The normal automated platelet count in adults is approximately 150,000 to 400,000/µL. The peripheral blood smear should be examined in specimens with abnormal platelet counts or size. Platelet aggregation is the most detailed overall platelet function test.
Von Willebrand disease (vWD) is a factor deficiency that imparts clinical features of platelet dysfunction because of the central role of von Willebrand factor (vWF) in cross-linking activated platelets to form the platelet plug. Initial testing for vWD should include the vWF antigen level, vWF activity level, and a factor VIII activity level for comparison with vWF.