Incidence and Prevalence
of Kidney Stones
People who live near large bodies of water (e.g., Great Lakes,
Gulf of Mexico), those who live in "soft" water areas, and
those who have a sibling or parent with the condition
experience a higher incidence of renal stone disease.
According to the U.S. National Institutes of Health, 1 person
in 10 develops kidney stones during their lifetime and renal
stone disease accounts for 7–10 of every 1000 hospital
admissions. Kidney stones are most prevalent in patients
between the ages of 30 and 45, and the incidence declines
after age 50.
Kidney Stone
Causes and Risk Factors
Several factors increase the risk for developing kidney
stones, including inadequate fluid intake and dehydration,
reduced urinary flow and volume, certain chemical levels in
the urine that are too high (e.g., calcium, oxalate, uric
acid) or too low (e.g., citrate), and several medical
conditions. Anything that blocks or reduces the flow of urine
(e.g., urinary obstruction, genetic abnormality) also
increases the risk.
Chemical risk factors include high levels of the following in
the urine:
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Calcium (hypercalciuria)
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Cystine (cystinuria;
caused by a genetic disorder)
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Oxalate (hyperoxaluria)
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Uric acid (hyperuricosuria)
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Sodium (hypernatremia)
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A low level
of citrate is a risk factor for hypocitraturia.
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The following medical conditions are also
risk factors:
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Congenital
kidney defect that may increase urinary calcium loss and
stone formation (medullary sponge kidney)
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Excessive
parathyroid hormone, which causes calcium loss
(hyperparathyroidism)
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Gout (caused
by excessive uric acid in the blood)
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High blood
pressure (hypertension)
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Inflammation
of the colon that causes chronic diarrhea, dehydration,
and chemical imbalances (colitis)
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Inherited
condition in which the kidneys are unable to excrete acid
(renal tubular acidosis)
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Intestinal
disorder that causes chronic diarrhea, dehydration, and
low citrate (Crohn’s disease)
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Painful joint
inflammation (arthritis)
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Urinary tract
infections (affect kidney function)
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Diet plays an important role in the
development of kidney stones, especially in patients who are
predisposed to the condition. A diet high in sodium, fats,
meat, and sugar, and low in fiber, vegetable protein, and
unrefined carbohydrates increases the risk for renal stone
disease. Recurrent kidney stones may form in patients who are
sensitive to the chemical byproducts of animal protein and who
consume large amounts of meat.
High doses of vitamin C (i.e., more than 500
mg per day) can result in high levels of oxalate in the urine
(hyperoxaluria) and increase the risk for kidney stones.
Oxalate is found in berries, vegetables (e.g., green beans,
beets, spinach, squash, tomatoes), nuts, chocolate, and tea.
Stone formers should limit their intake of cranberries, which
contain a moderate amount of oxalate.
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