THE RELEASE OF FREE PROSTATE-SPECIFIC ANTIGEN INTO THE CIRCULATION DURING TRANSURETHRAL RESECTION OF THE PROSTATE - KINETICS AND INTERACTION WITH SERUM PROTEASE INHIBITORS

Objective To determine the nature and extent of the release of prostat e specific antigen (PSA) and its interaction with its plasma protein-d erived inhibitors after transurethral resection of the prostate (TURF) , Materials and methods Twenty-three consecutive patients undergoing r outine TURF for benign prostatic hyperplasia had blood samples taken p re-operatively and then post-operatively at 8-hourly intervals for 24 h. Further samples were obtained at 48 and 72 h post-operatively. Seru m free and total PSA were determined by immunofluorometric assay, The major plasma protein inhibitors for PSA were also determined by immuno assay. Results The mean free and total PSA fractions increased signifi cantly post-operatively with levels greatest immediately after surgery . There was also a gradual increase in the complexed PSA fraction, rea ching a peak at 48 h, The concentration of the major serum inhibitors of PSA (alpha-1-antichymotrypsin and alpha-2-macroglobulin) also decli ned immediately after surgery. Conclusion Increases of serum total PSA in patients after TURF are caused by increases in the free PSA fracti on, The exponential decline in free PSA concentrations is consistent w ith the complexing of PSA with its protease inhibitors present in the plasma. The formation of this complex suggests that the free PSA relea sed into the circulation at the time of TURF is the enzymatically acti ve form.