Prostate-specific antigen (PSA) is a protein produced by cells of the prostate gland. It is normal for men to have a low level of PSA in their blood. However, prostate cancer or benign (non-cancerous) conditions can increase the PSA level.
The levels of PSA are measured by a blood test. Your doctor takes a blood sample, and the amount of PSA is measured in the laboratory. Because PSA is produced by the body and can be used to detect disease, it is sometimes called a biological marker or a tumour marker. However, a man’s PSA level alone does not give doctors enough information to distinguish between benign prostate conditions and cancer. The doctor will use the results of the PSA test to decide whether to check further for signs of prostate cancer.
The PSA test results show the level of PSA present in blood. The results are usually reported as nanograms of PSA per millilitre of blood or ng/mL. In the past, doctors considered a PSA level below 4.0 ng/mL as normal. However, studies have shown that prostate cancer can sometimes be present in men with a PSA level at or below 4.0. Also, a PSA level above 4.0 does not mean you have cancer. There can be different reasons for an elevated PSA level besides prostate cancer, including benign prostate enlargement, inflammation, infection, age, and race.
Although 0-4.0 is usually considered normal, there is no specific normal or abnormal PSA level. Consequently, one abnormal PSA test result does not necessarily indicate the need for a prostate biopsy.
In general, the higher a man’s PSA level, the more likely it is that cancer is present. Furthermore, if a man’s PSA level continues to rise over time, other tests may be indicated.
PSA level alone does not give doctor enough information to distinguish between benign prostate conditions and cancer. However, your doctor will take the result of the PSA test into account when deciding whether to check further for signs of prostate cancer.
The PSA test is a simple blood test, so there is no special preparation for this procedure.
The doctor takes a blood sample from your arm. This sample is then exposed to the antibody that attacks PSA, and the amount of PSA is measured.
Some of the limitations of a PSA test include:
The U.S. Food and Drug Administration (FDA) has approved the use of the PSA test along with a digital rectal exam (DRE) to help detect prostate cancer in men 50 years of age or older. During a DRE, a doctor inserts a gloved finger into the rectum and feels the prostate gland through the rectal wall for bumps or abnormal areas. Doctors often use the PSA test and DRE together as prostate cancer screening tests, as they can help detect prostate cancer in men who have no symptoms of the disease.