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Before |
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After |
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Before |
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After |
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Before |
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After |
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Multiple Kidney Stones |
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Stones Removed Endoscopically |
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Multiple Left Kidney
and Ureteric Stones |
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ARTICLE SECTIONS |
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Definition |
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Symptoms |
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Causes |
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Risk factors |
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Tests and diagnosis |
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Complications |
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Treatments and drugs |
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Prevention |
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Definition |
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Kidney stones (renal
lithiasis) are small, hard deposits of
mineral and acid salts on the inner
surfaces of your kidneys. Normally, the
substances that make up kidney stones
are diluted in the urine. When urine is
concentrated, though, minerals may
crystallize, stick together and
solidify. The result is a kidney stone.
Most kidney stones contain calcium.
Passing kidney stones can be
excruciating. The pain they cause
typically starts in your side or back,
just below your ribs, and radiates to
your lower abdomen and groin.
Painful as they are, kidney stones
usually cause no permanent damage.
Medical intervention — apart from pain
medication — is often unnecessary.
Still, it's important to find out
what type of kidney stone you have
and why it developed. Some of the
underlying causes of kidney stones
can be treated to prevent new stones
from forming. If no specific
treatment exists, you may be able to
stave off additional kidney stones
simply by drinking more water and
making a few dietary changes.
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Symptoms |
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Until a kidney stone
moves into the ureter — the tube
connecting the kidney and bladder — you
may not know you have it. At that point,
these signs and symptoms may occur: |
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Pain in the side
and back, below the ribs |
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Fluctuations in pain
intensity, with periods of pain
lasting 20 to 60 minutes |
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Pain waves radiating from
the side and back to the lower
abdomen and groin |
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Bloody, cloudy or
foul-smelling urine |
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Pain on urination |
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Nausea and vomiting |
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Persistent urge to urinate |
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Fever and chills if an
infection is present |
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| Kidney stones that don't cause these
symptoms may show up on X-rays when you
seek medical care for other problems,
such as blood in your urine or recurring
urinary tract infections |
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Causes |
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Kidney
stones |
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Your kidneys are two bean-shaped
organs, each about the size of your
fist. They're located in back of
your abdomen on each side of your
spine, and their main function is to
remove excess fluid, unneeded
electrolytes and wastes from your
blood in the form of urine. The
ureters carry urine from your
kidneys to your bladder, where it's
stored until you eliminate it from
your body.
Kidney stones form when the
components of urine — fluid and
various minerals and acids — are out
of balance. When this happens, your
urine contains more crystal-forming
substances, such as calcium and uric
acid, than the available fluid can
dilute. At the same time, your urine
may be short of substances that keep
crystals from sticking together and
becoming stones. Kidney stones are
also prone to develop in highly
acidic or highly alkaline urine.
Problems in the way your system
absorbs and eliminates calcium and
other substances create the
conditions for kidney stones to
form. Sometimes, the underlying
cause is an inherited metabolic
disorder or kidney disease. Gout
promotes specific types of kidney
stones, as does inflammatory bowel
disease. So do some drugs, including
furosemide (Lasix), used in treating
heart failure and high blood
pressure; topiramate (Topamax), an
anti-seizure drug; and indinavir
(Crixivan), which is used to treat
human immunodeficiency virus, the
cause of AIDS.
It's common, however, for kidney
stones to have no definite, single
cause. A number of factors, often in
combination, create the conditions
in which susceptible people develop
kidney stones. Most kidney stones
contain crystals of more than one
type. Determining the type that
makes up the bulk of the stone —
usually a combination of calcium
compounds — helps identify the
underlying cause. The best
preventive approach after your first
kidney stone also depends partly on
the stone's composition.
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Calcium stones. Roughly four
out of five kidney stones
are calcium stones, usually
in the form of calcium
oxalate. Oxalate is found in
some fruits and vegetables,
but the liver produces most
of the body's oxalate
supply. Dietary factors,
high doses of vitamin D,
intestinal bypass surgery
and several different
metabolic disorders can
increase the concentration
of calcium or oxalate in
urine.
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Struvite stones. Found more
often in women, struvite
stones are almost always the
result of urinary tract
infections. Struvite stones
may be large enough to fill
most of a kidney's
urine-collecting space,
forming a characteristic
stag's-horn shape.
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Uric acid stones. These
stones are formed of uric
acid, a byproduct of protein
metabolism. You're more
likely to develop uric acid
stones if you eat a
high-protein diet. Gout also
leads to uric acid stones.
