adhesiveness in Post‐splenectomy Thrombocytosis

SUMMARY Platelet count data have been obtained from patients suffering from various types of hereditary hæmolytic anæmia, sideroblastic anæmia and thalassæmia, and from hæmatologically normal controls. One‐third of the patients studied had been subjected to splenectomy. Patients with persistent anæmia after splenectomy developed post‐splenectomy thrombocytosis. The percentage of platelets which were adhesive was increased after splenectomy irrespective of whether anæmia and thrombocytosis persisted. Six of the 25 patients with persistent post‐splenectomy thrombocytosis developed thrombo‐embolic complications. On the other hand, signs or symptoms of thrombo‐embolism were not observed in any of 21 patients who had normal platelet counts after splenectomy, or in 72 patients suffering from similar disorders who had not been subjected to splenectomy. The cause of the high incidence of thrombo‐embolic complications in patients with continuing anæmia after splenectomy is not completely understood, but it seems likely that thrombocytosis and increased platelet adhesiveness may play a part.