| Doctors do not always know what
causes a stone to form. While certain foods may promote stone formation in people who are
susceptible, scientists do not believe that eating any specific food causes stones to form
in people who are not susceptible. A person
with a family history of kidney stones may be more likely to develop stones. Urinary tract
infections, kidney disorders such as cystic kidney diseases, and metabolic disorders such
as hyperparathyroidism are also linked to stone formation.
In addition, more than 70 percent of people with a rare
hereditary disease called renal tubular acidosis develop kidney stones.
Cystinuria and hyperoxaluria are two other rare, inherited
metabolic disorders that often cause kidney stones. In cystinuria, too much of the amino
acid cystine, which does not dissolve in urine, is voided. This can lead to the formation
of stones made of cystine. In patients with hyperoxaluria, the body produces too much of
the salt oxalate. When there is more oxalate than can be dissolved in the urine, the
crystals settle out and form stones.
Absorptive hypercalciuria occurs when the body absorbs too
much calcium from food and empties the extra calcium into the urine. This high level of
calcium in the urine causes crystals of calcium oxalate or calcium phosphate to form in
the kidneys or urinary tract.
Other causes of kidney stones are hyperuricosuria (a disorder
of uric acid metabolism), gout, excess intake of vitamin D, and blockage of the urinary
tract. 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.
Calcium oxalate stones may also form in people who have a
chronic inflammation of the bowel or who have had an intestinal bypass operation, or
ostomy surgery. As mentioned above, struvite stones can form in people who have had a
urinary tract infection. People who take the protease inhibitor indinavir, a drug used to
treat HIV infection and AIDS, are at risk of developing kidney stones. www.niddk.nih.gov |
