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What is PSA?

PSA stands for prostate specific antigen, and it is actuallya certain type of glycoprotein which can be found in humans and is normallyencoded by the gene called KLK3. It is also sometimes referred to as kallikreinor gamma seminoprotein. This KLK3 belongs to the family of peptidase and itgets secreted by the epithelial cells located in the prostate gland. Its mainpurpose is to liquefy the semen after the ejaculation occurs. This processtakes place in the seminal coagulum. Another important role that PSA plays isthat it allows the sperm to swim free and it also plays an important role indissolving 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 whosuffer from prostate related medical problems such as prostate cancer usuallyhave elevated levels of PSA in their prostates. The most effective way ofmeasuring the amount of PSA in the prostate is the blood test. According tocertain statistics its predictive value is somewhere around 35 per cent. When aperson experiences gradual rising of the levels of PSA over time, that usuallyindicates either localized or metastatic prostate cancer. The normal activityof PSA is commonly well regulated in the human body, mainly by the activitiesof a kallikrein related peptidase known as KLK2 and the zinc ions. Furtheractivity is also controlled by certain variations in the pH values. When the pHvalue gets increased it also leads to the increased activity of the PSA and theinhibitory effect of the zinc ions. The vagina is characterized by a highlyacidic pH due to the presence of lactic acid. The zinc inhibition then getsreduced so that the semen can deal with the high pH acidity of the vagina andthe sperm gets released when the coagulum gets liquefied. Ever since thediscovery of the prostate-specific antigen it was surrounded with much controversy.It was discovered separately in the semen and the prostatic tissue and eachdiscovery 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 testwhich 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 DrugAdministration approximately at the same time as the digital rectal exam. Thesetests are commonly performed in men aged 50 and more in order determine thepresence of prostate cancer. The PSA test is also approved by the United StatesFood and Drug administration for use in patients who have a history of prostatecancer. In such cases, the tests are performed to check whether the cancer hasrecurred. Even though these tests are often performed in cases when the PSAlevels are elevated, there are still certain controversial limitationsassociated with them. The tests are constantly improved and validated byresearchers. These improvements are usually focused on new ways of earlydetection of prostate cancer. All sorts of prostate related medical conditionsincluding prostate cancer are rather common among older men. Out of alldifferent types of medical conditions which may affect the prostate, theinflammation of the prostate (medicinally referred to as prostatitis) andenlargement of the prostate (medicinally referred to as benign prostatichyperplasia) are the most common ones. There is still no scientific evidencethat inflammation of the prostate may lead to the development of prostatecancer, but still there are certain cases in which both conditions are present.The recommendations for screening test may vary for numerous reasons. Somedoctors encourage the screening tests only in men who are 50 or older. There arealso certain doctors who recommend screening tests in men who are at theirhighest risk between 40 and 45 years of age. There is a third group of doctorswho actually do not recommend routine screening at all. This is mainly due tothe fact the PSA screening may sometimes be related to certain potential risksbesides its obvious benefits. The factors which are commonly considered ascontributory when it comes to the development of prostate cancer are age 65 orolder, certain dietary habits, family history of the disease and so on. It isquite a peculiar fact that African American men are affected by the prostatecancer much more often than Native American or Asian men. According to certain scientificstudies, a diet which is rather high in fat may also contribute to the developmentof prostate cancer.


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

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