PSA
(Prostate Specific Antigen)
 |
PSA is a substance that is put out by special gland cells in the
prostate. This chemical is very specific to the prostate in
humans and
there is no other tissue in the body that produces PSA. PSA determinations
are very reliable so day after day and from lab to lab the variations are minimal.
However the lower limits of normal can be variable. A PSA
blood test measures how much prostate tissue is in the body.
It may be evaluated in four conditions: |
- An enlarged prostate has more tissue in it so will
produce more
PSA.
- Prostatitis is inflammation in the prostate. This may elevate the
PSA. However, after the prostatitis subsides the PSA usually returns to
normal.
- Infarction in the prostate is where part of the prostate may
be severely damaged because of an inflammation or lack of blood supply.
This
may drive the PSA up. Infarctions are very rare and are very hard to diagnose.
- Cancer of the prostate may cause the PSA
to go up. The more
cancer there is in the body the higher the PSA. The normal value of PSA is
0 - 4. Anything between 4 and 10 may be suspicious of cancer and will require
the patient to have an ultrasound and biopsies. The higher the PSA is above 10 the more chance of cancer in the prostate.
Sometimes the cancer may spread outside the prostate and the PSA will go even
higher, reaching PSA values in the thousands of units. It is our recommendation that men above 40 should have a PSA done yearly. Especially if there is any history of cancer of the prostate.
