PSA

Answer 1

Definition

PSA stands for prostate-specific antigen. It is a protein found in prostate cells. It can be detected at a low level in the blood of all adult men.

This article discusses the blood test to measure the amount of PSA in a man's blood.

Alternative Names

Prostate-specific antigen; prostate cancer screening test

How the test is performed

Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

How to prepare for the test

No special preparation is usually needed.

How the test will feel

When the needle is inserted to draw blood, some people feel moderate pain while others feel only a prick or stinging sensation. Afterward, there may be some throbbing or a bruise.

Why the test is performed

This test is done to screen for prostate cancer. It is also used to monitor patients after prostate cancer treatment.

Several conditions besides cancer can cause the PSA level to rise, including:

• Benign prostatic hyperplasia
• Prostatitis
• Recent catheterization or cystoscopy
• Urinary tract infections

Discuss with your doctor or health care provider whether a PSA test is appropriate for you.

Normal Values

Normal values vary with age. Older men typically have slightly higher PSA measurements than younger men. Men with a larger prostate will also have higher PSA values.

Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

What abnormal results mean

A high PSA level has been linked to an increased chance of having prostate cancer. However, a high PSA level does not mean that you definitely have prostate cancer. A high PSA level only identifies patients at higher risk of having prostate cancer. People at higher risk may need to have more tests.

A PSA of 4 nanograms per milliliter (ng/mL) is abnormally high for most men and may indicate the need for a prostate biopsy. For men under age 50, levels above 2 ng/mL may be too high. A significant rise from one year to the next may also indicate a higher risk of having prostate cancer.

Keep in mind that although PSA testing is an important tool for detecting prostate cancer, it is not foolproof.

Greater-than-normal PSA levels may indicate:

• Benign prostatic hypertrophy
• Prostate cancer
• Prostate infection (prostatitis)
• Urinary tract infection

What the risks are

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

Special considerations

Discuss the benefits and risks of testing with your doctor to determine whether screening is right for you.

• Potential benefits include early diagnosis of cancer
• Potential risks include increased health care costs, unnecessary invasive testing (biopsy) and treatment

The American Urologic Association, American Cancer Society, and National Comprehensive Cancer Network recommend that:

• All men ages 40 - 75 have annual PSA tests
• Screening should also include a prostate examination by your doctor

However, these guidelines are not recommended for everyone. Many health organizations, including the US Preventive Services Task Force, do not recommend routine PSA testing.

References

American Urological Association. Prostate-specific antigen best practice statement: 2009 update. April 2009. Accessed July 10, 2009.

Lin K, Lipsitz R, Miller T, Janakiraman S. U.S. Preventive Services Task Force. Benefits and harms of prostate-specific antigen screening for prostate cancer: an evidence update for the U.S. Preventive Services Task Force. Ann Intern Med. 2008;149:192-199.

Lim LS, Sherin K; ACPM Prevention Practice Committee. Screening for prostate cancer in U.S. men ACPM position statement on preventive practice. Am J Prev Med. 2008;34:164-170.

Walsh PC, DeWeese TL, Eisenberger MA. Clinical practice. Localized prostate cancer. N Engl J Med. 2007;357:2696-2705.

Walter LC, Bertenthal D, Lindquist K, Konety BR. PSA screening among elderly men with limited life expectancies. JAMA. 2006;296:2336-2342.

Answer 2

Definition

PSA stands for prostate-specific antigen. It is a protein produced by prostate cells.

This article discusses the blood test to measure the amount of PSA in a man's blood. The PSA test is done to help diagnose and follow prostate cancer in men.

Alternative Names

Prostate-specific antigen; Prostate cancer screening test

How the test is performed

A blood sample is needed. For information on how this is done, see: Venipuncture

How to prepare for the test

Make sure your doctor knows all the medications you are taking. Some drugs may cause your PSA levels to be falsely low. These include finasteride, dutasteride, saw palmetto use, and antiandrogen drugs, such as flutamide, nilutamide, and bicalutamide.

No other special preparation is usually needed.

How the test will feel

When the needle is inserted to draw blood, some people feel moderate pain while others feel only a prick or stinging sensation. Afterward, there may be some throbbing or a bruise.

Why the test is performed

Reasons for a PSA test:

• This test may be done to screen for prostate cancer.
• It is also used to follow patients after prostate cancer treatment to see if the cancer has come back.
• If a healthcare provider feels the prostate gland is not normal during physical exam

For information about prostate cancer screening, see the "Considerations" section below.

Normal Values

PSA test results cannot diagnose prostate cancer. Only a prostate biopsy can diagnose this cancer.