Certain genetic factors and
disorders of the
blood-producing tissues also
may predispose you to the
condition.
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Risk factors |
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These factors may
increase your risk of developing kidney
stones: |
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Lack of fluids. If you don't
drink enough fluids,
especially water, your urine
is likely to have higher
concentrations of substances
that can form stones. That's
also why you're more likely
to form kidney stones if you
live in a hot, dry climate
or exercise strenuously
without replacing lost
fluids.
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Family or personal history.
If someone in your family
has kidney stones, you're
more likely to develop
stones too. And if you've
already had one or more
kidney stones, you're at
increased risk of developing
another.
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Age and sex. Most people who
develop kidney stones are
between 20 and 70 years of
age. Men are more likely to
develop kidney stones than
are women.
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Diet. A high-protein,
high-sodium and low-calcium diet
may increase your risk of some
types of kidney stones. |
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Limited activity. You're
more prone to develop kidney
stones if you're bedridden
or very sedentary for a long
period of time. That's
partly because limited
activity can cause your
bones to release more
calcium.
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Obesity. High body mass
index (BMI), increased waist
size and weight gain have
been linked to kidney stones
in long-term studies of
large populations. The
relationship is strongest in
women.
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High blood pressure. Having
high blood pressure doubles your
risk of forming kidney stones. |
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Gastric bypass surgery,
inflammatory bowel disease
or chronic diarrhea. Changes
in the digestive process
affect your absorption of
calcium and increase the
levels of stone-forming
substances in your urine.
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Tests And Diagnosis |
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Many kidney stones go
unnoticed until they cause acute
symptoms — specifically, the pain of a
stone going through your ureter.
Sometimes, however, kidney stones are
discovered in the course of looking for
the cause of chronic urinary tract
infections or blood in the urine.
If your doctor suspects you have kidney
stones, you're likely to have a blood
analysis to look for excess calcium or
uric acid and a 24-hour collection of
urine to check whether you're excreting
too many stone-forming minerals or too
few inhibiting substances.
You may also have one or more of the
following imaging tests: |
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Computerized tomography (CT)
scan. This imaging test has
become the standard of care
for evaluating acute kidney
stones. It's rapidly
performed, can identify
stones regardless of
composition and doesn't
require the use of contrast
dye.
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Abdominal X-ray. An
abdominal X-ray can
visualize most kidney stones
and can help to judge
changes in the size of a
stone over time.
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Ultrasound. Instead of
X-rays, this diagnostic
technique combines
high-frequency radio waves
and computer processing to
view your internal organs.
It's safe, painless and
noninvasive, but it may miss
small stones, especially if
they're located in a ureter
or your bladder.
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Intravenous pyelography
(excretory urogram). This
study can be useful in
determining the location of
stones in the urinary system
and can define the degree of
blockage caused by a stone.
A contrast dye is injected
into a vein in your arm and
a series of X-rays is taken
as the dye moves through
your kidneys, ureters and
bladder. This study has
largely been replaced by the
CT scan but is still useful
in limited circumstances
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Complications |
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If a stone stays
inside one of your kidneys, it usually
doesn't cause a problem unless it
becomes so large it blocks the flow of
urine. This can cause pressure and pain,
along with the risk of kidney damage,
bleeding and infection. Smaller stones
may partially block the thin tubes that
connect each kidney to your bladder or
the outlet from the bladder itself.
These stones may cause ongoing urinary
tract infections or kidney damage if
left untreated. |
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Treatments And Drugs |
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Treatment for kidney
stones varies, depending on the type of
stone and the cause. You may be able to
move a stone through your urinary tract
simply by drinking plenty of water — as
much as 2 to 3 quarts (1.9 to 2.8
liters) a day — and by staying
physically active.
Stones that can't be treated with
more-conservative measures — either
because they're too large to pass on
their own or because they cause
bleeding, kidney damage or ongoing
urinary tract infections — may need
professional treatment. Procedures
include:
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Extracorporeal shock wave
lithotripsy (ESWL). This is
a commonly used procedure
for treating kidney stones.
It uses shock waves to break
the stones into tiny pieces
that are then passed in your
urine. In some cases, you
may be partially submerged
in a tub of water during the
procedure. In others, you
may lie on a soft cushion.
