Understanding High PSA Levels: Causes & What They Mean

The male prostate produces a special protein called protein specific antigen that can indicate disease in a person, such as a tumor. However, as of 2010, doctors are still debating what PSA level would be considered too high.

Considerations

• According to the National Cancer Institute, normal PSA levels differ from person to person--what would be normal for one person would be high for another. Thus, a doctor must weigh the test result against a patient's other factors, such as medical history and age.

Identification

• For quite some time, researchers considered a PSA level above 4.0 nanograms per milliliter of blood as abnormally high under any circumstances. However, a 2004 New England Journal of Medicine study showed that a PSA level of 4.0 nanograms per milliliter equated to a 15.2 percent chance of prostate cancer, with only 2 percent of patients having the most dangerous form of prostate cancer.

Function

• PSA levels do not confirm the existence of prostate cancer, but they are useful for helping a doctor diagnose it. Repeated tests that show rising PSA levels are a symptom of prostate cancer advancing. Other tests, such as a rectal exam, are needed for a more solid diagnosis.

Significance

• Doctors now equate certain PSA levels with a likelihood of cancer. A level of 4 to 10 nanograms per milliliter indicates a 20 to 30 percent chance of prostate cancer. Anything from 10 to 20 nanograms per milliliter indicates a 75 to 90 percent chance, and anything above 20 nanograms per milliliter indicates a 90 percent or better chance.

Age

• PSA levels tend to increase as men get older. Thus, a normal PSA ratio for a 60-year-old man would be considered very high for a 40-year-old man. Certain medications, such as finasteride, can artificially cut PSA levels in half, while some procedures on the prostate, such as a biopsy, raise PSA levels.