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What is a normal PSA level?

By , About.com Guide

Updated October 21, 2005

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Question: What is a normal PSA level?
The prostate gland produces a substance called PSA, or prostate specific antigen. A small amount of PSA can be found in blood, but it is mostly present in semen. A blood test is done to measure the amount of PSA.
Answer: PSA is measured by nanograms per millimeter of blood. Most men have under 4 nanograms. Anything higher can indicate prostate cancer.

According to the American Cancer Society, a PSA level between 4 and 10, indicates a 25% chance of it being prostate cancer. A PSA higher than 10, increases the chance of having prostate cancer to 50% and above.

There are several factors that can also elevate the PSA, such as:

  • ejaculation (no ejaculation at least two days prior to test)

  • PSA levels can naturally increase with age

  • inflammation of the prostate gland

  • non cancerous enlargement of the prostate


  • Also take into consideration that certain medications and herbal supplements can lower your PSA level falsely. It is important to let your physician know what meds you are taking before the test.

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