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What is Prostate-Specific Antigen?

Emma Lloyd
Emma Lloyd

Prostate-specific antigen (PSA) is a protein that is produced by healthy prostate cells in men. The protein produced in the prostate and is secreted in the semen during ejaculation. A blood or urine test measuring levels of prostate-specific antigen is used by doctors as a means of examining a man’s prostate health, in conjunction with other methods of evaluation. The protein was first characterized in the 1970s, and the PSA blood test was developed in the 1980s. The first commercial PSA blood test was released in 1986.

Prostate-specific antigen is a type of protein called a glycoprotein, which means that it contains a type of sugar chain called a glycan. This protein is produced by the prostate gland for inclusion in semen, the white fluid ejected from the penis during ejaculation. PSA, which is also known as seminin and seminoprotein, improves sperm motility by liquefying semen. In addition, the protein helps to dissolve the cap of mucus that is present in the cervix, which allows sperm to enter the uterus.

A PSA blood screening will require a blood sample.
A PSA blood screening will require a blood sample.

Since the discovery and characterization of the protein in the 1960s and 1970s, it has been made clear that the common name for the protein, prostate-specific antigen, is actually inaccurate. This is because the protein can be found in other tissues of the body, and even in women. In addition to the prostate gland and semen, PSA has also been found in female ejaculate, amniotic fluid, breast milk, breast tissue and the salivary glands. Despite this, the PSA test is still valid for the purposes of evaluating prostate health because levels of the protein are elevated in men who have prostate cancer and other prostate-related conditions.

The prostate-specific antigen level will increase with an enlarged prostate.
The prostate-specific antigen level will increase with an enlarged prostate.

There is some controversy regarding the use of the prostate-specific antigen test for evaluating prostate health. One reason is because elevated levels of PSA are not caused only by prostate cancer. Only about one-third of men who have a positive PSA test actually have prostate cancer. The prostate naturally enlarges with age, and other urogenital diseases can also cause prostate enlargement, so other tests such as physical examination and ultrasound are used in addition to the PSA blood test to make an accurate diagnosis.

PSA levels are elevated in men who have prostate cancer.
PSA levels are elevated in men who have prostate cancer.

Another aspect of the controversy is that some studies indicate that the PSA screening test is not useful for reducing mortality because of prostate cancer, and that the long-term benefits for patients are uncertain. These studies have concluded that extensive PSA screening results in unnecessary treatment for non-existent prostate problems, leading to chronic problems such as infection, erectile dysfunction and urinary incontinence. Many public and private medical organizations acknowledge these issues and suggest that men talk with their doctors about PSA screening to weigh the risks and benefits.

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    • A PSA blood screening will require a blood sample.
      By: Wojciech Sobiech
      A PSA blood screening will require a blood sample.
    • The prostate-specific antigen level will increase with an enlarged prostate.
      By: peterjunaidy
      The prostate-specific antigen level will increase with an enlarged prostate.
    • PSA levels are elevated in men who have prostate cancer.
      By: peterjunaidy
      PSA levels are elevated in men who have prostate cancer.
    • PSA helps dissolve the cap of mucus in the cervix and allow sperm to enter the uterus.
      By: reineg
      PSA helps dissolve the cap of mucus in the cervix and allow sperm to enter the uterus.
    • Prostate health may be evaluated via physical examination and ultrasound.
      By: jovannig
      Prostate health may be evaluated via physical examination and ultrasound.
    • Some patients suffering from prostate issues may only feel comfortable seeing a male doctor.
      By: Monkey Business
      Some patients suffering from prostate issues may only feel comfortable seeing a male doctor.
    • Regular prostate exams are essential to maintaining good health after reaching the age of 40.
      By: Tyler Olson
      Regular prostate exams are essential to maintaining good health after reaching the age of 40.