High PSA levels may indicate prostate cancer, prostatitis or an enlarged prostate, states WebMD. PSA levels in men naturally increase with age. In most cases, a PSA level under 4 nanograms per milliliter is considered normal, and men with this result have a low chance of prostate cancer.
Some medications may mask high PSA levels. For example, drugs such as Proscar and Avodart may cause PSA level readings to be as much as half of the actual amount, according to WebMD.
The PSA test is a blood test that measures the prostate-specific antigen secreted by the prostate gland, explains WebMD. The test is used as a cancer screening tool, and doctors may request a prostate biopsy or other diagnostic tests if PSA levels are high, states the National Cancer Institute.
Some doctors recommend testing for men over the age of 50, but the National Cancer Institute cautions that there are several risks involved with PSA testing. The PSA test may give false results. Men with low PSA levels may still have cancer, and some men with high PSA levels do not have cancer. In addition, the National Cancer Institute states that early diagnosis or prostate cancer does not necessarily improve the patient's prognosis.
PSA testing is also done after a patient has been diagnosed with prostate cancer in order to help doctors determine treatment options and success levels, states WebMD.