PSA (Prostate-Specific Antigen)
Also written as: Prostate-specific antigen, Total PSA
A protein made by the prostate, used in prostate health checks and cancer screening discussions.
What it measures
The level of prostate-specific antigen, a protein made by prostate gland cells and released into the blood in small amounts. All prostate tissue makes PSA, so the test reflects prostate activity of any kind, not one specific condition.
Why a doctor orders it
Ordered to help evaluate prostate symptoms, to follow known prostate conditions, and as a screening test for prostate cancer. PSA screening is an individualized decision made together with a clinician, since expert bodies differ on when and whether to screen.
What is generally associated with a higher result
Broadly associated with prostate cancer, but equally with common benign prostate enlargement, prostate inflammation or infection, urinary tract infection, and recent physical disturbance of the gland - including ejaculation, cycling, or a recent prostate exam. Values also drift upward gradually with age.
What is generally associated with a lower result
Low values are generally reassuring and not pursued. Some prostate-shrinking medications lower PSA substantially, which is factored in when the result is read.
Everyday things that move this number
Not every shift in a value reflects disease. These are ordinary factors known to affect this particular measurement:
- Ejaculation in the days before the draw
- Recent cycling or other pressure on the perineum
- A recent prostate exam or urinary catheter
- Urinary tract infection or prostate inflammation
- Medications that shrink the prostate, which lower PSA
Questions to take to your appointment
- Could recent activity, such as cycling or ejaculation, have raised this?
- Do I take any medication that lowers PSA and changes how it should be read?
- What are the potential benefits and downsides of PSA screening in my situation?
- Is the free-to-total PSA ratio something worth checking?
Build a printable questionnaire with your own results →
Where to read more
MedlinePlus, from the US National Library of Medicine, publishes patient-facing pages on individual lab tests and is a reliable next stop: medlineplus.gov/lab-tests .
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