The Facts
A kidney stone is formed when a small speck of mineral settles out of the
urine into the kidney or the ureter, a tube that links the kidney to
the bladder. Additional minerals will stick to the small speck and over
time will develop into stones. The most common kidney stones are composed of
calcium oxalate, which is naturally present in the urine. Other chemicals
making up kidney stones are uric acid, cystine, or methionine.
The stones are often small and can pass through the urinary system on their
own. Kidney stones are more likely to form in hot climates or in the summer
time. When people become dehydrated, the minerals in their urine become more concentrated.
It then becomes easier for small mineral particles to settle out of the urine
and start a kidney stone. Kidney stones are three times more common in men than
in women. They also seem to run in families. People who have already had one
kidney stone also have a higher than average risk of getting another.
Causes
There is no known cause for kidney stones, although dehydration is a key risk factor.
Kidney stones can also be caused by an imbalance in a person's metabolism causing
abnormally high levels of mineral salts to collect in the urine. Stones made
up of uric acid occur in people who have diseases such as gout,
chronic dehydration, and some cancers.
Hyperparathyroidism, a condition in which the parathyroid gland is overactive,
can also be linked to kidney stones. In addition, certain disorders of the bowel or intestines can also lead to kidney stones, as can a chronic bacterial infection of the
urinary system.
