True about PSA is all except

Prostate-specific antigen (PSA) is a glycoprotein that is a serine protease.Its function may be to facilitate liquefaction of semen, but it is a marker for prostatic disease.The levels increase with age, with prostate cancer and with BPH. There are age-related values but, in general, in men aged 50-69 years, a level of about 3-4 ng/mL would prompt a discussion about the need for prostate biopsy Its level in men with metastatic prostate cancer is usually increased to >30 ng/mL and falls to low levels after successful androgen ablation. Men with locally confined prostate cancer usually have serum PSA levels <10-15 ng/mL.Finasteride and dutasteride, which are used to treatBPH--lower a man's PSA levelPSA is a useful tumour marker in the postsurgery setting, where a supersensitive assay, with sensitivity to 0.02 ng/mL, facilitates early detection of biochemical recurrence.Bailey and Love 27e pg: 1457