Causes and Symptoms of Gallstones

The gallbladder is a small pear-shaped organ located beneath the liver on the right side of the abdomen. The gallbladder's primary functions are to store and concentrate bile, and to secrete bile through small ducts into the small intestine to help digest food. Bile, a fluid produced by the liver, contains water, cholesterol, lipids (fats), bile salts (natural detergents that break up fat), and the bile pigment bilirubin.

What are Gallstones?

Gallstones are hard crystal-like particles that form in the gallbladder from substances in bile. Cholesterol stones are usually white or yellow and account for about 80% of gallstones. The other 20% of gallstones are small dark pigment stones made of bilirubin and calcium salts. Risk factors for pigment stones include cirrhosis, biliary tract infections, and hereditary blood cell disorders like sickle cell anemia.

Gallstones may be as small as a grain of sand or as large as a golf ball. The gallbladder may develop a single large stone or many smaller ones, even several thousand.

What Causes Gallstones?

Gallstones may be caused by a combination of factors, including inherited body chemistry, body weight, gallbladder motility (movement), and perhaps diet.

Cholesterol gallstones develop when bile contains too much cholesterol and not enough bile salts. Two other factors seem to be important in causing gallstones. The first is how often and how well the gallbladder contracts; incomplete and infrequent emptying of the gallbladder may cause the bile to become over-concentrated and contribute to gallstone formation. The second factor is the presence of proteins in the liver and bile that either promote or inhibit cholesterol crystallization into gallstones.

Other factors also seem to play a role in causing gallstones, but just how these contribute is not clear. Obesity has been shown to be a major risk factor for gallstones. A large clinical study showed that being even moderately overweight increases one's risk for developing gallstones. This is probably because obesity tends to cause excess cholesterol in bile, low bile salts, and decreased gallbladder emptying. Very low calorie, rapid weight-loss diets, and prolonged fasting seem also to cause gallstone formation.

In addition, increased levels of the hormone estrogen as a result of pregnancy, hormone therapy, or the use of birth control pills, may increase cholesterol levels in bile and decrease gallbladder movement, resulting in gallstone formation.

No clear relationship has been proven between diet and gallstone formation. However, low-fiber, high-cholesterol diets, and diets high in starchy foods have been suggested as contributing to gallstone formation.

Who Is at Risk for Gallstones?

This year, more than 1 million people in the United States will learn they have gallstones. They will join the estimated 20 million Americans who already have gallstones.

Those who are most likely to develop gallstones are:

• Women between 20 and 60 years of age; they are twice as likely to develop gallstones than men.
• Men and women over age 60.
• Pregnant women or women who have used birth control pills or estrogen replacement therapy.
• Native Americans. They have the highest prevalence of gallstones in the United States. A majority of Native American men have gallstones by age 60. Among the Pima Indians of Arizona, 70% of women have gallstones by age 30.
• Mexican-American men and women of all ages.
• Men and women who are overweight.
• People who go on "crash" diets or who lose a lot of weight quickly.

What are the Symptoms of Gallstones?

Most people with gallstones do not have symptoms. They have what are called silent stones and require no treatment. Silent stones usually are detected during a routine medical checkup or examination for another illness.

A gallstone attack usually is marked by a steady, severe pain in the upper abdomen. Attacks may last only 20 or 30 minutes but more often they last for one to several hours. A gallstone attack may also cause nausea or vomiting, or pain between the shoulder blades, or in the right shoulder. Attacks may be separated by weeks, months, or even years. Once a true attack occurs, subsequent attacks are much more likely.

Blockage of the cystic duct is a common complication. Gallstones that become lodged in the cystic duct and block the flow of bile cause cholecystitis, an inflammation of the gallbladder.

A less common but more serious problem occurs when gallstones become lodged in the bile ducts between the liver and intestine. This blocks bile flow from the gallbladder and liver, causing pain and jaundice. Gallstones may also interfere with the flow of digestive fluids secreted from the pancreas into the small intestine, leading to pancreatitis, an inflammation of the pancreas. Prolonged blockage of any of these ducts can cause severe damage to the gallbladder, liver, or pancreas, which can be fatal. Warning signs include fever, jaundice, and persistent pain.

For more information see: Diagnosis and Treatment of Gallstones

Each year, Medical College of Wisconsin physicians care for more than 180,000 patients, representing nearly 500,000 patient visits. Medical College physicians practice at Children's Hospital of Wisconsin, Froedtert Memorial Lutheran Hospital, the Milwaukee VA Medical Center, and many other hospitals and clinics in Milwaukee and southeastern Wisconsin.