You'll generally require
sedation or light anesthesia
due to moderate pain caused
by the shock waves. A loud
noise is produced each time
a shock wave is generated,
and you'll wear earphones to
protect your hearing.
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Your doctor will likely use
X-rays or ultrasound to help
determine the position of
the stone as well as to
monitor the status of the
stone during treatment.
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Complications that may occur
with ESWL include blood in
the urine, bruising on the
back or abdomen, bleeding
around the kidney and other
adjacent organs, and
discomfort as the stone
fragments pass through the
urinary tract. In addition,
if the stone doesn't shatter
completely, you may need a
second round of ESWL or
ureteroscopic stone removal.
After treatment, it may take
months for all the stone
fragments to pass.
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Percutaneous
nephrolithotomy. When ESWL
isn't effective, or the
stone is very large, your
surgeon may remove your
kidney stone through a small
incision in your back using
an instrument called a
nephroscope.
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Ureteroscopic stone removal.
This procedure may be used
to remove a stone lodged in
a ureter. The stone is
snared with a small
instrument (ureteroscope)
that's passed into the
ureter through your bladder.
Ultrasound or laser energy
also can be directed through
the scope to shatter the
stone. These methods work
especially well on stones in
the lower part of the
ureter.
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Parathyroid surgery. Some
calcium stones are caused by
overactive parathyroid
glands, which are located on
the four corners of your
thyroid gland, just below
your Adam's apple. When
these glands produce too
much parathyroid hormone,
your body's level of calcium
can become too high,
resulting in excessive
excretion of calcium in your
urine. Most often, this is
the result of a small benign
tumor in one of your four
parathyroid glands. A doctor
can surgically remove the
tumor.
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Prevention |
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In many cases, you
can prevent kidney stones by making a
few lifestyle changes. If these measures
aren't effective and blood and urine
tests reveal a correctable chemical
imbalance or that the stones you have
are getting bigger, your doctor may
prescribe certain medications.
Lifestyle changes
For people with a history of kidney
stones, doctors usually recommend
passing at least 2.5 quarts (2.3 liters)
of urine a day. To do this, you'll need
to drink about 14 cups (3.3 liters) of
fluids every day — and even more if you
live in a hot, dry climate.
What should you drink? Water is best.
Include a glass of lemonade every day,
too. Make your own with real lemons, or
use a liquid or frozen concentrate, but
avoid powdered lemonade mixes. Lemonade
increases the levels of citrate in your
urine, and citrate helps prevent stone
formation.
In addition, if you tend to form calcium
oxalate stones, your doctor may
recommend restricting foods rich in
oxalates. These include rhubarb, star
fruit, beets, beet greens, collards,
okra, refried beans, spinach, Swiss
chard, sweet potatoes, sesame seeds,
almonds and soy products. What's more,
studies show that an overall diet low in
salt and very low in animal protein can
greatly reduce your chance of developing
kidney stones.
As a general rule, restricting your
intake of calcium doesn't seem to lower
your risk. In fact, researchers have
found that women with a high calcium
intake are less likely to develop kidney
stones than are women who consume less
calcium. Why? Dietary calcium binds with
oxalates in the gastrointestinal tract
so that oxalates can't be absorbed from
the intestine and excreted by the kidney
to form stones.
An exception to this rule occurs when an
individual absorbs too much dietary
calcium from the intestine. In such a
circumstance, restricting calcium intake
is useful.
Calcium supplements seem to have the
same protective effect as dietary
calcium, but only if they're taken with
meals.
Medications
Medications can control the level of
acidity or alkalinity in your urine and
may be helpful in people who form
certain kinds of stones. The type of
medication your doctor prescribes will
depend on the kind of kidney stones you
have: |
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Calcium stones. To help
prevent calcium stones from
forming, your doctor may
prescribe a thiazide
diuretic or a
phosphate-containing
preparation. If you have
calcium stones because of a
condition known as renal
tubular acidosis, your
doctor may suggest taking
sodium bicarbonate or
potassium bicarbonate.
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Uric acid stones. Your
doctor may prescribe
allopurinol (Zyloprim,
Aloprim) to reduce uric acid
levels in your blood and
urine and a medicine to keep
your urine alkaline. In some
cases, allopurinol and an
alkalinizing agent may
dissolve the uric acid
stones.
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Struvite stones. To prevent
struvite stones, the first
goal is to keep urine free
of bacteria that cause
infection. Long-term use of
antibiotics in small doses
may be useful to achieve
this goal.
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