Understanding PSA Levels

Excerpt from FC&A's The Prostate Answer Book.

Once you’re ready for your PSA test, your doctor or nurse will take a small sample of blood. It will go to a laboratory where they will measure the amount of PSA in your blood using a special procedure called immunoassay. Your results will be reported as nanograms per milliliter of blood, usually written as ng/mL

Normal PSA levels have been typically defined as being around 4 ng/mL. If you have a PSA between 4 and 10 ng/mL, the chances that you have prostate cancer are 20 to 50 percent. If your PSA level is over 10 ng/mL, you are 50 to 75 percent more likely to have prostate cancer, and if your PSA level goes over 20 ng/mL, there is a 90 percent chance you have prostate cancer.

Although normal PSA levels fall within a fairly narrow range, there’s no need to panic if yours don’t. There could be any number of reasons for a raised PSA that don’t indicate cancer.

For example, an enlarged prostate often produces more PSA, creating higher blood levels of the protein. This may also occur when infection damages the prostate lining and allows more than normal amounts of PSA to be released. A urinary tract disorder can also raise PSA levels. In addition, problems that aren’t really related to the prostate can affect PSA levels.

For example, researchers recently noted that acute viral hepatitis (inflammation of the liver caused by a virus) can also raise PSA levels. During a young man’s bout of hepatitis, his PSA levels peaked at 28 ng/mL, an amount typically assumed to be caused by cancer. If you have unexplained increases in your PSA levels, it could be a case of underlying liver disease. Low testosterone levels also appear to lower PSA levels and may even affect prostate tumors, making them undetectable during a DRE exam.

Even age and race influence PSA levels. As men age, their PSA levels tend to increase. Also, PSA levels are higher and more varied among African-American men. Based on the so-called "normal" PSA levels, over 40 percent of the cases of prostate cancer in African-American men would not be detected. Also, PSA levels are higher among African-American men with newly diagnosed prostate cancer than they are among white men.

If your PSA is higher than normal for your age and race, your doctor will probably suggest a transrectal ultrasound and possibly a biopsy.