Cholesterol StonesScientists 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.
Pigment StonesThe 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.
Other FactorsIt 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
- 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.
Reprinted from the National Digestive Diseases Information Clearinghouse (NDDIC)
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