Prostate specific antigen (PSA), a protein produced by the prostate gland in men, is used as a tumor marker. PSA is elevated in a number of conditions affecting the prostate, however, making it a less than ideal indicator of prostate cancer.
The levels of PSA are determined by a simple blood test and are elevated in prostate cancer, benign prostatic hyperplasia (BPH) and prostatitis.
Prostate Cancer
PSA is used primarily as a screening test for prostate cancer. The test is combined with a digital rectal examination (DRE) performed by a doctor. An elevated PSA value may suggest the presence of cancer in the prostate. If the DRE also suggests cancer, then a prostate biopsy is done. The normal range for PSA is 0-4.0 ng/dL. Any value higher than 4.0 ng/dL is considered abnormal and warrants further investigation. However, some doctors will investigate patients with PSA above 2.5 ng/dL based on race or family history of the disease, as these persons are at an increased risk of developing prostate cancer.
Benign Prostatic Hyperplasia (BPH)
This disease, also called prostatic hyperplasia, is a fairly common condition in men over 50 years of age. BPH is a natural phenomenon that will affect the majority of men during the later decades in life. It is a gradual enlargement of the prostate, which normally leads to problems urinating. It often results in a mild elevation of PSA. Unfortunately, the PSA value cannot differentiate between BPH and prostate cancer, and as such, a biopsy of the prostate is usually done to make the diagnosis.
Prostatitis
Prostatitis is inflammation of the prostate usually as the result of a bacterial infection. This infection is often acquired through sexual intercourse and may cause a transient rise in the PSA value. The PSA value returns to normal after the infection has resolved. This elevation in PSA can be seen in men of any age once they are sexually active.
References
- "Sabiston Textbook of Surgery"; Townsend Jr., C et al.; 2008
- "Washington Manual of Surgery"; Doherty, G.M. et al; 2002
