Last updated: October 2026.
Quick answer: a PSA test is a blood test that measures prostate-specific antigen, a protein made by the prostate, in ng/mL. A higher level can be a sign of prostate cancer, but an enlarged prostate, infection, recent ejaculation and age also raise it. No single number proves cancer is present or absent. Men 55 to 69 should decide with their doctor whether to be screened.
The PSA test is the most common way men over 50 are screened for prostate cancer. It is simple, cheap and widely available. It is also easy to misread, because PSA rises for many reasons that have nothing to do with cancer.
This guide explains what the result means, PSA levels by age, what can cause high PSA and what happens after an abnormal result. For the wider picture, see our prostate health after 50 guide.
PSA test at a glance
| Question | Short answer |
|---|---|
| What it measures | Prostate-specific antigen in the blood, in ng/mL |
| How it is done | A standard blood draw from the arm |
| Traditional cut-off | 4.0 ng/mL, though many doctors now judge PSA by age, prostate size and trend |
| Can it diagnose cancer? | No. Only a biopsy can confirm prostate cancer |
| Who should consider screening | Men 55 to 69, after talking with a doctor; higher-risk men often earlier |
| Main benefit | Can find prostate cancer early |
| Main harms | False positives, biopsy complications and overdiagnosis |
What is a PSA test?
A PSA test measures how much prostate-specific antigen is in your blood. PSA is a protein made by cells in the prostate, the small gland below the bladder. Most of it goes into semen, but a small amount enters the bloodstream.
The result is reported in nanograms per milliliter (ng/mL). Prostate cancer can raise PSA, but so can several harmless conditions. That is why a high result is a reason for more checks, not a diagnosis.
What is a normal PSA level?
There is no single normal PSA level, and no level guarantees that cancer is present or absent. For years, 4.0 ng/mL was the usual cut-off for more testing. Some men with cancer have PSA below that, and many men above it do not have cancer.
Today many doctors read PSA in context. They look at your age, the size of your prostate and how the number changes over time. A steady rise across several tests often matters more than one reading.
PSA levels by age
PSA levels by age rise naturally, because the prostate tends to grow as men get older. The ranges below are commonly cited upper limits. Labs and doctors use different ranges, so ask yours how they interpret your result.
| Age | Commonly cited upper limit |
|---|---|
| 40 to 49 | Up to 2.5 ng/mL |
| 50 to 59 | Up to 3.5 ng/mL |
| 60 to 69 | Up to 4.5 ng/mL |
| 70 to 79 | Up to 6.5 ng/mL |
What causes high PSA besides cancer?
The most common cause of high PSA is not cancer but an enlarged prostate, also called benign prostatic hyperplasia (BPH). Several other things can raise the number for a short time.
| Cause | Why it raises PSA | What usually helps |
|---|---|---|
| Enlarged prostate (BPH) | A larger gland makes more PSA | Doctor may use PSA density to adjust for size |
| Prostatitis or urinary tract infection | Inflammation releases more PSA into the blood | Treat the infection, then repeat the test |
| Recent ejaculation | Can raise PSA briefly | Avoid for about 48 hours before the test |
| Vigorous cycling | Pressure on the prostate area | Avoid for a day or two before the test |
| Catheter or prostate procedure | Irritates the gland | Wait as your doctor advises before testing |
| Older age | PSA tends to rise with age | Compare with age-based ranges |
Learn more in what causes enlarged prostate symptoms and our guide to prostatitis symptoms, types and treatment.
Who should get a PSA test and when?
The US Preventive Services Task Force (USPSTF) says men 55 to 69 should make an individual decision with their doctor about PSA screening. It recommends against routine PSA screening for men 70 and older.
Some men are at higher risk and often start the conversation earlier. Many experts suggest starting around age 40 to 45 for:
- Black men
- Men whose father or brother had prostate cancer
If you choose screening, your doctor will suggest how often to repeat the PSA test based on your result and risk.
Benefits and harms of PSA screening
A screening PSA test can find prostate cancer early, but it also carries real harms. That trade-off is why guidelines call it a personal decision.
- Benefit: it can find cancer before it causes symptoms, when treatment options are wider.
- False positives: a high result often turns out not to be cancer, which can cause worry and more tests.
- Biopsy complications: a biopsy can cause bleeding, pain or infection.
- Overdiagnosis: screening can find slow-growing cancers that would never have caused harm, and treating them can cause side effects.
