Measurement of Thromboxane Biosynthesis in Health and Disease

Thromboxane (TX) A(2) is a chemically unstable lipid mediator involved in several pathophysiologic processes, including primary hemostasis, atherothrombosis, inflammation, and cancer. In human platelets, TXA(2) is the major arachidonic acid derivative via the cyclooxygenase (COX)-1 pathway. Assessment of platelet TXA(2) biosynthesis can be performed ex vivo through measurement of serum TXB2, an index of platelet COX-1 activity, as well as in vivo through measurement of urinary enzymatic metabolites, a non-invasive index of platelet activation. This article reviews the main findings of four decades of clinical investigation based on these analytical approaches, focusing on the measurement of TXA(2) metabolites to characterize the pathophysiologic role of transiently or persistently enhanced platelet activation and to describe the clinical pharmacology of COX-1 inhibition in health and disease.