The prostate is an exocrine gland and PSA is produced by both normal and malignant prostate cells. PSA is normally disposed of through the prostatic ducts and urethra in the semen. Normally, only small amounts of PSA diffuse back into the circulation. PSA elevations occur as a result of disruption of the normal glandular structure of the prostate that allows PSA to diffuse back into the prostatic circulation as occurs with cancer. An elevated PSA suggests the presence of prostate cancer. However, PSA elevations are not specific for cancer. PSA can be elevated in the presence of prostatitis, an enlarged prostate, or after lower urinary tract instrumentation, prostate biopsy, or surgery. Bicycling has also been shown to elevate PSA. A routine DRE, however, does not cause falsely elevated PSA values. An abnormal PSA level deserves investigation, usually by transrectal ultrasound-guided
prostate biopsy or at a minimum, repeat testing. PSA measurement should be avoided if urinary tract infection is suspected.