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What is PSA?

PSA stands for prostate specific antigen, and it is actually a certain type of glycoprotein which can be found in humans and is normally encoded by the gene called KLK3. It is also sometimes referred to as kallikrein or gamma seminoprotein. This KLK3 belongs to the family of peptidase and it gets secreted by the epithelial cells located in the prostate gland. Its main purpose is to liquefy the semen after the ejaculation occurs. This process takes place in the seminal coagulum. Another important role that PSA plays is that it allows the sperm to swim free and it also plays an important role in dissolving the cervical mucus. By doing so it allows the sperm to enter freely. Healthy men have small quantities of PSA in their prostates, while those who suffer from prostate related medical problems such as prostate cancer usually have elevated levels of PSA in their prostates. The most effective way of measuring the amount of PSA in the prostate is the blood test. According to certain statistics its predictive value is somewhere around 35 per cent. When a person experiences gradual rising of the levels of PSA over time, that usually indicates either localized or metastatic prostate cancer. The normal activity of PSA is commonly well regulated in the human body, mainly by the activities of a kallikrein related peptidase known as KLK2 and the zinc ions. Further activity is also controlled by certain variations in the pH values. When the pH value gets increased it also leads to the increased activity of the PSA and the inhibitory effect of the zinc ions. The vagina is characterized by a highly acidic pH due to the presence of lactic acid. The zinc inhibition then gets reduced so that the semen can deal with the high pH acidity of the vagina and the sperm gets released when the coagulum gets liquefied. Ever since the discovery of the prostate-specific antigen it was surrounded with much controversy. It was discovered separately in the semen and the prostatic tissue and each discovery gave it another name, so that is where the controversies begin.

Prostate-Specific Antigen Test

The prostate specific antigen test is a certain type of test which is intended to measure the levels of PSA in the blood of the patient. This type of test has been approved by the United States Food and Drug Administration approximately at the same time as the digital rectal exam. These tests are commonly performed in men aged 50 and more in order determine the presence of prostate cancer. The PSA test is also approved by the United States Food and Drug administration for use in patients who have a history of prostate cancer. In such cases, the tests are performed to check whether the cancer has recurred. Even though these tests are often performed in cases when the PSA levels are elevated, there are still certain controversial limitations associated with them. The tests are constantly improved and validated by researchers. These improvements are usually focused on new ways of early detection of prostate cancer. All sorts of prostate related medical conditions including prostate cancer are rather common among older men. Out of all different types of medical conditions which may affect the prostate, the inflammation of the prostate (medicinally referred to as prostatitis) and enlargement of the prostate (medicinally referred to as benign prostatic hyperplasia) are the most common ones. There is still no scientific evidence that inflammation of the prostate may lead to the development of prostate cancer, but still there are certain cases in which both conditions are present. The recommendations for screening test may vary for numerous reasons. Some doctors encourage the screening tests only in men who are 50 or older. There are also certain doctors who recommend screening tests in men who are at their highest risk between 40 and 45 years of age. There is a third group of doctors who actually do not recommend routine screening at all. This is mainly due to the fact the PSA screening may sometimes be related to certain potential risks besides its obvious benefits. The factors which are commonly considered as contributory when it comes to the development of prostate cancer are age 65 or older, certain dietary habits, family history of the disease and so on. It is quite a peculiar fact that African American men are affected by the prostate cancer much more often than Native American or Asian men. According to certain scientific studies, a diet which is rather high in fat may also contribute to the development of prostate cancer.


The results of the PSA test are usually shown in nanograms of PSA per milliliter of blood. One should know that there are no specific normal or abnormal levels of PSA, due to various factors which may cause the levels to fluctuate.

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