14-07: Acquired Disorders of Platelet Function

Platelet dysfunction is more commonly acquired than inherited; the widespread use of platelet-altering medications accounts for most of the cases of qualitative defects (eTable 14–2). In cases where platelet function is irreversibly altered, platelet inhibition typically recovers within 7–9 days following discontinuation of the drug, which is the time it takes to replace all of the impaired platelets with newly produced platelets. In cases where platelet function is non-irreversibly affected, platelet inhibition recovers with clearance of the drug from the system. Transfusion of platelets may be required if clinically significant bleeding is present.

Laboratory manifestations of aspirin toxicity include a prolonged epinephrine cartridge closure time in the platelet function analyzer (PFA)-100 system, or a decreased aggregation to low-dose collagen and thrombin (and preserved aggregation in response to high-dose collagen and thrombin) on platelet aggregation studies. Abnormal platelet aggregation studies may be observed in the setting of qualitative platelet defects induced by other conditions, but specific defects vary considerably.