The labelled analogue of an inactive metabolite/product of Thromboxane A2 (TBXA2): a compound involved in platelet activation and aggregation in case of a wound. Urinary analysis of TXB2 accurately reflects intrarenal TXA2 synthesis while measurement of 11-dehydro TBX2 (D230555) and 2,3-dinor thromboxane metabolites gives the best estimate of systemic TXA2 secretion.