Prostate-Specific Antigen (PSA) Screen, Serum
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Prostate-specific antigen (PSA) is a glycoprotein that is produced by the prostate gland, the lining of the urethra, and the bulbourethral gland. Normally, very little PSA is secreted in the blood. Increases in glandular size and tissue damage caused by benign prostatic hypertrophy, prostatitis, or prostate cancer may increase circulating PSA levels.
In patients with previously diagnosed prostate cancer, PSA testing is advocated as an early indicator of tumor recurrence and as an indicator of response to therapy. The role of PSA in early detection of prostate cancer is controversial. The American Cancer Society recommends annual examination with digital rectal examination and serum PSA beginning at age 50, and also for those men with a life expectancy of at least 10 years after detection of prostate cancer. For men in high-risk groups, such as African Americans or men with a first-degree relative diagnosed at a younger age, testing should begin at a younger age. It is generally recommended that information be provided to patients about the benefits and limitations of testing and treatment so they can make informed decisions.
Monitoring patients with a history of prostate cancer as an early indicator of recurrence and response to treatment
Prostate cancer screening
Prostate-specific antigen (PSA) values are reported with the 95th percentile limits by decade of age. These reference limits include men with benign prostatic hyperplasia. They exclude all cases with proven cancer.
PSA values exceeding the age-specific limits are suspicious for prostate disease, but further testing, such as prostate biopsy, is needed to diagnose prostate pathology.
The minimal reporting value is 0.1 ng/mL. Values >0.2 ng/mL are considered evidence of biochemical recurrence of cancer in men after prostatectomy.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Serum markers are not specific for malignancy, and values may vary by method. When age is not supplied, the results cannot be flagged as high or low.
Digital rectal examination generally does not increase normal prostate-specific antigen (PSA) values. However, cystoscopy, urethral instrumentation, and prostate biopsy may increase PSA levels.
Some patients who have been exposed to animal antigens, either in the environment or as part of treatment or imaging procedure, may have circulating anti-animal antibodies present. These antibodies may interfere with the assay reagents to produce unreliable results.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
PSA Upper Limit (ng/mL)
< or =2.0
< or =2.5
< or =3.5
< or =4.5
< or =6.5
> or =80
< or =7.2
Females: not applicable
Clinical References Provides recommendations for further in-depth reading of a clinical nature
1. Oesterling JE, Jacobsen SJ, Chute CG, et al: Serum prostate-specific antigen in a community-based population of healthy men. JAMA 1993 Aug 18;270:860-864
2. Smith RA, Cokkinides V, von Eschenbach A, et al: American Cancer Society guidelines for the early detection of cancer. CA Cancer J Clin 2002;52:8-22
3. Barry MJ, Albertsen PC, Bagshaw MA, et al: Outcomes for men with clinically nonmetastatic prostate carcinoma managed with radical prostatectomy, external beam radiotherapy, or expectant management: a retrospective analysis. Cancer 2001 June 15;91(12):2302-2314
4. Blute ML, Bergstralh EJ, Scherer BG, et al: Use of Gleason score, prostate specific antigen, seminal vesicle and margin status to predict biochemical failure after radical prostatectomy. J Urol 2001 January;165(1):119-125