Thromboxane A2 (TXA2), produced from arachidonic acid, causes irreversible platelet aggregation and contraction of vascular and bronchial smooth muscle. TXA2 is rapidly hydrolyzed non-enzymatically to TXB2, which is then quickly metabolized to urinary metabolites for clearance by the kidneys. Urinary analysis of TXB2 accurately reflects intrarenal TXA2 synthesis, while measurement of 11-dehydro and 2,3-dinor thromboxane metabolites gives the best estimate of systemic TXA2 secretion. Cayman's Thromboxane B2 (TXB2) Express EIA is a competitive assay that provides a rapid, accurate measurement of TXB2 from plasma, urine, and cell culture supernatants. The assay typically exhibits an IC50 value (50% B/B0) of approximately 176 pg/ml and a detection limit (80% B/B0) of approximately 45 pg/ml.