What does it measure?
PSA is a protein made by prostate tissue. This test measures its total amount in blood, including protein-bound and free forms. It can be used in a discussion about early detection or to monitor someone with a known prostate condition.
Before the test
- Sample
- A blood sample from a vein.
- Before collection
- Ask about recent ejaculation, cycling, infection, and prostate procedures; these can affect timing.
- Medicines
- Tell the clinician if you use finasteride or dutasteride; they can lower PSA. Do not change prescribed treatment for the test unless your clinician advises it.
What can the result mean?
A higher PSA can occur with prostate cancer, but also with benign enlargement or inflammation. A lower value does not rule cancer out. The result is a starting point for assessment, not a cancer diagnosis or an automatic instruction to have a biopsy. [1]
When is it useful, and how is it read?
Separate early-detection discussions from follow-up after a known diagnosis or treatment. Age, family history, symptoms, examination, previous PSA values, and medicines shape the interpretation. The same number can mean different things in these different settings. [1]
What can affect it?
Age, prostate size, infection, recent ejaculation or prostate procedures, and certain medicines affect interpretation. Testing for people without symptoms should follow a shared discussion of possible benefits, false alarms, and overdiagnosis. [1]
Myth: «A raised PSA is a cancer diagnosis»
Prostate enlargement and inflammation can also raise PSA. Its job is to inform an assessment; a single high value cannot confirm cancer or decide the next step on its own. [1]
Questions you might have
Does a high PSA confirm cancer?
No. Benign enlargement and inflammation can raise PSA too. [1]
Is PSA screening right for everyone?
No. The decision weighs age, individual risk, possible benefit, and harms such as unnecessary biopsies. [1]
What comes next?
If PSA is unexpectedly raised, your clinician may repeat it under suitable conditions and consider your history, examination, or further assessment. Bring previous results so that comparisons use the same context. [1]
Given my age, family history, and preferences, how would this test change my care?
The reference interval and units on your report are part of understanding your result. Understand units, reference intervals, and treatment targets.
Sources & references
Medical references & original research
Books we consulted
References that informed our explanations of the test and its context.
- Pagana KD, Pagana TJ, Pagana TN. Mosby’s Diagnostic and Laboratory Test Reference. 14th ed. Elsevier; 2019.
Practical-section sources accessed: .
For general health education. Interpreting your result and deciding on tests or treatment requires your health context and a qualified clinician.
