In vivo production of thromboxane and prostacyclin in patients following total hip arthroplasty.

The in vivo production of thromboxane and prostacyclin was studied by measurements of their major urinary metabolites in eight patients undergoing total hip arthroplasty. Specific methods based on gas chromatography-mass spectrometry were used to measure the urinary excretion of 2,3-dinor-TxB2 and 2,3-dinor-6-keto-PGF1 alpha. The excretion of these metabolites increased about 10-fold during the intra and immediate postoperative period and 4 days after surgery was still higher than during the preoperative period. The increased thromboxane formation reflects probable activation of platelets whereas the increased prostacyclin could be part of a vascular defense against induced thrombotic activity. These findings may have pathophysiological implications.