Prostate-Specific Antigen (PSA) Test
Reviewed
A blood test that measures the level of prostate-specific antigen (PSA), a protein made by the prostate. It is used to screen for prostate cancer and to help diagnose or monitor prostate conditions. The test cannot distinguish between cancer and noncancerous causes of elevated PSA.
Preparation and collection
Avoid having sex or masturbating for 24 hours before the test, as releasing semen can increase PSA levels and affect accuracy. Tell your provider about any medicines you take, but do not stop taking any unless instructed.
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- A PSA test cannot distinguish between abnormal PSA levels from prostate cancer and noncancerous conditions.
- If PSA is high, a prostate biopsy is the only way to find out if the cause is cancer; biopsies have possible harms (bleeding, infection, difficulty urinating).
- PSA screening may lead to finding and treating prostate cancer that would never have affected your health, and treatment may cause serious harms such as erectile dysfunction, urinary incontinence, or bowel incontinence.
- It can be difficult to tell the difference between slow-growing cancers and those likely to spread.
What to do next
If you have questions about your results, talk with your provider. For screening, discuss your risk, general health, and preferences to decide if PSA testing is right for you.
Evidence source
U.S. National Library of Medicine: Prostate-Specific Antigen (PSA) Test