Gallstones are crystal-like deposits that develop in the gallbladder — a small, pear-shaped organ that stores bile, a digestive fluid produced by the liver.
These deposits may be as small as a grain of sand or as large as a golf ball; they may be hard or soft, smooth or jagged. You may have several gallstones or just one.
Some 30 million American adults suffer from gallstones. Yet most of those who have the condition do not realize it. In this case, what you don’t know probably won’t hurt you; gallstones that are simply floating around inside the gallbladder generally cause no symptoms and no harm.
These “silent" stones usually go unnoticed unless they show up in an ultrasound exam conducted for some other reason. However, the longer a stone exists in the gallbladder, the more likely it is to become problematic. People who have gallstones without symptoms have 20% chance of having an episode of pain during their lifetime.
When symptoms do occur, it’s usually because the gallstone has moved and become lodged within a duct that carries bile, such as the cystic duct, a small conduit that connects the gallbladder to another tube called the common bile duct. The typical symptom is abdominal pain, perhaps accompanied by nausea, indigestion, or fever. The pain, caused by the gallbladder’s contraction against the lodged stone, generally occurs within an hour of eating a large meal or in the middle of the night. Stones can also clog the common bile duct, which carries bile into the small intestine, and the hepatic ducts, which take bile out of the liver.
Obstructions in the bile pathway may cause a duct to become inflamed and possibly infected. Blockage of the common bile duct, which merges with the pancreatic duct at the small intestine, can also lead to inflammation of the pancreas (gallstone pancreatitis).
In a rare but dangerous condition that occurs most often in older women, gallstones migrate into the small intestine and block the passageway into the large intestine; symptoms include severe and frequent vomiting. Although gallstones are present in about 80% of people with gallbladder cancer, it is uncertain whether gallstones play a role, except when really large stones (greater than 3 centimeters in diameter) are present.
About a million new cases of gallstones are diagnosed in the U.S. each year. For reasons that are still unclear, women are two times more likely than men to be afflicted. Native Americans have the highest rates of gallstones in the U.S. because they have a genetic disposition to secrete high levels of cholesterol in bile (a contributing factor to gallstones.) Mexican-Americans also have high rates of gallstones.
Gallstones are also more common in people over age 60, in those who are obese or have lost a lot of weight in a short amount of time, in those who have diabetes or sickle cell disease, and in women who have had multiple pregnancies and who take hormone replacement therapy or birth control pills.
What Causes Gallstones?
The primary function of the gallbladder is to store bile, a brown or yellowish fluid that helps the body break down fatty food. When you eat a meal, the gallbladder releases its stored bile into the cystic duct. From there the fluid passes through the common bile duct and into the small intestine to mix with food.
Chief among the ingredients of bile are cholesterol and bile acids. Normally, the concentration of bile acids is high enough to break down the cholesterol in the mixture and keep it in liquid form. However, a diet high in fat can tip this delicate balance, causing the liver to produce more cholesterol than the bile acids are able to handle. As a result, some of this excess cholesterol begins to solidify into crystals, which we call gallstones. About 80% of all gallstones are called cholesterol stones and are created this way. The remaining 20% consist of calcium mixed with the bile pigment bilirubin and are called pigment stones. Sickle cell and other blood disorders where red blood cells are destroyed can often lead to pigment gallstones
Gallstones can form even in people who eat properly. And as researchers have found, a diet extremely low in fat can also contribute to gallstone formation: With little fatty food to digest, the gallbladder is called into play less frequently than usual, so the cholesterol has more time to solidify. Other factors that can reduce activity in the gallbladder, possibly leading to gallstone formation, include cirrhosis, the use of birth control pills or hormone replacement therapy, and pregnancy.
Family history, diabetes, sudden weight loss, and cholesterol drugs, and older age can also increase risk for gallstones.
- The Mayo Clinic.
- National Digestive Disease Informational Clearinghouse.
- Colorado Center for Digestive Disorders.
- American Liver Foundation.
- Annals of Surgery: “Gallstones."