The prostate specific antigen or PSA test is an important test to detect prostate cancer, as well as monitor the progress of prostate cancer treatment.

The prostate specific antigen blood test measures a protein that is made by the prostate gland. PSA is increased in males who have prostate cancer.

A normal PSA level is lower than 4 nanograms per milliliter (ng/ml). About one-quarter of men with borderline PSA elevations (4.1 to 10.0 ng/ml) have prostate cancer. Almost two-thirds of those with PSA levels of 10 ng/ml, or higher, have prostate cancer. Very high PSA levels suggest the presence of advanced cancer.

PSA testing is recommended annually for all men over the age of 50. If you are under 50 years old, your doctor can decide whether you require PSA testing.

Additional testing for prostate cancer may be required in the following situations:

• PSA level over 4.0 ng/ml in males over 50
• PSA level over 2.5 ng/ml in males under 50
• PSA level rises more than 20 percent in one year
• PSA level rises more than 0.75 ng/ml in one year