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Most
people with kidney stones will have calcium
oxalate with either elevated calcium,
oxalate, and/or uric acid levels and low
citrate levels. They will not have any
other causes. However, a minority of
people will have non- genetic medical
conditions causing stone formation (Genetic
Causes of Kidney Stones is discussed
elsewhere.) The medical conditions
include the following:
Hyperparathyroidism:
The
parathyroid glands are located in the neck
next to the thryoid gland, hence its name.
Parathyroid hormone regulates blood calcium
and phosphate levels. Most cases of
hyperparathyroidism are of the non-genetic
form and develop in adults (Medical
Causes of Kidney Stones).
Not everyone with this disorder develops
kidney stones. Other complications include
osteoporosis. This disorder can be suspected
if blood calcium levels are elevated and
phophate levels are low. Confirmation
is made by directly measuring parathyroid
hormone levels in the blood. Treatment
sometimes requires surgical removal of the
thyroid gland. Unfortunately, even
after removing the parathyroid gland many
people can continue to form stones.
Medullary
Sponge Kidney: The
kidneys consist of an outer cortical layer
and an inner medullary region. The
medulla consists of small tubules which
carry urinary fluid as it is processed in
the kidney. In sponge kidney, these
tubules become dilated. The kidney
takes on a spongey appearance.
Crystals form in these dilated tubules which
lead to formation of kidney stones. In
some, the medulla contains millions of
calcium crystals. The reason for
crystal formation may be due to stasis of
urine in the tubules. In addition, the
changes in the tubules may lead to increased
calcium excretion into the urine (hypercalciuria)
and renal tubular acidosis. Medullary
sponge kidney can effect one kidney more
than the other. In some patients
stones seem to only occur on one side.
Additionally, there may be an increased risk
for kidney infections.
Sarcoidosis:
This
is an autoimmune disorder which is most
common in African Americans, but does occur
in all ethnic groups. People with this
disorder have abnormal growth of lymph
nodes particularly in the chest around the
lungs. These lymph nodes produce
vitamin D which causes increased absorption
of calcium from the diet. This is the
reason vitamin D is added to milk, to
increase calcium absorption. The
increased calcium absorbed from food is
excreted in the urine. This raises
urine calcium levels causing calcium
crystals and stones to precipitate and form.
Treatment often requires prednisone.
Renal
Tubular Acidosis (RTA):
This disorder can develop as a consequence
of certain autoimmune diseases such as
Sjogren's syndrome. There are also
genetic causes discussed in Genetic
Causes of Kidney Stones. People with
this disorder cannot pump acid which
builds up in the body into the urine.
Therefore, the urine has a high pH (i.e. not
acidic) causing calcium phosphate crystals
to precipitate and form into calcium
phosphate stones. Calcium
phosphate does not form crystals in acidic
urine. Treatment includes bicarbonate or
citrate therapy to reduced the body's
acidity.
(NIDDK Info Sheet)
Chronic
Myelogenous Leukemia (CML):
This
is a chronic blood disorder with high levels
of white blood cells. It is associated
with high levels of urinary uric acid which form into stones. Treatment
includes decreasing the levels of white
blood cells, maximizing water/fluid
consumption, and possibly allopurinol and
bicarbonate/citrate therapy.
Diarrhea/Ileostomy:
Large
losses of fluid from the gastrointestinal
tract can lead to dehydration and loss of
bicarbonate and potassium. This leads
to small urine volumes and low
urinary citrate levels. Both calcium
and uric acid stones can form. Therapy
is directed to decrease gastrointestinal
fluid losses, increase urine volume and oral
citrate therapy. These stones are often
very difficult to prevent without decreases
in diarrhea/ileostomyl losses.
Crohn's
Disease and Ulcerative Colitis:
Calcium
oxalate stones and uric acid stones can
form. Patients with these disorders
can develop decreased fat absorption in the
gut and increased oxalate absorption.
Treatment includes steroids to treat the
inflammatory disorder and calcium.
Calcium binds to oxalate in the gut to
prevent it from being absorbed into the
body. Absorbed oxalates will
eventually be excreted in the urine and lead
to stones. Oxalate are contained in food,
so the calcium is taken with food.
Uric acid stones form from low urine volume
and decreased urine citrate levels as
described above for diarrhea.
Urinary
Tract Infections:
Urinary tract infections can cause kidney
stones or complicate pre-existing stones.
This is discussed in more detail in the Infections
and Kidney Stones section.
Gout:
Gout is associated with both uric acid and
calcium stones. Refer to
Gout information
page.
Medications:
Many
medicaitons used to treat common conditions
can lead to kidney stones. Although
acetazolamide is used in treatment of uric
acid stones, it can lead to calcium
phosphate stones. Topamax (topiramate) is
used for seizures and migraine headaches.
It has physical characteristics in common
with acetazolamide. Topamax can lead
to high urine pH and very low citrate
levels. Triamterene used in some blood
pressure medication can also contribute to
kidney stone formation.
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