Thromboxane A2 (TxA2) is a prostaglandin metabolite that is metabolically derived from arachidonic acid (AA) via the action of cyclooxygenases (COX1 in platelets and COX2 in monocytes and endothelial cells). TxA2 is a vasoactive agent that regulates blood flow and blood pressure. Additionally, it acts as a pro-thrombotic agent that promotes the activation and aggregation of platelets. However, TxA2 is highly unstable with a short half-life (20-30 secs). It is readily converted to a stable metabolite thromboxane B2, which further undergoes dehydrogenation to form 11-dehydro thromboxane B2 (11dhTxB2). 11dhTxB2 is excreted in urine and has a longer half-life than TxA2. The metabolite is unaffected by the ex vivo platelet activation and other pre-analytical variables and hence is a valid biomarker to determine platelet activity. 11dhTxB2 is found to be elevated in multiple atherothrombotic diseases. Additionally, an elevated level of 11dhTxB2 in urine indicates aspirin resistance in patients receiving antiplatelet aspirin therapy.
In 158 mM Tris, 0.1 M Citric acid, pH 6.1