Gallstones are solid, stone-like materials that develop in the gallbladder. The gallbladder is a small, pear-shaped sac located under the liver in the right side of the abdomen, which stores and secretes bile.
Bile is a liquid made in the liver to help body digests fats. It contains water, cholesterol, fats, bile salts, and bilirubin – a waste product. Gallstones form when bile stored in the gallbladder hardens into pieces of stone-like material.
There are two types of gallstones: cholesterol gallstones and pigment gallstones. Cholesterol gallstones are usually yellow-green and are made primarily of hardened cholesterol. They are the most common type of gallstones, accounting for about 80 percent of all gallstones cases.
Pigment gallstones are small, dark brown to black stones that made of bilirubin. The gallstones can range in size from very small to as large as a ping pong ball. They account for the other 20% of gallstones cases.
What Causes the Gallstones?
Cholesterol gallstones are believed to form when bile contains too much cholesterol, or not enough bile salts, or when the gallbladder does not empty as it should for some other reason.
The exact causes of pigment gallstones are still unclear but they tend to develop in people with cirrhosis, biliary tract infections or hereditary blood disorders such as sickle cell anemia.
Risk Factors for Gallstones
Risk factors that contribute to the formation of gallstones include:
People who over the age of 60 are at higher risk of developing gallstones than younger people as their body tend to secrete more cholesterol into bile, which can lead to gallstones.
Women who aged between 20 and 60 years are more likely to develop gallstones than men. Excess estrogen in women during pregnancy and birth control pills appears to increase cholesterol levels in bile and decrease gallbladder movement.
American Indians have a higher risk for gallstones than Asian and African descent. In fact, the majority of American Indian men have gallstones by the age of 60. Mexican American are also have high rates of gallstones.
Obesity is a major risk factor for gallstones, especially in women. A large clinical study has shown 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.
People with diabetes generally have high levels of fatty acids called triglycerides. These fatty acids may increase the risk of gallstones.
- Rapid weight loss
Rapid weight loss causes the liver to secrete extra cholesterol into bile, and thus can lead to gallstones.
- Cholesterol-lowering drugs
Drugs that lower cholesterol levels actually increase the amount of cholesterol secreted into bile, thereby increasing the risk of gallstones.