Thromboxane B2 (TXB2) is released in substantial quantities from aggregating platelets and metabolized during circulation to 11-dehydro TXB2 and 2,3-dinor TXB2. 11-dehydro TXB2 is one of the main plasma metabolites of TXB2 and can be used as a marker for in vivo TXA2 synthesis. The mean plasma level in human males is 0.9-4.3 pg/ml and the half life is 45-60 minutes. Urinary concentrations of 11-dehydro TXB2 are approximately 30-70 ng/mmol creatinine.