Question

What does a PSA blood test check?

Answer

This blood test checks prostate specific antigen (PSA), a protein made by the prostate gland. The exact function of PSA is unclear. However, it is known that PSA helps to keep semen in a liquid state. Generally, men will have low levels of PSA in the blood. As men age and the prostate gland normally enlarges, PSA level tends to rise. This generally occurs around age 50 (or late 40s) when the prostate undergoes another growth period.

A man's PSA level may be elevated when disease is present in the prostate. Examples of conditions in which high PSA levels may be present include prostate cancer, noncancerous enlargement of the prostate (for example, benign prostatic hyperplasia), inflammation of the prostate, or infection of the prostate.

There may be certain cases where the level of PSA is normal or low, even though disease may be present. Physicians may choose to perform additional tests, including DRE (digital rectal exam) for additional screening of the prostate.

Read about prostate cancer in our Health Encyclopedia.

Learn about enlarged prostate.

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