Your doctor will look at your PSA results and must consider your age, your race, medicines you are taking, and many other things to decide whether your PSA is normal and whether you need more tests done.

Older men typically have slightly higher PSA levels than younger men. Commonly used ranges are as follows:

• Men below age 50: PSA less than 2.5
• Men 50 - 59 years: PSA level less than 3.5
• Men 60 - 69 years: PSA level less than 4.5
• Men older than 70 years: PSA level less than 6.5

The examples above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results.

What abnormal results mean

A high PSA level has been linked to an increased chance of having prostate cancer.

In general, the following results need further follow-up and testing:

• A PSA of 4 nanograms per milliliter (ng/mL) for most men
• For men under age 49, levels above 2.5 ng/mL
• For men aged 50 - 59, levels above 3.5 ng/mL
• For men aged 60 - 69, levels above 4.5 ng/mL
• A significant rise from one year to the next may also indicate a higher risk of having prostate cancer.
• African Americans and Asian Americans may need follow-up testing if they have lower PSA levels.
• A rapidly changing PSA, even within the normal range, raises the likelihood of cancer.

PSA testing is an important tool for detecting prostate cancer, but it is not foolproof. Other conditions can cause a rise in PSA, including

• A larger prostate
• Prostate infection (prostatitis)
• urinary tract infection
• Recent tests on your bladder (cystoscopy) or prostate (biopsy)
• Catheter tube recently placed into your bladder to drain urine

Your doctor will think about the following things when deciding on the next step:

• Your age
• If you had a PSA test in the past and how much and how fast your PSA levels have changed
• If your doctor finds a prostate lump during your exam
• Other symptoms you may have
• Other risk factors for prostate cancer, such as race and family history

People at higher risk may need to have more tests. Your doctor may recommend:

• Repeating your PSA test, most often sometime within 3 months
• A prostate biopsy
• A follow-up test called a free PSA (fPSA). The lower the level of this test, the more likely it is that prostate cancer is present.

For someone who has been treated for prostate cancer, the PSA level can show if a treatment is working or if the cancer has come back. Often, PSA levels will begin to rise before there are any symptoms, sometimes months or years beforehand.

What the risks are

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

Special considerations

Measuring PSA levels can increase the chance of finding prostate cancer when it is very early.

However, the value of PSA screening for prostate cancer is controversial. There is not a single answer that fits all men. Before having the test, it is best to discuss both the reasons to have and the reasons not to have a PSA test with your doctor.

Some questions you may ask your doctor when discussing having a PSA test include:

• What does an abnormal PSA test mean? Does it mean you have cancer?
• If the PSA test is abnormal, what other tests will be needed? Will you need a biopsy?
• What are your risk factors for prostate cancer? Does that change whether you should have a PSA test? What is the best age to start having a PSA test?
• What are the benefits and risks of finding prostate cancer when it is very early?

If a man chooses to be tested, the PSA is most often done every year to screen:

• Men ages 40 - 75
• Men with a family history of prostate cancer (especially a brother or father) and African-American men, who should think about starting around age 40 - 45. This is because they have a higher chance of developing prostate cancer.

PSA testing is not recommended for screening men over age 75.

There are different recommendations about screening tests for prostate cancer. For more information, check with:

• American Urological Association
• National Comprehensive Cancer Network
• American Cancer Society
• The US Preventive Services Task Force (do not recommend routine PSA testing).

References

American Urological Association. Prostate-specific antigen best practice statement: 2009 update. April 2009. Accessed July 10, 2009.

Lin K, Lipsitz R, Miller T, Janakiraman S; U.S. Preventive Services Task Force. Benefits and harms of prostate-specific antigen screening for prostate cancer: an evidence update for the U.S. Preventive Services Task Force. Ann Intern Med. 2008;149:192-199.

Lim LS, Sherin K; ACPM Prevention Practice Committee. Screening for prostate cancer in U.S. men ACPM position statement on preventive practice. Am J Prev Med. 2008;34:164-170.

Walsh PC, DeWeese TL, Eisenberger MA. Clinical practice. Localized prostate cancer. N Engl J Med. 2007;357:2696-2705.

Walter LC, Bertenthal D, Lindquist K, Konety BR. PSA screening among elderly men with limited life expectancies. JAMA. 2006;296:2336-2342.

Wolf AM, Wender RC, Etzioni RB, Thompson IM, D'Amico AV, Volk RJ, et al. American Cancer Society guideline for the early detection of prostate cancer: update 2010. CA Cancer J Clin.2010;60:70-98.

Reviewed By

Review Date: 09/19/2011

David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.; Louis S. Liou, MD, PhD, Chief of Urology, Cambridge Health Alliance, Visiting Assistant Professor of Surgery, Harvard Medical School.