How should you prepare for a PSA test?
A few simple steps help make sure the PSA test reflects your usual level.
- Avoid ejaculation for about 48 hours before the test.
- Avoid vigorous cycling for a day or two before.
- Tell your doctor about every medicine and supplement you take.
- Test when you do not have a urinary infection.
What happens if your PSA is high?
A high result on a PSA test usually leads to a repeat test and further checks, not straight to a biopsy. The usual next steps are:
- Repeat the PSA test to see whether the level stays high.
- Check for infection and treat it before retesting.
- Free PSA percentage: a lower share of free PSA can point to a higher chance of cancer.
- PSA density: compares PSA with prostate size.
- MRI: many men now have a prostate MRI before any biopsy.
- Biopsy if needed: the only way to confirm cancer.
If a biopsy finds low-risk cancer, many men choose active surveillance, which means regular monitoring instead of immediate treatment. Our prostate cancer vs BPH guide explains how the two are told apart.
Can supplements or medicines change your PSA?
Some prescription medicines lower PSA, while common prostate supplements do not appear to change it in a meaningful way.
Finasteride and dutasteride, used to treat an enlarged prostate, lower the PSA test result by about half after several months. Doctors adjust the reading to account for this, so always tell them you take one. Treatment choices are covered in BPH treatment options.
Large trials found that saw palmetto does not meaningfully change PSA. We review that evidence in does saw palmetto lower PSA. Do not use any supplement to try to change your PSA test result.
If you are looking at supplements for urinary symptoms, see our review of the best prostate supplements, and tell your doctor before your next test.
When should you see a doctor?
See a doctor about any abnormal PSA result, and promptly if you have symptoms. Red flags include:
- Blood in the urine or semen
- Pain or burning when urinating, or fever with urinary symptoms
- Being unable to urinate
- A weak stream or urgency that is new or getting worse
- Waking often at night to urinate (see frequent urination at night)
- New pain in the back, hips or pelvis that does not go away
- A PSA that keeps rising across repeat tests
PSA test FAQ
What is a normal PSA test result?
There is no single normal result. 4.0 ng/mL was the traditional cut-off for more testing, but many doctors now judge PSA by your age, prostate size and how the number changes over time.
What are normal PSA levels by age?
Commonly cited upper limits are 2.5 ng/mL for ages 40 to 49, 3.5 for 50 to 59, 4.5 for 60 to 69 and 6.5 for 70 to 79. Labs and doctors use different ranges.
Does high PSA mean I have cancer?
No. High PSA is often caused by an enlarged prostate, prostatitis, a urinary infection, recent ejaculation or older age. Further tests such as a repeat PSA, MRI and sometimes a biopsy are needed.
At what age should I get a PSA test?
The USPSTF says men 55 to 69 should decide with their doctor. Many experts suggest Black men and men with a father or brother who had prostate cancer start the conversation around 40 to 45.
Should men over 70 have PSA screening?
The USPSTF recommends against routine PSA screening for men 70 and older, because the harms are likely to outweigh the benefits. Men with symptoms should still see their doctor.
How do I prepare for a PSA test?
Avoid ejaculation for about 48 hours and vigorous cycling for a day or two before the blood draw. Tell your doctor about medicines and supplements, and do not test during a urinary infection.
Can medicines lower my PSA?
Yes. Finasteride and dutasteride lower PSA by about half after several months. Doctors adjust the reading for this, so always tell them if you take either medicine.
Does saw palmetto lower PSA?
Large trials found that saw palmetto does not meaningfully change PSA. It should not be used to try to change a test result, and you should tell your doctor if you take it.
What happens after a high PSA result?
Your doctor will usually repeat the test, check for infection and may order free PSA, PSA density or an MRI. A biopsy is done only if these suggest it is needed.
Bottom line
A PSA test is a useful but imperfect screening tool. It can find prostate cancer early, but high PSA has many harmless causes, and no number is a diagnosis. Read your result against your age, prostate size and trend, prepare properly, and make the screening decision with your doctor.
References
- US Preventive Services Task Force: Prostate Cancer Screening
- National Cancer Institute: Prostate Cancer
- American Cancer Society: Prostate Cancer
- MedlinePlus: Prostate-Specific Antigen (PSA) Test
- American Urological Association: Guidelines
This article is for information only and is not medical advice. Talk with your doctor about whether prostate cancer screening is right for you.