PSA (prostate-specific antigen)
Prostate protein measured in the blood and debated as a screening test
Also known as
Definition
PSA (prostate-specific antigen) is a protein made by both normal and cancerous cells of the prostate; a small amount in the blood is normal. The test is used to screen for prostate cancer, to look into prostate symptoms and to monitor the course after a diagnosis. A raised level does not show where it comes from: besides cancer, an enlarged prostate or inflammation can also raise PSA.
| Parameter | Value |
|---|---|
| Unit | ng/ml (µg/l) |
| Reference Range | There is no single normal value. A total PSA above 4.0 ng/ml is often considered abnormal; some doctors use a lower cut-off for younger men (about 2.5 ng/ml) and a higher one for older men (about 5 ng/ml). Labs and guidelines differ; your report is what counts, and your doctor interprets the result. |
Agree on your personal target range with your doctor.
1 ng/ml equals 1 µg/l. Medicines for an enlarged prostate such as finasteride and dutasteride lower PSA; lower cut-offs are used in that case.
↓ What a low value means
A low PSA level is the normal case. It does not reliably rule out prostate cancer, though: according to MedlinePlus, a low level is possible even when cancer is present. After cancer treatment, the course is judged over several measurements; what a value means then is for your doctor to interpret.
↑ What a high value means
A high PSA level can be related to prostate cancer, but also to an enlarged prostate (BPH), inflammation of the prostate, a urinary tract infection or certain medicines. In general, the higher the level, the more likely cancer is, yet a high level without cancer is common. According to the NCI, about 6 to 7% of men have a false-positive result in any screening round, and cancer is found in only about a quarter of men who have a biopsy because of a raised level. Usual next steps are a repeat test, a digital rectal exam, a urine test or an MRI; only a biopsy can confirm cancer. Discuss the approach with your doctor.
When to test
Whether a screening PSA test is right for you is a personal decision you make with your doctor. Age (risk rises after 50), prostate cancer in the family, general health and how you weigh benefits and harms all play a role. Other reasons are urinary symptoms, blood in urine or semen, and monitoring after a diagnosis. It is common to avoid ejaculation and vigorous exercise such as cycling for 24 to 48 hours before the test.
Frequently asked questions
What are the benefits and harms of PSA screening? +
According to the NCI, screening can find prostate cancer earlier and slightly lowers deaths from prostate cancer over ten years. On the other side are false-positive results, biopsies with possible bleeding and infection, and overdiagnosis: some cancers found grow so slowly that they would never have caused symptoms, but treating them can lead to incontinence or erectile dysfunction.
From what age is PSA screening discussed? +
The US Preventive Services Task Force (USPSTF) advises making an individual decision between ages 55 and 69 and recommends against PSA screening from 70. Some organizations recommend regular testing from 40 or 45 for men at higher risk, for example with prostate cancer in a father or brother. Recommendations differ by country; talk to your doctor about it.
What can raise PSA temporarily? +
According to the NCI and MedlinePlus, ejaculation, vigorous cycling, inflammation or infection of the prostate and a recent biopsy, among others. Inflammation and biopsies can raise the level for one to two months.
What happens after a high result? +
Without symptoms, the test is often repeated after six to eight weeks first. If the level stays high or keeps rising, a digital rectal exam, urine test, MRI or biopsy may follow. Which steps make sense is something you decide together with your doctor.
PSA (prostate-specific antigen)
Sources
Last updated: October 05, 2026
This information is for orientation only and does not replace medical advice. Reference ranges can vary by laboratory, method and country.