Laboratory monitoring of coagulation and anticoagulation includes testing of platelet function. Which of the following statements is/are true concerning tests of platelet function?

a. A platelet count of 50,000/µL or more usually ensures hemostasis

c. Aspirin therapy can be associated with a bleeding time in the range of 8–15 minutes

Tests of platelet function include peripheral platelet counts, bleeding times, and platelet aggregation. Usually, a platelet count of 50,000/mL or more ensures adequate hemostasis, whereas counts less than 10,000/mL are dangerous and may lead to spontaneous bleeding. Bleeding time performed by observing the clotting of blood induced with a small needle stick, assesses the ability of platelets to perform hemostatic plugs and are usually shorter than eight minutes. A bleeding time between 8 and 15 minutes most often reflects a low plasma level of Von Willebrand’s Factor or the use of antiplatelet drugs. A bleeding time greater than 15 minutes is clearly prolonged and indicates severe platelet functional impairment. Platelet aggregation studies involve the use of a number of different agonists. Although a relatively straightforward technique, platelet aggregation is not available in most laboratories, probably because of the observer-dependent nature of the test.