Prostate-Specific Antigen (PSA) Test
Reviewed
Also called: total PSA, free PSA
A prostate-specific antigen (PSA) test is a blood test that measures the level of PSA in a sample of your blood.
Specimen: blood
Why this test may be ordered
- To screen for prostate cancer before symptoms appear
- To help diagnose the cause of prostate conditions that are not cancer
- To monitor treatment for a prostate condition, including cancer
Preparation and collection
You will need to avoid having sex or masturbating for 24 hours before your PSA test. Also, certain medicines may affect your test results, so tell your provider about any medicines you take. But don't stop taking any medicines unless your provider tells you to.
A health care professional will take a blood sample from a vein in your arm, using a small needle. This usually takes less than five minutes.
There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
Understanding results
There is no specific normal or abnormal level for PSA in blood. In general, the higher your PSA level, the more likely it is that you have cancer.
- Low PSA level: It's normal to have a low level of PSA in your blood. Limitation: But it's possible to have a high PSA without prostate cancer, or a low PSA with prostate cancer. Next step: If you have questions about your results, talk with your provider.
- High PSA level: High PSA levels can mean you have prostate cancer or a prostate condition that's not cancer, such as an infection (causing prostatitis) or an enlarged prostate. Limitation: A PSA test can't show what is causing abnormal PSA levels. Next step: If your PSA levels are higher than normal, your provider may talk with you about having more tests to diagnose the cause.
- 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
Your provider will usually look at several tests results over time to get a better understanding of your condition. If you have questions about your results, talk with your provider.
- What is my risk for developing a serious type of prostate cancer?
- Is my general health good enough to have treatment for prostate cancer if it is found?
- What are the possible benefits and harms of screening, diagnosis, and treatment for me?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.
U.S. National Library of Medicine: Prostate-Specific Antigen (PSA) Test