AspirinWorks is an FDA-approved kit that is used to determine aspirin effect. The test measures the thromboxane metabolite, 11-dehydrothromboxane B2 (11-dhTxB2) in a urine sample.
Purified mouse monoclonal antibody and purified 11-dhTxB2 conjugated to alkaline phosphatase compete for binding with the 11-dhTxB2 present in the urine sample. The intensity of color development following addition of chromogenic substrate is inversely proportional to the concentration of 11-dhTxB2 in the urine sample. Results (pg/mL) are calculated against a reference curve. Final patient results are normalized by urine creatinine concentration, as measured by a separate assay. A low level of 11-dhTxB2 in the urine is associated with successful aspirin therapy (aspirin is working to reduce thromboxane production). High levels of the biomarker may mean that the dosage of aspirin is not effective or a patient is aspirin-resistant.