Prostate-Specific Antigen (PSA) Test

A prostate-specific antigen (PSA) test and a digital rectal exam (DRE) are often helpful in diagnosing prostate cancer in men who have no symptoms. PSA is a protein produced by the cells of the prostate gland, a male reproductive gland that makes the fluid that carries sperm during ejaculation. A healthy prostate is a little larger than a walnut. It is located just below the bladder and surrounds the urethra, the tube that allows urine to pass out of the body.

PSA is released along with semen during ejaculation; some PSA makes its way into the bloodstream. A simple blood test is used to measure the level of PSA in the bloodstream.

PSA Test Timetable

For men, the American Cancer Society recommends an annual PSA at:

  • Age 50 for all men who do not have major health problems
  • Age 45 for men at high risk for prostate cancer. This includes African-American men and men with a first-degree relative diagnosed with prostate cancer at an early age (younger than age 65)
  • Age 40 for men with very high-risk, including more than one first-degree relative diagnosed with prostate cancer at an early age.

Check with your primary care physician or urologist to determine a timetable that's right for you and your family history.

Test Results and What They Mean

The National Cancer Institute at the National Institutes of Health states:

  • There is no specific normal or abnormal level of PSA in the blood.  In the past, most doctors considered PSA levels of 4.0 ng/mL and lower as normal.
  • However, more recent studies have shown that some men with PSA levels below 4.0 ng/mL have prostate cancer and that many men with higher levels do not have prostate cancer.
  • Various factors can cause a man’s PSA level to fluctuate, ranging from having a urinary tract infection to taking medication to treat BHP.
  • Although expert opinions vary, there is no clear consensus regarding the optimal PSA threshold for recommending a prostate biopsy for men of any racial or ethnic group.
  • In general, the higher a man’s PSA level, the more likely it is that he has prostate cancer.  Moreover, continuous rise in a man’s PSA level over time may also be a sign of prostate cancer.

Does an Elevated PSA Level Always Mean Cancer?

Though there is always some risk of the test resulting in a "false negative" (a normal PSA reading when cancer is actually present), an increase in PSA levels may be caused by:

  • a prostate gland biopsy
  • a resection of the prostate
  • rigorous physical activity related to the prostate (i.e. bicycle riding)
  • excessive doses of chemotherapeutic drugs
  • prostatitis (inflammation of the prostate gland)
  • enlarged prostate (benign prostatic hyperplasia - BPA)
  • the test returns an elevated PSA level that, after further testing, reveals there is no underlying condition

Treating Increased PSA Levels

A PSA test is a biological marker or sign of an underlying condition. Physicians conduct further tests to determine the cause of the elevated PSA and treat the underlying condition. For example, if the increased PSA level is caused by prostate cancer, physicians treat the cancer.

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