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McKesson Clinical Reference Systems: Women's Health Advisor 2002.2
Illustration
Illustration
Kidney Stones
What are kidney stones?
Kidney stones are gravel-like collections of chemicals that
may appear in any area of the urinary system, from the
kidney to the bladder. They may be small or large, single
or multiple.
How does this occur?
Of the four main types of urinary stones, calcium stones are
the most common. Almost 95% of all kidney stones are
calcium stones. They occur when there is too much calcium
in the urine. Defective kidney function may allow too much
calcium in the urine, or excessive calcium may be absorbed
from the stomach and intestines. Some calcium stones are
caused by an excess of a chemical called oxalate, present in
many foods, which binds easily with calcium to form a stone.
The risk of calcium stone formation is increased if you have
certain medical diseases; for example, hyperparathyroidism
and inflammatory bowel disease.
A second type of kidney stone is made of uric acid. These
stones are much less common than calcium stones. Uric acid
stones occur because you have too much uric acid in your
urine. They might occur if you have become dehydrated; for
example, during strenuous exercise on a hot day or perhaps
during an illness. Uric acid stones are common in people
who have gout, a disease that causes high uric acid levels
in the blood.
A third type, struvite stones, are not quite so well
understood. It is thought that these stones form as a
result of an interaction between protein-breakdown products
and infection-causing bacteria in the urine.
Finally, a rare type of kidney stone is a cystine stone. It
occurs if you have the genetic disease called cystinuria.
This disease results from a birth defect that causes the
kidney to allow too much cystine into the urine. This type
of stone formation is almost always diagnosed during
childhood.
What are the symptoms?
The most common symptom of kidney stones is severe back or
abdominal pain. This may be accompanied by nausea and
vomiting. If you have a urinary tract infection as well,
your symptoms may include fever, chills, sweats, and pain
with urination.
Kidney stones and urinary tract infection can cause blood
to be in the urine. Usually the blood is seen only with a
microscope, but occasionally it is more obvious.
Some people have no kidney stone symptoms until they pass
gravel-like stones in their urine. Others never have any
symptoms, and their stones are found incidentally during
testing for other problems.
How is it diagnosed?
Your doctor may suspect you have kidney stones if you have
severe abdominal or back pain with no other likely causes.
He or she will look for blood in your urine.
Sometimes the pattern of pain over time is helpful in the
diagnosis. The pain may move from the upper to the lower
abdomen over a few hours. As the stone moves lower, the
pain may be felt in the genitals, especially the labia.
You may have one or more of the following tests:
- CT scan (computerized x-rays)
- x-ray
- ultrasound scan
- intravenous pyelogram (IVP), which is a special type of
x-ray done after a dye is injected into one of your
veins.
How is it treated?
Kidney stone treatment depends on the size and location of
the stone(s), whether one or more stones are blocking the
flow of urine out of the kidney, and whether there is
evidence of infection.
You may be treated at home by drinking lots of liquids and
taking pain medication. Kidney stones usually pass on their
own. Your doctor will ask you to strain all urine until the
stone is passed. This allows the stone to be identified
with lab tests.
If you are vomiting too much to drink liquids, you may need
to be hospitalized. A stay in the hospital may also be
necessary if you have signs of urinary infection, a kidney
abnormality, or a large stone requiring surgery.
If you have a stone in the lower urinary tract that
requires surgery, it may be removed, under anesthesia,
through a cystoscope. This instrument is a slim, lighted,
flexible, fiber-optic telescope, which is passed through the
urethral opening into the urinary tract. Tiny tools can be
passed through the cystoscope and used to trap and remove
the stone.
A stone that is too high or too large may require open
abdominal surgery for removal. However, a new method for
removal is being used in some centers: Higher or larger
stones are removed through a type of operating telescope (a
ureteroscope). The ureteroscope is inserted via the
bladder.
At a few medical centers, ultrasound machines are available
to destroy stones with shock waves (a technique called
lithotripsy).
How long will the symptoms last?
The phase of acute, intermittent pain usually lasts hours to
1 to 2 days. A stone, however, may take days or even weeks
to pass. Sometimes weekly x-rays will be necessary to track
the progress of the stone down the urinary tract. If the
stone has not passed after a month or so, it may need to be
surgically removed.
How can I take care of myself?
- Follow your doctor's instructions.
- Make sure you drink enough liquids.
- Watch for signs of kidney infection, such as fever,
chills, sweats, and worsening back or abdominal pain.
- Get help, if you need it, with the straining of your
urine.
- Take the pain medicine prescribed by your doctor.
- Make sure you tell your doctor if any difficulties or
questions arise.
What can be done to help prevent kidney stones?
If you do not have any underlying health problems, the most
important thing is to drink plenty of water daily. The goal
should be to urinate from 2 to 4 liters per day. Make sure
you avoid getting dehydrated.
There are no specific dietary recommendations until a stone
from your system has been analyzed. After analysis your
diet can be evaluated and any changes recommended.
Because kidney stones are associated with a number of
metabolic diseases, it is important to be under the care of
a physician for the stones. Any underlying causes can then
be identified and treated. In this way complications
besides kidney stones can be prevented.
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