A prostate-specific antigen (PSA) test measures the amount of
prostate-specific antigen in the blood. PSA is
released into a man's blood by his
prostate gland. Healthy men have low amounts of PSA in
the blood. The amount of PSA in the blood normally increases as a man's
prostate enlarges with age. PSA may increase because
of inflammation of the prostate gland (prostatitis) or
prostate cancer. An injury, a digital rectal exam, or
sexual activity (ejaculation) may also briefly raise PSA levels.
Prostate cancer often grows very slowly, without causing major problems.
Finding prostate cancer early and treating it may prevent some health
problems and reduce the risk of dying from the cancer. But some treatments for
prostate cancer can cause other problems, such as being unable to control
urination (incontinence) or erection problems (erectile dysfunction). Some men may choose not to have
a PSA test or treat prostate cancer if it is found. For example, a man older
than age 75 who has no bothersome symptoms of prostate cancer may choose not to
treat the cancer if it is found, so he would not need a PSA test.
Health Tools help you make wise health decisions or take action to improve your health.
The prostate-specific antigen (PSA) test
is done to:
Before you have a prostate-specific
antigen (PSA), tell your doctor if you have had a:
Do not ejaculate for 24 hours before your PSA blood
test, either during sex or masturbation.
Talk to your doctor about
any concerns you have regarding the need for the test, its risks, how it will
be done, or what the results will mean. To help you understand the importance
of this test, fill out the
medical test information form(What is a PDF document?).
The health professional taking a sample
of your blood will:
The blood sample is taken from a vein in
your arm. An elastic band is wrapped around your upper arm. It may feel tight.
You may feel nothing at all from the needle, or you may feel a quick sting or
Screening tests aren't perfect. They may miss some cancers, show something that looks like a tumor when it's not one, or find cancers that will never cause a problem. Since there is no way to know which ones will cause harm, cancers are usually treated. This may lead to unnecessary cancer treatments, such as surgery, chemotherapy, or radiation.
Talk to your doctor about whether you should have this screening test. It is important to know the risks of having this test and whether studies show that having the test will reduce your risk of dying from this kind of cancer.
There is very little chance of a problem from
having a blood sample taken from a vein.
A prostate-specific antigen (PSA) test
measures the amount of
prostate-specific antigen in the blood.
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
Because normal PSA levels seem to increase
with age, age-specific ranges may be used. But the use of age-specific ranges
is controversial, and some doctors prefer to use one range for all ages. For
this reason, it is important to discuss your test results with your
Men age 40–49:
nanograms per milliliter (ng/mL)
micrograms per liter (mcg/L)
Men age 50–59:
Men age 60–69:
A follow-up test that measures free prostate-specific
antigen (free PSA) may be used to see if a prostate biopsy should be done to
check for cancer. Free PSA is prostate-specific antigen that is not attached to proteins in the blood. The lower a man's free PSA level, the more likely he is to
develop prostate cancer.
Percent free PSA
Probability of cancer
More than 25%:
Reasons you may not be able to
have the test or why the results may not be helpful include:
Other Works ConsultedChernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis:
Saunders.Fischbach FT, Dunning MB III, eds. (2009).
Manual of Laboratory and Diagnostic Tests, 8th ed.
Philadelphia: Lippincott Williams and Wilkins.Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.U.S. Preventive Services Task Force (2008).
Screening for Prostate Cancer: Clinical Summary of a U.S. Preventive Services Task Force Recommendation. Rockville, MD: Agency for Healthcare Research and Quality. Available online:
May 22, 2012
E. Gregory Thompson, MD - Internal Medicine & Christopher G. Wood, MD, FACS - Urology, Oncology
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