Prostate specific antigen (PSA) is a protein which comes from the prostate gland. PSA is measured for increased levels in the blood to help identify possible health issues in a man. Common reasons to have a PSA test is for the detection of prostate cancer, prostatitis, prostate infection, urinary tract infection, and benign prostatic hyperplasia (BPH). Testing for PSA is done through blood tests and is a routine screening that should be done in all men over the ago of 50. Since normally PSA levels in the blood are low testing requires special sensitive equipment to detect elevated levels.

The range for normal levels of PSA is measured up to 4 nanograms per milliliter. While it is normal for PSA levels to increase as men get older any higher levels than 4.5 could indicate the threat of cancer. This is why PSA is so commonly heard when talking about prostate cancer. High PSA alone does not mean someone has cancer as it is also an indicator for other conditions. Many men with prostate cancer do not have a high PSA. Roughly 2 out of 3 men with a high PSA do not have prostate cancer. If PSA is elevated to an abnormal level, especially if it has been monitored routinely over the years a biopsy may be ordered. The biopsy will definitively show if any cancer cells are present.

PSA is used as an early detector of prostate cancer. The PSA test is a step forward from previous detection methods of prostate cancer which involved a rectal exam. An enlarged prostate detected through a rectal exam usually meant a more advanced stage of prostate cancer. The PSA is a welcomed advance in the early detection and screening of prostate cancer.