A PSA Test measures the amount of PSA in the blood. The prostate gland produces a protein called prostate specific antigen, or PSA for short.The higher amounts of PSA found, the more likely prostate cancer is present. A high PSA level does not always mean cancer, however.
For more information, see Prostate Cancer and the Links associated with this article.
Sometimes cancer cells do not produce much PSA, and the test will be negative even when the disease is present.
If prostate cancer is diagnosed, the total PSA test may be used as a monitoring tool to help determine the effectiveness of treatment. The total PSA test and digital rectal exam (DRE) may be used to screen both asymptomatic and symptomatic men for prostate cancer. If the DRE is normal but the PSA is moderately elevated, the doctor may order a free PSA test to look at the ratio of free to total PSA. This can help to distinguish between prostate cancer and other non-cancer causes of elevated PSA. Since the total PSA test can be elevated temporarily for a variety of reasons, a doctor may order another PSA a few weeks after the first to determine if the PSA is still elevated.
Currently there is no consensus about using the PSA test to screen for prostate cancer in asymptomatic men. While prostate cancer is a relatively common type of cancer in men, it is an uncommon cause of death. Total PSA levels may be ordered at frequent intervals to monitor the change in PSA over time.
(See Prostate Cancer Screening for Adults and Adults 50 and Up.)
If a total PSA level is elevated, a doctor may order a repeat test a few weeks later to determine whether the PSA concentrations have returned to normal.
A free PSA is primarily ordered when a man has a moderately elevated total PSA. The total PSA may be ordered during treatment of men who have been diagnosed with prostate cancer to verify the effectiveness of treatment and at regular intervals after treatment to monitor for cancer recurrence.
When men in the gray zone have decreased levels of free PSA, they have a higher probability of prostate cancer; when they have elevated levels of free PSA, the risk is diminished. When the cPSA test is used as a screening tool, increased levels may indicate an increased risk of prostate cancer, while lower levels indicate a decreased risk.
PSA velocity. This is the change in PSA concentrations over time. PSA doubling time. It measures how rapidly the PSA concentration doubles.
PSA density. Age-specific PSA ranges.
During treatment for prostate cancer, the PSA level should begin to fall. Following treatment, the PSA test is performed at regular intervals to monitor the person for cancer recurrence. Prostate manipulation by biopsy or resection of the prostate will significantly elevate PSA levels. In some men, PSA may rise temporarily due to other prostate conditions, especially infection.
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