Gallstones form when liquid stored in the gallbladder hardens into
pieces of stone-like material. The liquid, called bile, is used to help
the body digest fats. Bile is made in the liver, then stored in the
gallbladder until the body needs to digest fat. At that time, the
gallbladder contracts and pushes the bile into a tube-called a
duct-that carries it to the small intestine, where it helps with
digestion.
Bile contains water, cholesterol.html">cholesterol,
fats, bile salts, and bilirubin. Bile salts break up fat, and bilirubin
gives bile and stool a brownish color. If the liquid bile contains too
much cholesterol, bile salts, or bilirubin, it can harden into stones.
The two types of gallstones are cholesterol stones and pigment
stones. Cholesterol stones are usually yellow-green and are made
primarily of hardened cholesterol. They account for about 80 percent of
gallstones. Pigment stones are small, dark stones made of bilirubin.
Gallstones can be as small as a grain of sand or as large as a golf
ball. The gallbladder can develop just one large stone, hundreds of
tiny stones, or almost any combination.
Gallstones can block the normal flow of bile if they lodge in any of
the ducts that carry bile from the liver to the small intestine. That
includes the hepatic ducts, which carry bile out of the liver; the
cystic duct, which takes bile to and from the gallbladder; and the
common bile duct, which takes bile from the cystic and hepatic ducts to
the small intestine. Bile trapped in these ducts can cause inflammation
in the gallbladder, the ducts, or, rarely, the liver. Other ducts open
into the common bile duct, including the pancreatic duct, which carries
digestive enzymes out of the pancreas. If a gallstone blocks the
opening to that duct, digestive enzymes can become trapped in the
pancreas and cause an extremely painful inflammation called
pancreatitis.
If any of these ducts remain blocked for a significant period of
time, severe-possibly fatal-damage can occur, affecting the
gallbladder, liver, or pancreas. Warning signs of a serious problem are
fever, jaundice, and persistent pain.
Scientists believe cholesterol stones form when bile contains too
much cholesterol, too much bilirubin, or not enough bile salts, or when
the gallbladder does not empty as it should for some other reason.
The cause of pigment stones is uncertain. They tend to develop in
people who have cirrhosis, biliary tract infections, and hereditary
blood disorders such as sickle cell anemia.
It is believed that the mere presence of gallstones may cause more
gallstones to develop. However, other factors that contribute to
gallstones have been identified, especially for cholesterol stones.
- Obesity - Obesity is a
major risk factor for gallstones, especially in women. A large clinical
study showed that being even moderately overweight increases one's risk
for developing gallstones. The most likely reason is that obesity tends
to reduce the amount of bile salts in bile, resulting in more
cholesterol. Obesity also decreases gallbladder emptying. - Estrogen -
Excess estrogen from pregnancy, hormone replacement therapy, or birth
control pills appears to increase cholesterol levels in bile and
decrease gallbladder movement, both of which can lead to gallstones. - Ethnicity -
Native Americans have a genetic predisposition to secrete high levels
of cholesterol in bile. In fact, they have the highest rates of
gallstones in the United States. A majority of Native American men have
gallstones by age 60. Among the Pima Indians of Arizona, 70 percent of
women have gallstones by age 30. Mexican-American men and women of all
ages also have high rates of gallstones. - Gender - Women between 20 and 60 years of age are twice as likely to develop gallstones as men.
- Age - People over age 60 are more likely to develop gallstones than younger people.
- Cholesterol-lowering drugs -
Drugs that lower cholesterol levels in blood actually increase the
amount of cholesterol secreted in bile. This in turn can increase the
risk of gallstones. - Diabetes -
People with diabetes generally have high levels of fatty acids called
triglycerides. These fatty acids increase the risk of gallstones. - Rapid weight loss -
As the body metabolizes fat during rapid weight loss, it causes the
liver to secrete extra cholesterol into bile, which can cause
gallstones. - Fasting - Fasting decreases gallbladder
movement, causing the bile to become overconcentrated with cholesterol,
which can lead to gallstones.
Symptoms of gallstones are often called a gallstone "attack" because they occur suddenly. A typical attack can cause:
- Steady, severe pain in the upper abdomen that increases rapidly and lasts from 30 minutes to several hours.
- Pain in the back between the shoulder blades.
- Pain under the right shoulder.
- Nausea or vomiting.
Gallstone attacks often follow fatty meals, and they may occur duringthe night. Other gallstone symptoms include:
- Abdominal bloating.
- Recurring intolerance of fatty foods.
- Colic.
- Belching.
- Gas.
- Indigestion.
People who also have the following symptoms should see a doctor right away:
- Sweating.
- Chills.
- Low-grade fever.
- Yellowish color of the skin or whites of the eyes.
- Clay-colored stools.
Many people with gallstones have no symptoms. These patients are
said to be asymptomatic, and these stones are called "silent stones."
They do not interfere in gallbladder, liver, or pancreas function and
do not need treatment.
Many gallstones, especially silent stones, are discovered by
accident during tests for other problems. But when gallstones are
suspected to be the cause of symptoms, the doctor is likely to do an
ultrasound exam.
Gallstone symptoms are similar to those of heart attack,
appendicitis, ulcers, irritable bowel syndrome, hiatal hernia,
pancreatitis, and hepatitis. So accurate diagnosis is important.
Surgery to remove the gallbladder is the most common way to treat
symptomatic gallstones. (Asymptomatic gallstones usually do not need
treatment.) Each year more than 500,000 Americans have gallbladder
surgery. The surgery is called cholecystectomy.
Nonsurgical approaches are used only in special situations-such as
when a patient's condition prevents using an anesthetic-and only for
cholesterol stones. Stones recur after nonsurgical treatment about half
the time.
Fortunately, the gallbladder is an organ that people can live
without. Losing it won't even require a change in diet. Once the
gallbladder is removed, bile flows out of the liver through the hepatic
ducts into the common bile duct and goes directly into the small
intestine, instead of being stored in the gallbladder. However, because
the bile isn't stored in the gallbladder, it flows into the small
intestine more frequently, causing diarrhea in some people. Also, some
studies suggest that removing the gallbladder may cause higher blood
cholesterol levels, so occasional cholesterol tests may be necessary.
