At a glance

Also known as

total PSA; free PSA; complex PSA

Why get tested?

To help detect and to monitor prostate cancer

When to get tested?

If you have symptoms of prostate disease, such as difficulty in passing urine, or passing urine more frequently than usual and at intervals after treatment for prostate cancer.

There is continued debate among experts and national organisations over when and how often to order the PSA test to screen asymptomatic men. The frequency of prostate cancer screening is an individual decision that should be determined through discussion with your doctor.

Sample required?

A blood sample drawn from a vein in the arm

What is being tested?

Blood is being tested for the level of PSA it contains. PSA is a protein produced mainly by cells in the prostate, a small gland that encircles the urethra in males and produces a fluid that makes up part of semen. Most of the PSA that the prostate produces is released into this fluid, but small amounts of it are also released into the bloodstream. PSA exists in two forms in the blood: free (not bound) and complexed (cPSA, bound to other blood proteins). The most frequently used PSA test is the total PSA, which measures the sum of the free PSA and the cPSA in the blood. When a doctor orders a "PSA test," he is referring to a total PSA.

This test is used as a tumour marker to screen for and to monitor prostate cancer. It is a good tool but not a perfect one, and currently there is no consensus among experts on the usefulness of this test for screening asymptomatic men. Elevated levels of PSA are associated with prostate cancer, but they may also be seen with prostatitis and benign prostatic hyperplasia (BPH). Mild to moderately increased concentrations of PSA may be seen in those of African American heritage, and levels tend to increase in all men as they age.

Recent studies have shown that there is still a small risk of prostate cancer, even if blood PSA levels are normal for age. Therefore even a normal blood PSA level does not mean that there is definitely no prostate cancer present.

The only definite way to confirm whether prostate cancer is present or not is by prostate biopsies (taking small samples of tissue).

 

How is the sample collected for testing?

A blood sample is taken by needle from a vein in the arm. You may be advised to avoid ejaculation and vigorous physical activity affecting the prostate, such as bicycle riding, during the two days before the blood test. The sample should also be collected prior to the physician performing a digital rectal exam (DRE) and prior to (or several weeks after) a prostate biopsy.

The Test

How is it used?

PSA is measured to help detect prostate cancer, and also to monitor the response to treatment in those with prostate cancer. However many elevations of PSA are not due to prostate cancer.

When is it requested?

Using the PSA test to screen healthy men for prostate cancer is somewhat controversial and is not recommended at present in Australia. This is because in many cases PSA testing detects early cancers that are extremely slow-growing and may never cause life-threatening disease - this may cause further unnecessary testing and treatment. However, men who have an increased risk for prostate cancer (such as Afro-Caribbean or African-American men, and those with a family history of the disease) may wish to be screened for prostate cancer.

The total PSA test and DRE may also be ordered when a man has symptoms that could be due to prostate cancer, such as difficult, painful, and/or frequent urination, back pain, and/or pelvic pain. Since these symptoms are seen with a variety of other conditions, including infection and prostatitis, the doctor will also frequently order other tests, such as a urine culture. Some of these conditions can themselves cause temporary increases in PSA levels. If a total PSA level is elevated, a doctor may order a repeat test a few weeks later to determine whether the PSA concentrations have returned to normal.

Free PSA is sometimes requested when total PSA levels are only mildly elevated to try to differentiate between prostate cancer and other non-cancerous conditions such as BPH. It might also be requested in combination with other tests, such as the rectal examination or biopsy, to help confirm a diagnosis of prostate cancer. Once the diagnosis is made, the PSA test might also be used to help your doctor learn about how you are responding to treatment.

What does the test result mean?

The 'normal' value for total PSA are age dependent but total PSA levels greater than 10.0 µg/L may indicate a high probability of prostate cancer. Levels between 4.0 µg/L and 10.0 µg/L may indicate BPH, a non-cancerous swelling of the prostate, or prostate cancer. BPH occurs most frequently in elderly men. Increased total PSA levels may also indicate a condition called prostatitis, which is caused by an infection. It is important to realise that an elevated PSA level does not always indicate the presence of prostate cancer.

There is some evidence that the free PSA ratio (the percent of total PSA not bound to proteins) can help predict the probability of cancer, especially in patients with total PSA levels in the 'grey-area' range of 4.0 to 10.0 µg/L. This test may also be useful in early diagnosis of disease when values are between 2.5 and 4.0 µg/L. A free-PSA test result above 25% is thought to suggest a lower risk of cancer, whereas a lower percentage suggests a higher probability of disease. This ratio may help reduce the number of unnecessary biopsies. A recent study also suggests that very low ratios of free PSA to total PSA (less than 14%) might be associated with a more aggressive form of the disease. Additional studies are ongoing.

In most cases, test results are reported as numbers rather than as 'high' or 'low', 'positive' or 'negative', or 'normal'. In order for the doctor to properly understand laboratory results it is necessary for them to know what the reference range is for a particular test. However, reference ranges can be influenced by the patient's age and sex and, amongst other things, by what drugs they are receiving, the time of day and what they have eaten. Reference ranges can also influenced by the test method and instrument used by laboratory. To learn more about reference ranges see above.

About Reference or “Normal” Ranges

Is there anything else I should know?

Prostate biopsy or operations on the prostate will significantly elevate PSA levels. The blood test should be done before surgery or six weeks after.

Ejaculation and vigorous physical activity affecting the prostate, such as bicycle riding, may cause a temporary rise in PSA levels. It is also thought that a rectal examination prior to PSA testing might temporarily raise PSA levels but recent studies have not shown this to be a consistent finding. Excessive doses of some chemotherapeutic drugs, such as cyclophosphamide and methotrexate, may also increase or decrease PSA levels.

Common Questions

If I have prostate cancer, what are my options?

The most common treatments are discussed elsewhere on this site. For more information visit the sites listed in the Related information section.

Are the recommendations for PSA testing different for different ethnic groups, such as those of Afro-Caribbean descent?

The incidence for disease is greater among Afro-Caribbeans and African-Americans than for Caucasian men. Hence men from these ethnic groups may wish to have their PSA tested earlier than usual.

Will PSA testing detect all prostate cancers?

No. Sometimes cancer cells do not produce much PSA, and the test will be negative when the disease is present.

I have heard my doctor use the terms PSA Density, PSA Velocity, PSA Doubling Time. Please explain what these are.

PSA Density refers to the relationship of the PSA level to the size of the prostate measured by ultrasound examination.

PSA Velocity refers to how quickly PSA levels change over time.

PSA Doubling Time is the time it takes for the PSA value to double. This may be useful in following treatment and determining the type of treatment.


Last Review Date: March 25, 2013