Gallstones
What Causes Gallstones?
What Causes Gallstones?
There are two types of gallstones; 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.
Cholesterol Stones
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.
Pigment Stones
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, in which too much bilirubin is formed.
Other Factors
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 the 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 rate 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.
Who is at risk for gallstones?
- women
- people over age 60
- Native Americans
- Mexican Americans
- overweight men and women
- people who fast or lose a lot of weight quickly
- pregnant women, women on hormone replacement therapy, and women who use birth control
pills