Dr Gonzalo E. Díaz Murillo



Prostate Specific Antigen (PSA )

What is prostate specific antigen?

The first thing to clarify is that having a high PSA does not mean a biopsy is necessary as we will see later on.

A prostate specific antigen or PSA is a protein that is produced in the prostate. Determining its concentration in the blood is an indication of diseases in the male
genitourinary organs.

A large number of diseases in these organs raise the PSA concentration in the blood and cancer of the prostate is only one of these.

The PSA rises with prostatic hypertrophy, urinary and prostatic infections, sexual activity, rectal stimulation such as in transrectal ultrasounds, significant intestinal
constipation or diarrhea, large hemorrhoids, a rectal examination, varicocele, orchitis, etc. As a result, it is not useful on its own in diagnosing prostate cancer or any other prostatic complaint. A high PSA should not be considered to be an indicator of cancer of the prostate much less an indication that a biopsy should be done on the prostate.

PSA. Sirve o no sirve?
PSA works? youtube video

What does a PSA (prostatic specific antigen) exam consist of?

It is the measurement of the PSA concentration in the blood. This test requires a
specific type of preparation and care.


The preparation is simple but should be strictly followed. If not, the results will change.

No food starting 12 hours prior the test

Sexual abstinence for a week before the sample is taken since sexual activity raises the

As of a week prior to the PSA avoid any rectal digital examination and/or transrectal
ultrasound since both of them raise the PSA.

Avoid excessive constipation or diarrhea for a week prior to the exam since they cause
the PSA to rise >

Some medications that are used to treat the prostate typically reduce the concentration
of PSA in the blood. Therefore, it is advisable to stop taking them starting one or two
weeks before the exam.

Precision in the diagnosis of prostate cancer

An elevated PSA does not necessarily mean cancer since the PSA rises for many
reasons other than cancer.

Since the facts listed above have often been ignored, many patients have been
unnecessarily subjected to a biopsy (The National Association of Prostate Cancer
Support Groups).

Furthermore, cancer of the prostate has been detected in men with a PSA
concentration that is lower than 2.0 ng/ml. These cases account for at least 21% of the
total diagnoses of prostate cancer. These data raise doubts about the use of an
arbitrary PSA threshold to select the patients that will be subjected to a biopsy.

We have been advising people not to have biopsies since 2004 even when they have
high PSA levels.

Maximum values of PSA that are considered normal

The tables have varied considerably as new factors that raise or reduce the PSA are
discovered. As mentioned above, it is also common to discover cancer in men whose
PSA is below 2.0 ng/ml. Nor is it rare to find patients with no evidence of cancer of the
prostate but with PSA levels that are above 70 ng/ml. In general, if the level is above 4
ng/ml there is a greater possibility of finding one or more following diseases such as the
ones listed below:

  1. Prostate hypertrophy
  2. Nephritis
  3. Urethritis
  4. Cystitis
  5. Prostatitis
  6. Seminal vesiculitis
  7. An earlier prostate biopsy
  8. Prostate cancer
  9. Orchitis
  10. Varicocele
  11. Extensive hydrocele
  12. Epididymitis
  13. Renal lithiasis
  14. Any surgery in the groin area such as hernia surgery, vasectomy, etc.
  15. Mammary carcinoma
  16. Other changes

Who should have a PSA done

Every man who is over the age of 35 or who has genitourinary symptoms

What is a PSADI

The PSADI (Prostate Specific Antigen Density Index) is the relative prostatic
concentration of the PSA –see C.M.P.– and it is still used as an indicator of the
possibility of prostate cancer although its usefulness is limited in the absence of other
data. The C.M.P., which includes the PSADI, is the best exam for detecting what is
elevating the PSA at present.

Assessment of the treatment for prostate cancer

Since one of the things that causes prostate antigen to rise is cancer (there are many
more), measuring this is basically oriented towards the growth/remission of cancer. If
its concentration in the blood rises, it is assumed that cancer is growing. If it declines, it
is assumed that the cancer is responding to the treatment. Naturally, the person should
follow the instructions given above for the test since otherwise, the results will be

The PSADI velocity is a much more precise test. This is the velocity at which the
PSADI rises or falls over the course of time. The PSADI is part of the C.M.P. –

The U.S. Preventive Services Task Force (USPSTF) recommended eliminating the
PSA test as a way of detecting prostate cancer in October 2011. This was due to the
fact that they found scientific evidence indicating that the benefits of reducing deaths
from cancer are surpassed by the potential side effects derived from treating a cancer
that would have never caused any damage.

This does not mean that the PSA is useless. On the contrary, it is very useful as a first
test that is sensitive but non-specific for determining the presence of diseases of the
masculine urinary ducts in the early stages, and cancer is one of them.

The fact that the PSA seems to be elevated does NOT MEAN THAT THERE IS
CANCER. It only means that there are problemas that require treatment and that one
of these problems could be cancer, which may or may not need treatment.

Furthermore, the PSA test is simple, inexpensive, and only requires a blood sample. It
is sensible to have it done periodically or whenever the doctor advises it to be done.


The PSA rises as a result of genitourinary diseases. Its elevation does not indicate
cancer, let alone a need for a biopsy. It only indicates the presence of genitourinary

The C.M.P. - Prostate detects all of the known causes of an elevated prostate antigen
(PSA). Treating said causes reduces the PSA. Thus, if the PSA has dropped after the
treatment, there is no need for concern.

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