PSA Test (Prostate Specific Antigen)

  • Medical Author:
    Kevin C. Zorn, MD, FRCSC, FACS

    Dr. Kevin Zorn is a dual-board-certified (US and Canada), minimally-invasive uro-oncology, fellowship trained urologist at the University of Chicago. His main focus of clinical and scientific interest is in the surgical treatment of renal and prostate cancer. He is also an expert in performing surgery with the DaVinci Surgical Robotic System to manage localized prostate cancer and small renal masses. Dr. Zorn studied medicine and urology at McGill University in Montréal.

  • Medical Author: Pierre-Alain Hueber, MD, PhD
  • Medical Editor: Melissa Conrad Stöppler, MD
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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What causes PSA elevation in the blood?

It is believed that elevation of PSA in the blood is due to its liberation into the circulation because of disruption of the prostate cellular architecture (structure). This can occur in the setting of different prostate diseases including prostate cancer. It is important to note that PSA is not specific to prostate cancer but to prostatic tissue and therefore PSA elevations may indicate the presence of any kind of prostate disease. Common benign causes of PSA elevation includes benign prostatic hyperplasia or BPH (an age-related, natural enlargement of the prostate, secondary to a noncancerous proliferation of prostate glandular cells), prostatitis (inflammation of the prostate), and infection. In fact, PSA elevation can also occur with prostate manipulation such as ejaculation, prostate examination, urinary retention or catheter placement, and prostate biopsy. It is for these reasons that patients should abstain from sex 1 to 2 days prior to PSA testing. As such, men choosing to undergo PSA testing should be aware of these important factors, which may influence results. As will be discussed shortly, age and prostate volume may also influence PSA test results.

What are normal results for the PSA test?

The "normal" PSA serum concentration remains a debate, however, for most laboratory readings, it should be less than 4.0 ng/mL. The prostate gland generally increases in size and produces more PSA with increasing age, so it is normal to have lower levels in young men and higher levels in older men. As such, the concept of age-adjusted PSA normals have been described and recommended. The PSA level also depends on ethnicity and family history of prostate cancer. Other than the single reading, the changes in PSA numbers on an annual basis (also referred to as PSA-velocity) also play a role in decision making about the PSA marker. The normal increase of less than 0.75 ng/mL is used to help determine whether levels may be suggestive of disease and to counsel men on management. As such, a man 50 to 59 years of age with an increase in PSA levels from 0.5 ng/mL to 2.5 ng/mL may have prostate cancer despite the normal value at that time.

Medically Reviewed by a Doctor on 1/14/2016

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