The prostate specific antigen is a protein produced in the prostate gland. According to the National Cancer Institute, it is normal for healthy men to have low levels of PSA in their blood. An increase in the PSA level happens with age, but can also indicate prostate cancer. Men older than 40 should have PSA values no higher than 2.5 nanograms per milliliter. For those over 70, for instance, the normal levels are up to 6.5 nanograms per milliliter, reports the Association for International Cancer Research. PSA tests, which are used to detect prostate cancer, measures the amount of PSA through the analysis of a blood sample.
PSA Velocity Test
This test analyzes the change in PSA levels over a period of time. The patient submits to several PSA tests during a year or two. Then, the rate of increase in the PSA level is calculated. A sharp rise in the PSA level may be a sign of an aggressive prostrate cancer. A study performed at the Johns Hopkins School of Medicine and published in the "Journal of the National Cancer Institute" in 2006 concluded that men with PSA velocity results above 0.35 nanograms per milliliter were more at risk of dying from prostate cancer than men who had lower values.
Free Versus Attached PSA Test
In the bloodstream, PSA can circulate freely or attached to a protein. PSA tests can analyze the molecule in both forms. Free PSA is often used to detect the type of tumor. Patients with benign conditions often have higher levels of free PSA, while men suffering from malignant cancers have higher quantities of attached PSA. Generally, if the PSA level in a patient is high, but his free PSA is low, the diagnosis of cancer is probable, according to the National Cancer Institute.
PSA Density Test
The PSA density test indicates the ratio between PSA levels and the size of the prostate gland, which is determined with ultrasound. The PSA density test is effective in distinguishing between cancer and benign prostatic hyperplasia, more common in elderly men. This method is not the most accurate, as it analyzes PSA levels in relation with prostate size.
Alteration of PSA Cutoff Level Test
Instead of using the standard 4.0 nanograms per milliliter as normal for men over 50 years of age, this test lowers the PSA normal levels to 2.5 or 3.0 nanograms per milliliter. By this method, PSA measurements above 2.5 or 3.0 can indicate a sign of early cancer development. However, this method's disadvantage is that it can increase over-diagnosis and false-positive test results.
Tags: nanograms milliliter, Cancer Institute, National Cancer, National Cancer Institute, prostate cancer, density test, have higher
