THE ASA EFFECT TEST: LIfeLabs now offers a urine Test to Determine if a patient is receiving the beneficial effects of ASA
Up to a quarter of individuals who take acetylsalicylic acid (ASA) may not benefit from its anti-clotting effect. In aspirintreated patients, urinary concentrations of 11-dehydro thromboxane B2 predict future risk of myocardial infarction or cardiovascular death. The ASA Effect test measures urinary thromboxane B2 levels to identify patients who are relatively resistant to aspirin and who may benefit from additional antiplatelet therapies or treatments that more effectively block thromboxane function.
ASA is one of the most commonly used medications around the world and is known to reduce the risk of serious cardiovascular events in a broad range of high-risk patients. The primary effect of ASA on hemostasis is to acetylate platelet cyclooxygenase (COX-1) and thereby inhibit the synthesis of thromboxane A2, a powerful platelet activator.
Some 25 percent of patients have been reported to be resistant to ASA and continue to generate thromboxane A2 and thereby activate platelets. Possible mechanisms of ASA resistance include: poor compliance with ASA treatment, inadequate ASA dose, and concomitant use of other
COX inhibitors that interfere with the antiplatelet effects of ASA, increased platelet turnover, and true genetic-based “resistance” to the inhibitory effects of ASA.