Written by Dr.Albana Greca Sejdini, Md, MMedSc

Prostate Specific Antigen Blood Test: What and why?

What is the prostate specific antigen blood test?

If you are complaining from prostate problems, you doctor will probably advise you to perform the PSA test. Normally, the cells of your prostate gland produce a protein substance called prostate-specific antigen (PSA).

PSA blood test detects the levels of this protein (PSA) in your blood. Moreover, PSA is known to be a tumor marker, because prostate tumor cells release an increased amount of PSA in your blood, therefore high levels of PSA blood test usually indicate the presence of certain types of prostate cancer.

Why is prostate specific antigen blood test performed?

Your doctor will recommend you to have a PSA test :

    • every year if your age is 50 years or older

    • if you are at high risk of having prostate cancer, i.e. if you are African American or have positive family history for prostate cancers, then your doctor will probably advise you to start screening PSA levels at the age of 40 or 45.

The U.S. Food and Drug Administration (FDA)

 has advised doctors to use both PSA test and digital rectal exam (DRE) to spot prostate cancer for men at the age of fifty years and older. Your doctor will use PSA test and DRE as screening tests to detect the presence of prostate cancer, even if you don’t have any symptoms of the disease.

Moreover, if you have a history of prostate cancer, and your doctor suspect that cancer has recurred, FDA has revealed that high PSA level in your blood can be the early sign of recurrence.

How to read the results of a Prostate Specific Antigen Blood Test?

The amount of PSA is expressed in nano-grams per one milliliter of your blood; therefore, the results of PSA test are reported in ng/ml unit. In the past, doctors have considered your PSA test results of 4 ng/ml or less as normal. But recent clinical studies have reported that fifteen percent of men diagnosed with prostate cancer had reported PSA levels of below or at 4 ng/ml.

Therefore, experts consider that there are no abnormal or normal levels of PSA. In fact, non-cancerous prostate conditions, like benign prostate hyperplasia or prostatitis can raise your PSA levels. Furthermore, if you are already receiving hormone therapy for prostate cancer, then your PSA levels are more likely to be low.

How to perform a Prostate Specific Antigen Blood Test?

To perform PSA test; your doctor will draw a blood sample, mainly from your arm, and send it to the laboratory. The results usually appear in few days. Recently, there are new techniques available for PSA tests, which will help your doctor to decide whether you will need a biopsy or not, including:

    • PSA velocity: It involves the measurement of the change in the levels of PSA over time. You are more likely to have prostate cancer if your PSA velocity is > 0.75 ng/ml per year.

    • PSA density: This correlate the size of your prostate and PSA levels in your blood.

    • Free versus attached PSA: Normally, PSA circulates in two forms in your blood: free or attached to a molecule of protein. Fortunately, this test can determine exactly what sort of prostate condition you might have.

    For example, if you suffer from benign prostate problem (e.g. BPH), then you may have anincreased free PSA. While if you have any type of prostate cancers, your attached PSA will raise.

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