What is a PSA test? The prostate blood test explained
The PSA test is a simple blood test, but deciding whether to have one is not always simple. This guide explains what the test measures, what a raised result can and cannot mean, and why official bodies ask people to weigh the benefits and harms with a doctor first.
What PSA is
PSA stands for prostate-specific antigen. The US National Cancer Institute (NCI) explains that it is a protein made by both normal and cancerous cells of the prostate gland, and that the PSA test measures its level in the blood. Prostate cancer can raise PSA, but so can several conditions that are not cancer - especially an enlarged prostate (benign prostatic hyperplasia, BPH) and inflammation of the prostate (prostatitis) (NCI: Prostate-Specific Antigen (PSA) Test).
The NHS describes the prostate as a small, walnut-sized gland under the bladder that makes a fluid which mixes with sperm to form semen, and the PSA test as a blood test that helps check for prostate conditions such as prostate cancer or an enlarged prostate (NHS: PSA test).
What the test is used for
NCI lists three main uses:
- Checking symptoms - such as painful or frequent urination, blood in urine or semen, or pelvic or back pain.
- Screening - testing people without symptoms to look for prostate cancer.
- Monitoring - following people already diagnosed with or treated for prostate cancer. A rising PSA after treatment can be the first sign that cancer has come back, although NCI notes a single raised result does not always mean that.
The NHS lists symptoms that may lead a doctor to suggest a PSA test, including peeing more often, a sudden urge to pee or getting up often at night to pee, blood in your pee, and problems getting or keeping an erection. These symptoms have many possible causes, which is why they need a doctor's assessment. See also our list of warning signs to see a doctor about.
Is PSA screening recommended?
This is where the PSA test differs from many other screening tests. NCI states that the PSA test is not recommended for routine prostate cancer screening in the general population, and that most organisations now advise people considering it to discuss the risks and benefits with their doctor first.
- United States: the US Preventive Services Task Force (USPSTF) says that for men aged 55 to 69, the decision to have PSA-based screening should be an individual one, made after discussing the potential benefits and harms with a clinician. It recommends against PSA-based screening for men aged 70 and older (USPSTF: Prostate Cancer Screening, 2018). The USPSTF website shows that an update is in progress.
- England: the NHS says routine PSA testing is not currently offered, except for people whose genetic tests show a change in the BRCA2 gene. Anyone with a prostate can ask a GP about the test, and the GP will discuss the benefits and risks before a decision is made.
- Higher risk: NCI notes that some organisations recommend routine testing from age 40 or 45 for people at higher risk, including Black men, men with inherited BRCA2 (and to a lesser extent BRCA1) variants, and men whose father or brother had prostate cancer. If this applies to you, raise it with your doctor and see is cancer hereditary?
Possible benefits and harms
NCI explains that the possible benefit of PSA screening is finding prostate cancer earlier, when it may be easier to treat, and that a review of randomised trials found a small reduction in deaths from prostate cancer over 10 years. Against this, NCI and the USPSTF list important harms:
- False positives - a raised PSA when there is no cancer. NCI reports that about 6% to 7% of men have a false-positive result in any screening round, and that only about 25% of men who have a biopsy because of a raised PSA are found to have prostate cancer.
- Biopsy side effects - NCI lists possible infection, pain and bleeding.
- Overdiagnosis and overtreatment - some prostate cancers grow so slowly they would never cause problems, but treating them can cause urinary, bowel and sexual side effects.
- Not every early cancer is curable - NCI notes that some tumours may already have spread before they are found.
These trade-offs are why the decision is personal. Our guide to cancer screening explained describes false positives and overdiagnosis in more detail.
How to prepare
Some everyday things can raise PSA for a short time. The NHS advises that for 48 hours before a PSA test you should not ejaculate, have anal sex, do anything that leaves you out of breath (such as exercise), or ride a bike. You can eat and drink as usual. If you have a urine infection, the NHS says you will need to wait 4 to 6 weeks after it has cleared before having the test. NCI adds that prostate infection or inflammation, or a recent prostate biopsy, can raise PSA for a month or two.
Tell the doctor about all medicines you take. NCI notes that some drugs used for an enlarged prostate, such as finasteride and dutasteride, lower PSA levels, which changes how a result is read. Do not stop or change any medicine without medical advice.
What happens during the test
The test is a standard blood sample, usually taken at a GP surgery or hospital. The NHS says you may also be offered a urine test and a rectal examination, in which a health professional feels the prostate with a gloved finger. If needles worry you, tell the person taking the blood. The NHS says results usually come back in 1 to 2 weeks.
What is a "normal" PSA level?
NCI explains that there is no single level that separates normal from abnormal, partly because no specific PSA level means a person has prostate cancer. In general, the higher the PSA, the more likely cancer is present. NCI notes that a level above 4.0 ng/mL has commonly been treated as abnormal, but that PSA rises with age and some doctors use different cut-offs for older and younger men. This is why the number on its own is not a diagnosis, and why your doctor will interpret it with your age, history and other tests.
If your PSA is raised
The NHS stresses that a high PSA does not mean you have cancer. Common next steps described by NCI and the NHS include:
- Repeating the test - NCI says a doctor may repeat it in 6 to 8 weeks to confirm the result.
- Watching over time - repeat PSA tests and examinations to look for change.
- Imaging - such as an MRI scan of the prostate.
- Biopsy - small samples of prostate tissue taken with a needle and examined under a microscope. This is the test that confirms whether cancer is present.
Our guide to how cancer is diagnosed explains imaging and biopsy in general, and our questions to ask your doctor can help you prepare for the conversation.
Sources
- National Cancer Institute: Prostate-Specific Antigen (PSA) Test
- US Preventive Services Task Force: Prostate Cancer Screening (2018; update in progress)
- NHS: PSA test
Published and last reviewed: 21 October 2026.
Common questions
Is a PSA test a blood test?
Yes. The PSA test measures the level of prostate-specific antigen in a blood sample. The NHS says a urine test and a rectal examination are sometimes done at the same visit.
Does a high PSA mean I have cancer?
No. The NHS says a high PSA does not mean you have cancer. NCI explains that an enlarged prostate, prostatitis, infection and other factors can also raise PSA. Further tests are needed to find the cause.
What can affect a PSA test result?
NCI and the NHS list prostate infection or inflammation, a recent biopsy, a urine infection, ejaculation, vigorous exercise and cycling. Some prostate medicines lower PSA. Tell your doctor about these before the test.
At what age should men get a PSA test?
There is no single answer. The USPSTF says screening for men aged 55 to 69 is an individual decision and recommends against it from 70. The NHS does not offer routine testing. Discuss it with your doctor.