Urology
Urological Conditions
Kidney Stones
Kidney Stones–Causes, Risk Factors and Prevention
For unknown reasons, the number of people in the United States
with kidney stones has been increasing over the past 20 years.
Each type of kidney stone has its own set of causes, described
below:
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Calcium stones
One cause of calcium stones is a disorder
called absorptive hypercalciuria. It causes the body to absorb
too much calcium from food. The extra calcium can be emptied
into the urine, causing crystals of calcium oxalate or calcium
phosphate to form in the kidneys or urinary tract. Another
condition that can cause high levels of calcium is hyperparathyroidism,
or overactive parathyroid glands. The parathyroid glands
regulate
calcium. A third cause is a rare metabolic disorder called
hyperoxaluria that makes the body produce too much oxalate,
a salt. When there
is more oxalate than can be dissolved in the urine, the crystals
settle out and form calcium oxalate stones.
-
Struvite (infection) stones
This type of stone
is caused by urinary tract infections and is usually found
more
often in women. For more information about urinary tract
infections, click here. [Note: could put link to urinary tract
infections
page here]
-
Uric acid stones
Uric acid is a by-product of protein
metabolism. Therefore an overabundance of certain foods,
such as meat, in one’s diet may cause excess amounts
of uric acid in the urine. Certain chemotherapy drugs can
also cause
high levels of uric acid in the blood and urine.
-
Cystine stones
Cystinuria is a rare, inherited metabolic
disorder that causes too much of the amino acid cystine
to be excreted into the urine. Because cystine does not dissolve
in
urine, cystinuria can lead to the forming of cystine stones.
Other risk factors include:
-
Certain diseases
Besides the conditions mentioned above,
some common disorders such as gout, chronic urinary
tract infections, cystic kidney disease, as well as rare, inherited
diseases, such
as renal tubular acidosis, can increase the risk
of kidney
stones. Calcium oxalate stones may also form in people who
have a chronic
bowel inflammation or who have had an intestinal
bypass operation, or ostomy surgery.
-
Certain drug treatments
Certain diuretics (water pills)
or calcium-based antacids may increase the risk of forming
kidney stones by increasing the amount of calcium in the
urine. People
who take the protease inhibitor indinavir, a drug
used to treat HIV infection and AIDS, are at risk of developing
kidney
stones.
-
Age
Kidney stones strike most typically between the ages
of 20 and 40.
-
Race
Asians have the lowest rates of the disease. White
Americans are more prone to develop kidney stones than African
Americans.
-
Gender
Stones occur more frequently in men.
-
Family history
A person with a family history of kidney
stones may be more likely to develop stones.
-
Personal history
A person who has already had a kidney
stone may be more likely to develop others. The
recurrence rate is about 3 percent after the first stone and
6 percent after the
second.
-
Diet and lifestyle
A high protein (meat, chicken and fish)
and low fiber (fruits, vegetables and
whole grains) diet may increase the risk of some types of kidney
stones.
A diet that
doesn’t include enough fluids can
do the same, because it may leave higher
concentrations of stone forming substances
in the urine. Similarly, not drinking
enough water while living
in a hot, dry climate, working in a hot
environment, or exercising heavily can
also lead to stones. Finally, people
who are bedridden
or don’t get enough exercise may
develop stones because their bones release
more calcium.
Remember that having one or more risk factors may increase your
chance of developing kidney stones, but it does not mean that
you will get them.
The best preventative measures, especially to prevent recurrence,
may be diet and lifestyle changes. For example, eating more fiber
and less protein, especially meat protein, and drinking more
water may help prevent stone formation. You should talk to your
doctor about this. Your doctor may also prescribe certain medications
to prevent recurrence, depending on the type of stone.
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