Prostate-Specific Antigen (PSA)
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
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.
Free prostate-specific antigen (fPSA)2
Percent free PSA
Probability of cancer
More than 25%:
What Affects the Test
Reasons you may not be able to
have the test or why the results may not be helpful include: