Aspirin Resistant (11-Dehydrothromboxane B2)

Aspirin (which inhibits platelet cyclo-oxygenase) reduces the risk of thrombosis in cardiovascular disease by impairing platelet function. Patients who do not respond to the platelet inhibitory effects of aspirin are designated as "ASPIRIN RESISTANT". The measurement of 11-DEHYDROTHROMBOXANE B2 in urine (the principal metabolite of platelet cyclo-oxygenase derived thromboxane B2) indicates lack of aspirin responsiveness.

Studies have found that between 5 percent and 45 percent of patients have this problem, but doctors do not routinely test for it. Increasing degrees of aspirin resistance may correlate independently with increasing risk of cardiovascular events. Aspirin resistance can be detected by laboratory tests of platelet thromboxane A2 production or platelet function that depend on platelet thromboxane production. Knowing if you’re aspirin resistant could be potentially lifesaving.