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Prostate-Specific Antigen (PSA) Test
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Lab Tests

Prostate-Specific Antigen (PSA) Test

A PSA test is a blood test used to screen for prostate cancer and monitor prostate conditions by measuring the level of a specific protein produced by the prostate gland.

What is a prostate-specific antigen (PSA) test?

A prostate-specific antigen (PSA) test is a blood test that measures the level of PSA in a sample of your blood. PSA is a protein made by your prostate, a gland in the male reproductive system located just below the bladder that makes the fluid part of semen.

It is normal to have a low level of PSA in your blood. A high PSA level may be caused by:

  • Prostate cancer
  • An enlarged prostate (also called benign prostatic hyperplasia or BPH)
  • Prostatitis, which is inflammation (swelling and pain) in the prostate gland
  • Other common prostate problems
  • Urinary tract infections (UTIs)
  • Taking certain medicines

A PSA test cannot show what is causing abnormal levels; if your level is high, you may need other tests. Other names for this test include total PSA and free PSA.

What is it used for?

A PSA test is used to screen for prostate cancer. Screening looks for signs of cancer before symptoms appear, but it cannot diagnose cancer. If signs are found, further testing is required to determine if cancer is present and how serious it may be.

Because many prostate cancers grow slowly and may never cause health problems, the goal of screening is to identify cancers more likely to spread. However, there are challenges and potential harms:

  • Inability to distinguish causes: A PSA test cannot differentiate between abnormal levels caused by cancer versus noncancerous conditions. A prostate biopsy is the only way to confirm cancer, and it carries risks such as bleeding, infection, or difficulty urinating.
  • Overdiagnosis and overtreatment: Screening may lead to the treatment of cancers that would never have affected your health. Treatment can cause serious side effects, including erectile dysfunction, urinary incontinence, and bowel incontinence.

When deciding if screening is right for you, discuss your risk for serious prostate cancer, your general health, and your personal preferences with your health care provider. PSA testing is also used to help diagnose noncancerous prostate conditions and to monitor treatment for prostate conditions, including cancer.

Why do I need a PSA test?

Deciding to have a PSA test is a personal choice. Your risk for serious prostate cancer may be higher based on:

  • Age: Risk increases after age 50.
  • Family health history: A family history of prostate cancer may increase your risk.
  • Race: Prostate cancer is more common in Black men, who also have a higher risk of developing the disease at a younger age and having more serious disease.

You may also need a PSA test if you have symptoms of a prostate condition, such as:

  • Painful, slow, or frequent urination
  • Blood in urine or semen
  • Pelvic or back pain
  • Urinary incontinence

What happens during a PSA test?

A health care professional will collect a blood sample from a vein in your arm using a small needle. The process usually takes less than five minutes.

Will I need to do anything to prepare for the test?

You must avoid sex or masturbation for 24 hours before the test, as releasing semen can increase PSA levels and affect accuracy. Inform your provider about any medicines you take, but do not stop taking them unless instructed.

Are there any risks to the test?

There is very little risk. You may experience slight pain or bruising at the needle site, but symptoms typically resolve quickly.

What do the results mean?

There is no specific normal or abnormal level. Generally, higher levels increase the likelihood of cancer, but it is possible to have a high PSA without cancer or a low PSA with cancer.

If you had a test for screening or symptoms, high levels may indicate cancer or a noncancerous condition. Your provider may suggest:

  • Follow-up PSA testing: To see if levels change over time.
  • Digital rectal exam (DRE): A provider uses a gloved, lubricated finger to feel the prostate for abnormalities.
  • Urine test: To check for infection.
  • Prostate biopsy: A minor surgery to remove tissue samples for microscopic study, which is the only way to diagnose cancer.

If you are being monitored for existing prostate cancer, your provider will evaluate multiple test results over time to understand your condition.

Frequently Asked Questions

Most guidelines suggest discussing PSA screening with a doctor starting at age 50 for average‑risk men. Men with a family history of prostate cancer, African‑American men, or those with other risk factors may begin conversations at age 40–45. If you choose to screen, repeat testing is typically done every 1–2 years, depending on the initial level and any changes over time.
PSA of 6 ng/mL is above the commonly used “normal” threshold of 4 ng/mL, indicating an increased likelihood of prostate pathology, but it does not diagnose cancer. Causes can include benign prostatic hyperplasia, prostatitis, recent urinary tract infection, or recent ejaculation. Your doctor will likely repeat the test, assess PSA velocity (change over time), and may order a free‑to‑total PSA ratio or imaging before recommending a biopsy.
Yes. Certain medications (5‑alpha‑reductase inhibitors like finasteride) can lower PSA by about 50 %, so labs often adjust the reported value. Ejaculation within 48 hours can raise PSA modestly (≈0.1–0.2 ng/mL). Acute prostatitis or a urinary tract infection can cause a transient spike, sometimes doubling the baseline. It’s best to avoid ejaculation for 48 hours and treat any infection before drawing blood for PSA.
negative biopsy does not guarantee the absence of cancer, especially if PSA stays high or rises. Options include: repeat biopsy (often with MRI‑targeted sampling), monitor PSA trends more closely (every 3–6 months), consider a free‑to‑total PSA ratio or PSA density, and evaluate for non‑cancerous causes (BPH, prostatitis). Discuss with your urologist whether a watchful‑waiting approach or further imaging is appropriate.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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