(Prostate Specific Antigen)
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 MontrĂ©al.
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.
- Prostate specific antigen (PSA) facts
- What is prostate specific antigen?
- How is PSA measured?
- What causes PSA elevation in the blood?
- What are normal results for the PSA test?
- What are age-specific reference ranges for serum PSA?
- How is PSA used for early detection prostate cancer?
- What is the free PSA test?
- What is free/total PSA ratio?
- What is PSA velocity and PSA doubling time?
- How is PSA testing used for pretreatment staging of prostate cancer?
- How is PSA testing used in the management of prostate cancer posttreatment?
- What are the limitations of the PSA test?
- What is digital rectal examination (DRE)?
- What is the PSA screening controversy?
- How should the PSA test be used for the early detection of prostate cancer?
- What is PCA3?
Prostate specific antigen (PSA) facts
- The PSA test is a blood test.
- The PSA test can be used to suggest the presence of or monitor prostate cancer.
- The PSA test can be abnormal with benign enlargement and infection of the prostate gland.
- The PSA test can be elevated with other conditions that irritate the prostate gland.
What is prostate specific antigen?
Prostate specific antigen (PSA) is a substance produced almost exclusively by certain cells within the prostate gland. Biochemically, it belongs to the protease family of kallikrein and is also known as human kallikrein 3 (hK3). PSA is secreted by the prostate in the semen where its role is to liquefy the semen following ejaculation. Most of the PSA produced by the prostate gland is carried out of the body in semen, but a very small amount escapes into the blood stream, so PSA is normally found in low amounts (nanograms per milliliter or ng/mL) in the blood.
If the PSA level is high for your age or is steadily increasing (with or without an abnormal physical exam), a biopsy may be recommended. The doctor should consider other risk factors of prostate cancer such as family history and ethnicity before recommending the biopsy. The biopsy is the only way to determine if prostate cancer or other abnormal cells are present in the prostate.
How is PSA measured?
PSA is measured by a blood test. Since the amount of PSA in the blood is very low, detection of it requires a very sensitive type of technology (monoclonal antibody technique). The PSA protein can exist in the blood by itself (known as free PSA), or bound with other substances (known as bound or complexed PSA). Total PSA is the sum of the free and the bound forms. The total PSA is what is measured with the standard PSA test.
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