PSA
(Prostate Specific Antigen)
 |
PSA is a substance that is produced 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.
A PSA
blood test measures how much prostate tissue is in the body.
It may be evaluated in four conditions: |
- An enlarged prostate obviously has more tissue in it so will
produce more
PSA especially if the prostate is rich in glands. However, a prostate may be
enlarged due to fibrous tissue and not have an elevated 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 recommended that men above 50
years of age get at least a yearly PSA. Men under 50 years of age, if
there is any history of cancer of the prostate in the family or a patient has
had prostate problems in the past, should have a PSA yearly.
