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. The prostate is a gland in the male reproductive system. It lies just below the bladder. It makes the fluid part of semen.

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

• Prostate cancer
• An enlarged prostate (BPH) (benign prostatic hyperplasia)
• Other common prostate problems
• Taking certain medicines

A PSA test can't show what is causing abnormal PSA levels. So, if your level is high, you may need other tests.

Other names: total PSA free PSA

What is it used for?

A PSA test is used to screen for prostate cancer. Cancer screening means looking for signs of cancer before it causes symptoms. But screening tests can't diagnose cancer. If a screening test finds signs of cancer, you'll need other tests to find out if you have cancer and how serious it may be.

Most types of prostate cancer grow very slowly. They don't spread beyond the prostate and may never cause health problems. In fact, you can live a long life with prostate cancer and never know you have it. The goal of prostate cancer screening is to help find cancers that may be more likely to spread so they can be treated early. But there are challenges and possible harms from using a PSA test to screen for prostate cancer:

• A PSA test can't tell the different between abnormal PSA levels from prostate cancer and noncancerous conditions. If your PSA level is high, a prostate biopsy is the only way to find out if the cause is cancer. And prostate biopsies have possible harms.
• A PSA test may lead to finding and treating prostate cancer that would never have affected your health. If prostate cancer is found:
  • It can be difficult to tell the difference between slow-growing cancers and those that are likely to grow faster and spread in your body.
  • You could have prostate cancer treatment that you never really needed. And cancer treatment may cause serious harms, such as:
    • Erectile dysfunction
    • Urinary incontinence
    • Problems controlling your bowels (poop)

To decide whether a PSA test to screen for prostate cancer is right for you, talk with your health care provider about:

• Your risk for developing a serious type of prostate cancer. If your risk is high, the possible benefits of finding cancer early may outweigh the possible harms.
• Your general health. Are you well enough to have treatment for prostate cancer if it's found?
• Your preferences. How do you feel about the possible benefits and harms of screening, diagnosis, and treatment?

PSA testing may also be used to:

• Help diagnose the cause of prostate conditions that aren't cancer
• Monitor treatment for a prostate condition, including cancer

Why do I need a PSA test?

It's your choice whether to have a PSA test to screen for cancer. You and your prover may consider your risk for developing a serious cancer that could spread if you don't catch it early. Your risk for serious prostate cancer may be higher depending on your:

• Age. The risk of prostate cancer increases after age 50.
• Your family health history. If members of your family have had prostate cancer, your risk may be higher.
• Your race. Prostate cancer is more common in African Americans. They also have a higher risk of developing prostate cancer at a younger age and having more serious disease.

You may also have a PSA test if:

• You have symptoms of a prostate condition, such as:
  • Painful or frequent urination (peeing)
  • Blood in urine or semen
  • Pelvic and/or back pain
• You have prostate cancer. Your provider may use PSA testing to monitor your condition or to see how well treatment is working.

What happens during a PSA test?

A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

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

You will need to avoid having sex or masturbating for 24 hours before your PSA test. That's because releasing semen can increase your PSA levels, which may make your results less accurate. Also, certain medicines may affect your test results, so tell your provider about any medicines you take.

Are there any risks to the test?

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

What do the results mean?

There is no specific normal or abnormal level for PSA in blood. In general, the higher your PSA level, the more likely it is that you have cancer. But it's possible to have a high PSA without prostate cancer, or a low PSA with prostate cancer.

If you had a PSA test for a prostate cancer screening or because you have prostate symptoms:

• High PSA levels can mean you have prostate cancer or a prostate condition that's not cancer, such as an infection (prostatitis) or an enlarged prostate. If your PSA levels are higher than normal, your provider may talk with you about having more tests to diagnose the cause. These tests may include:
  • Another PSA test, more commonly if you don't have any symptoms. PSA levels can go up and down, so it helpful to see if your PSA levels change over time.
  • A digital rectal exam (DRE). For this test, your provider inserts a gloved, lubricated finger into your rectum to feel your prostate for lumps or anything unusual.
  • A urine test. A sample of your urine is tested for infection.
  • A prostate biopsy. A biopsy is minor surgery. A doctor removes samples of tissue from your prostate so it can be studied under a microscope to look for cancer cells. A biopsy is the only way to diagnose cancer. It may be recommended if your provider thinks you may have prostate cancer.

If you had a PSA test to monitor prostate cancer or treatment, ask your provider what a high PSA level means. Your provider will usually look at several tests results over time to get a fuller understanding of your condition.

If you have questions about your results, talk with your provider.

Learn more about laboratory tests, reference ranges, and understanding results.