Acquired platelet dysfunction, which is common, may result from aspirin, other NSAIDs, or systemic disorders.
Acquired abnormalities of platelet function are very common. Causes include
Acquired platelet dysfunction is suspected and diagnosed when an isolated prolongation of bleeding is observed and other possible diagnoses have been eliminated. Platelet aggregation studies are unnecessary.
Aspirin, other NSAIDs, and inhibitors of the platelet P2Y12 ADP receptor (eg, clopidogrel, prasugrel, ticagrelor) may induce platelet dysfunction. Sometimes this effect is incidental (eg, when the drugs are used to relieve pain and inflammation) and sometimes therapeutic (eg, when aspirin or the P2Y12 inhibitors are used for prevention of stroke or coronary thrombosis).
Aspirin and NSAIDs prevent cyclooxygenase-mediated production of thromboxane A2. This effect can last 5 to 7 days. Aspirin modestly increases bleeding in healthy people but may markedly increase bleeding in patients with underlying platelet dysfunction or a severe coagulation disturbance (eg, patients receiving heparin, patients with severe hemophilia). Clopidogrel, prasugrel, and ticagrelor all can markedly reduce platelet function and increase bleeding.
Many disorders (eg, myeloproliferative and myelodysplastic disorders, uremia, macroglobulinemia and multiple myeloma, cirrhosis, SLE) can impair platelet function.
Uremia prolongs bleeding via unknown mechanisms. If bleeding is observed clinically, bleeding may be reduced with vigorous dialysis, cryoprecipitate administration, or desmopressin infusion. If necessary, increasing the Hb concentration to > 10 g/dL by transfusion or by giving erythropoietin also reduces bleeding.
Platelets may become dysfunctional, prolonging bleeding, as blood circulates through a pump oxygenator during cardiopulmonary bypass. The mechanism appears to be activation of fibrinolysis on the platelet surface with resultant loss of the glycoprotein Ib/IX binding site for von Willebrand factor. Regardless of platelet count, patients who bleed excessively after cardiopulmonary bypass are often transfused with platelets. Giving aprotinin (a protease inhibitor that neutralizes protease activity) during bypass may preserve platelet function and reduce the need for transfusion.
Last full review/revision October 2012 by David J. Kuter