PSA

Prostate-specific antigen, or PSA, is a protein produced by normal, as well as malignant, cells of the prostate gland. The PSA test measures the level of PSA in the blood. For this test, a blood sample is sent to a laboratory for analysis. The results are usually reported as nanograms of PSA per milliliter (ng/mL) of blood.

The PSA test is a blood test used primarily to screen for prostate cancer.

The test measures the amount of prostate-specific antigen (PSA) in your blood. PSA is a protein produced by both cancerous and noncancerous tissue in the prostate, a small gland that sits below the bladder in males.

PSA is mostly found in semen, which also is produced in the prostate. Small amounts of PSA ordinarily circulate in the blood.

The PSA test can detect high levels of PSA that may indicate the presence of prostate cancer. However, many other conditions, such as an enlarged or inflamed prostate, also can increase PSA levels. Therefore, determining what a high PSA score means can be complicated.

There is a lot of conflicting advice about PSA testing. To decide whether to have a PSA test, discuss the issue with your doctor, considering your risk factors and weighing your personal preferences.

Why it’s done

Prostate cancer is common, and it is a frequent cause of cancer death. Early detection may be an important tool in getting appropriate and timely treatment.

Prostate cancer can cause elevated levels of PSA. However, many noncancerous conditions also can increase the PSA level. The PSA test can detect high levels of PSA in the blood but doesn’t provide precise diagnostic information about the condition of the prostate.

The PSA test is only one tool used to screen for early signs of prostate cancer. Another common screening test, usually done in addition to a PSA test, is a digital rectal exam.

In this test, your doctor inserts a lubricated, gloved finger into your rectum to reach the prostate. By feeling or pressing on the prostate, the doctor may be able to judge whether it has abnormal lumps or hard areas.

Neither the PSA test nor the digital rectal exam provides enough information for your doctor to diagnose prostate cancer. Abnormal results in these tests may lead your doctor to recommend a prostate biopsy.

During a prostate biopsy, samples of prostate tissue are removed for laboratory examination. A diagnosis of cancer is based on the biopsy results.

Other reasons for PSA tests

For those who have already been diagnosed with prostate cancer, the PSA test may be used to:

• Judge the effectiveness of a treatment
• Check for recurring cancer