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The
Prostate Gland
The
prostate is a walnut-sized gland that forms part of the male
reproductive system. The gland is made of two lobes, or regions,
enclosed by an outer layer of tissue. The prostate is located in
front of the rectum and just below the bladder, where urine is
stored. The prostate also surrounds the urethra, the canal
through which urine passes out of the body.
Scientists
do not know all the prostate's functions. One of its main roles,
though, is to squeeze fluid into the urethra as sperm move
through during sexual climax. This fluid, which helps make up
semen, energizes the sperm and makes the vaginal canal less
acidic.
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Why
BPH Occurs
The
cause of BPH is not well understood. For centuries, it has been
known that BPH occurs mainly in older men and that it doesn't
develop in men whose testes were removed before puberty. For
this reason, some researchers believe that factors related to
aging and the testes may spur the development of BPH.
Throughout
their lives, men produce both testosterone, an important male
hormone, and small amounts of estrogen, a female hormone. As men
age, the amount of active testosterone in the blood decreases,
leaving a higher proportion of estrogen. Studies done with
animals have suggested that BPH may occur because the higher
amount of estrogen within the gland increases the activity of
substances that promote cell growth.
Another
theory focuses on dihydrotestosterone (DHT), a substance derived
from testosterone in the prostate, which may help control its
growth. Most animals lose their ability to produce DHT as they
age. However, some research has indicated that even with a drop
in the blood's testosterone level, older men continue to produce
and accumulate high levels of DHT in the prostate. This
accumulation of DHT may encourage the growth of cells.
Scientists have also noted that men who do not produce DHT do
not develop BPH.
Some
researchers suggest that BPH may develop as a result of
"instructions" given to cells early in life. According
to this theory, BPH occurs because cells in one section of the
gland follow these instructions and "reawaken" later
in life. These "reawakened" cells then deliver signals
to other cells in the gland, instructing them to grow or making
them more sensitive to hormones that influence growth.
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BPH
Symptoms
Many
symptoms of BPH stem from obstruction of the urethra and gradual
loss of bladder function, which results in incomplete emptying
of the bladder. The symptoms of BPH vary, but the most common
ones involve changes or problems with urination, such as
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a
hesitant, interrupted, weak stream
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urgency
and leaking or dribbling
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more
frequent urination, especially at night
The
size of the prostate does not always determine how severe the
obstruction or the symptoms will be. Some men with greatly
enlarged glands have little obstruction and few symptoms while
others, whose glands are less enlarged, have more blockage and
greater problems.
Sometimes
a man may not know he has any obstruction until he suddenly
finds himself unable to urinate at all. This condition, called
acute urinary retention, may be triggered by taking
over-the-counter cold or allergy medicines. Such medicines
contain a decongestant drug, known as a sympathomimetic. A
potential side effect of this drug may be to prevent the bladder
opening from relaxing and allowing urine to empty. When partial
obstruction is present, urinary retention also can be brought on
by alcohol, cold temperatures, or a long period of immobility.
It
is important to tell your doctor about urinary problems such as
those described above. In 8 out of 10 cases, these symptoms
suggest BPH, but they also can signal other, more serious
conditions that require prompt treatment. These conditions,
including prostate cancer, can be ruled out only by a doctor's
exam.
Severe
BPH can cause serious problems over time. Urine retention and
strain on the bladder can lead to urinary tract infections,
bladder or kidney damage, bladder stones, and incontinence. If
the bladder is permanently damaged, treatment for BPH may be
ineffective. When BPH is found in its earlier stages, there is a
lower risk of developing such complications.
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Diagnosis
of BPH
You
may first notice symptoms of BPH yourself, or your doctor may
find that your prostate is enlarged during a routine checkup.
When BPH is suspected, you may be referred to a urologist, a
doctor who specializes in problems of the urinary tract and the
male reproductive system. Several tests help the doctor identify
the problem and decide whether surgery is needed. The tests vary
from patient to patient, but the following are the most common.
Digital
Rectal Exam (DRE)
This
exam is usually the first test done. The doctor inserts a gloved
finger into the rectum and feels the part of the prostate next
to the rectum. This exam gives the doctor a general idea of the
size and condition of the gland.
Prostate
Specific Antigen (PSA) Blood Test
In
order to rule out cancer as a cause of urinary symptoms, your
doctor may recommend a PSA blood test. PSA, a protein produced
by prostate cells, is frequently present at elevated levels in
the blood of men who have prostate cancer. The U.S. Food and
Drug Administration has approved a PSA test for use in
conjunction with a digital rectal exam to help detect prostate
cancer in men age 50 or older and for monitoring prostate cancer
patients after treatment. However, much remains unknown about
the interpretation of PSA levels, the test's ability to
discriminate cancer from benign prostate conditions, and the
best course of action following a finding of elevated PSA.
Because
many unanswered questions surround the issue of PSA screening,
the relative magnitude of its potential risks and benefits is
unknown. Both PSA and ultrasound tests enhance detection when
added to DRE screening. But they are known to have relatively
high false-positive rates, and they may identify a greater
number of medically insignificant tumors. Thus, PSA screening
might lead to treatment of unproven benefit that could result in
morbidity (including impotence and incontinence) and mortality.
It cannot be determined from earlier studies whether PSA
screening will reduce prostate cancer mortality. Ongoing studies
are addressing this issue.
Rectal
Ultrasound
If
there is a suspicion of prostate cancer, your doctor may
recommend a test with rectal ultrasound. In this procedure, a
probe inserted in the rectum directs sound waves at the
prostate. The echo patterns of the sound waves form an image of
the prostate gland on a display screen.
Urine
Flow Study
Sometimes
the doctor will ask a patient to urinate into a special device
that measures how quickly the urine is flowing. A reduced flow
often suggests BPH.
Intravenous
Pyelogram (IVP)
IVP
is an x ray of the urinary tract. In this test, a dye is
injected into a vein, and the x ray is taken. The dye makes the
urine visible on the x ray and shows any obstruction or blockage
in the urinary tract.
Cystoscopy
In
this exam, the doctor inserts a small tube through the opening
of the urethra in the penis. This procedure is done after a
solution numbs the inside of the penis so all sensation is lost.
The tube, called a cystoscope, contains a lens and a light
system, which help the doctor see the inside of the urethra and
the bladder. This test allows the doctor to determine the size
of the gland and identify the location and degree of the
obstruction.
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BPH
and Prostate Cancer: No Apparent Relation
Although
some of the signs of BPH and prostate cancer are the same,
having BPH does not seem to increase the chances of getting
prostate cancer. Nevertheless, a man who has BPH may have
undetected prostate cancer at the same time or may develop
prostate cancer in the future. For this reason, the National
Cancer Institute and the American Cancer Society recommend that
all men over 40 have a rectal exam once a year to screen for
prostate cancer.
After
BPH surgery, the tissue removed is routinely checked for hidden
cancer cells. In about 1 out of 10 cases, some cancer tissue is
found, but often it is limited to a few cells of a nonaggressive
type of cancer, and no treatment is needed.