What is prostate specific antigen?

The prostate specific antigen (PSA) is an enzyme that is produced by epithelial cells of the prostate gland and is used to thin the semen of a male. A small amount of PSA is always in the bloodstream, but its elevated levels may indicate an abnormal condition of the gland. The PSA test will allow us to detect if there is a high level of PSA in a patient, as a high level of PSA may indicated the presence of prostate cancer. Having high levels of PSA does not always mean the patient has prostate cancer, as there are many other conditions which may increase PSA levels in an individual such as an enlarged or inflamed prostate.

The PSA test can be used in men who are not known to have the diseases as a screening test. It can normally be used to gauge the aggressiveness of prostate cancer, and it can be used in men with prostate cancer to monitor their disease. However PSA is not specific to prostate cancer as many other diseases can cause an elevated PSA level. The most frequent being the benign prostatic hypertrophy (BPH), which is when the prostate increases in size, this normally happens with aging. Prostatitis which is an infection of the prostate gland is another relatively common cause of an elevated PSA. Other conditions that may contribute to an elevated PSA level are ischemia or infarction, urinary retention, prostate biopsy and urethral instrumentation.

Not all subjects who have prostate cancer produce a good portion of detectable level increase in the blood PSA, even with an advanced diseases, which is one of the limitations of the PSA screening test.


Why measure the levels of prostate specific antigen?

Prostate specific antigen is considered a marker of potential prostate problems, its usefulness however was often questioned because of the limited sensitivity of this enzyme. Elevated levels of PSA may indeed suggest the presence of the benign disorder, due to conditions such as that of a tumor in the prostate.

The most frequent PSA level at its highest is 4ng/mL, however since the prostate gland generally increases in size and produces more PSA with increasing age, it is normal to have lower levels in younger males, and therefore higher levels in older males. There are age specific PSA levels and are as follows, age 40 to 49, 2.5 ng/mL, age 50 to 59, 3.5 ng/mL, age 60 to 69, 4.5 ng/mL, age 70 to 79, 6.5 ng/mL When the levels of PSA increase over 10ng/mL, the probability of prostate cancer increases dramatically. These however are not the best indicators of age related PSA levels as there are many factors that can affect them. It is however better to take 4ng/mL as the highest normal value of PSA in the blood.


Standard of preparation

Sampling is usually done in the morning, when you visit the hospital. The doctor will recommend if you need to be fasting prior to the examination. It is important that you inform your doctor of any medication that you are currently taking as it may affect the results of the examination. It may also be necessary in some cases to include your prior medical history.


Is the exam painful or dangerous?

The examination is neither painful nor dangerous. The patient may feel a slight tingling sensation when the needle enters the arm.


How is the exam performed?

The examination is done by a simple blood test.