Prostate-specific antigen (PSA) is produced by the cells of the prostate gland. Patients with benign prostatic hyperplasia (BPH) or prostatitis produce greater amounts of PSA. The PSA level also is determined in part by the size and weight of the prostate.

The test measures the amount of PSA in the blood in nanograms per milliliter (ng/mL). Most men have PSA levels under 4 ng/mL or lower is considered normal. Men with prostate cancer often have PSA levels higher than four, although cancer is a possibility at any PSA level. Most men with slightly elevated PSA levels do not have prostate cancer, and many men with prostate cancer have normal PSA levels. A highly elevated level may indicate the presence of cancer.

PSA in the blood may be bound molecularly to one of several proteins or may exist in a free, or unbound, state. Total PSA is the sum of the levels of both forms; free PSA measures the level of unbound PSA only. In an effort to make PSA testing more sensitive, percent free PSA is used to help quantify risk of underlying cancer.

According to published reports, men who have a prostate gland that feels normal on examination and a PSA less than four have a 15% chance of having prostate cancer. Those with a PSA between four and 10 have a 25% chance of having prostate cancer and if the PSA is higher than 10, the risk increases to 67%.

Younger patients, less than 50 years of age, tend to have smaller prostates and lower PSA values, so any elevation of the PSA in younger men above 2.5 ng/mL is a cause for concern. Older patients can have higher PSAs because of BPH, and there are age-specific valves. However, there is no safe PSA level.

Just as important as the PSA number is the trend of that number, (whether it is going up, how quickly, and over what period of time). It is important to understand that the PSA test is not perfect, and there are lots of controversies regarding PSA screening, but the American Urological Association still feels this is an important tool that can save lives. You should discuss the benefits and potential harms of PSA screening with your urologist.

PSA blood tests and DRE should be offered in all men beginning at age 40, especially African American men and those with a family history.

If your doctor is concerned that you might have prostate cancer based on either your PSA level or a rectal exam, a biopsy (a lab testing of a small amount of tissue from the prostate) will be this next step. This is the only way to positively identify the presence of cancer.

The diagnosis of cancer is confirmed only by a biopsy. Once prostate cancer is diagnosed, additional testing such as CT scan, or bone scan may be useful to adequately stage the disease.

PSA screening is done the Poughkeepsie, Fishkill, Kingston and Rhinebeck offices.