Kidney Stones in Adults
Kidney stones, one of the most
painful of the urologic disorders, are not a product
of modern life. Scientists have found evidence of
kidney stones in a 7,000-year-old Egyptian mummy.
Unfortunately, kidney stones are one of the most
common disorders of the urinary tract. In 2000,
patients made 2.7 million visits to health care
providers and more than 600,000 patients went to
emergency rooms for kidney stone problems. Men tend
to be affected more frequently than women.
Most kidney stones pass out of
the body without any intervention by a physician.
Stones that cause lasting symptoms or other
complications may be treated by various techniques,
most of which do not involve major surgery. Also,
research advances have led to a better understanding
of the many factors that promote stone formation.
Introduction to the
Urinary Tract
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The urinary tract |
The urinary tract, or system,
consists of the kidneys, ureters, bladder, and
urethra. The kidneys are two bean-shaped organs
located below the ribs toward the middle of the
back. The kidneys remove extra water and wastes from
the blood, converting it to urine. They also keep a
stable balance of salts and other substances in the
blood. The kidneys produce hormones that help build
strong bones and help form red blood cells.
Narrow tubes called ureters
carry urine from the kidneys to the bladder, an
oval-shaped chamber in the lower abdomen. Like a
balloon, the bladder's elastic walls stretch and
expand to store urine. They flatten together when
urine is emptied through the urethra to outside the
body.
What is a kidney
stone?
A kidney stone is a hard mass
developed from crystals that separate from the urine
and build up on the inner surfaces of the kidney.
Normally, urine contains chemicals that prevent or
inhibit the crystals from forming. These inhibitors
do not seem to work for everyone, however, so some
people form stones. If the crystals remain tiny
enough, they will travel through the urinary tract
and pass out of the body in the urine without being
noticed.
Kidney stones may contain
various combinations of chemicals. The most common
type of stone contains calcium in combination with
either oxalate or phosphate. These chemicals are
part of a person's normal diet and make up important
parts of the body, such as bones and muscles.
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A less common type of stone is
caused by infection in the urinary tract. This type
of stone is called a struvite or infection stone. A
bit less common is the uric acid stone. Cystine
stones are rare.
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Kidney stones in kidney, ureter, and bladder |
Urolithiasis is the medical
term used to describe stones occurring in the
urinary tract. Other frequently used terms are
urinary tract stone disease and nephrolithiasis.
Doctors also use terms that describe the location of
the stone in the urinary tract. For example, a
ureteral stone (or ureterolithiasis) is a kidney
stone found in the ureter. To keep things simple,
however, the term "kidney stones" is used throughout
this fact sheet.
Gallstones and kidney stones
are not related. They form in different areas of the
body. If you have a gallstone, you are not
necessarily more likely to develop kidney stones.
Who gets kidney
stones?
For unknown reasons, the
number of people in the United States with kidney
stones has been increasing over the past 30 years.
The prevalence of stone-forming disease rose from
3.8 percent in the late 1970s to 5.2 percent in the
late 1980s and early 1990s. White Americans are more
prone to develop kidney stones than African
Americans. Stones occur more frequently in men. The
prevalence of kidney stones rises dramatically as
men enter their 40s and continues to rise into their
70s. For women, the prevalence of kidney stones
peaks in their 50s. Once a person gets more than one
stone, others are likely to develop.
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