Platelet function defects in chronic alcoholism.

Platelet function in alcoholic patients was assessed on admission and during abstinence in hospital. On admission platelets from these patients were significantly less responsive (percentage aggregation and thromboxane A2 release) to conventional in vitro aggregating agents (adrenaline, adenosine diphosphate, and collagen) than platelets from healthy, moderate drinkers. Initially, platelet counts in platelet rich plasma tended to be low and the Simplate II bleeding times frequently prolonged. Platelet aggregation and thromboxane A2 release, however, were inhibited even in patients with normal platelet counts on admission. Platelet aggregation and thromboxane A2 release returned to normal or became hyper-responsive during two to three weeks of abstinence. Platelet counts rose during this period, the largest responses occurring in those patients with the lowest counts on admission. Bleeding times reverted to normal during abstinence and correlated significantly with changes in platelet aggregation, thromboxane A2 release, and platelet count and with the estimated ethanol consumption during the week before admission. Chronic, heavy alcohol ingestion evidently exerts an inhibitory effect on platelet function even in the absence of alcohol in the blood, and this phenomenon is reversible on abstaining. The impaired platelet function, together with the reduced platelet count, may contribute to the bleeding diathesis associated with chronic alcoholism and to the increased incidence and recurrence of gastrointestinal haemorrhage associated with excessive alcohol intake.