why do you get gallstones

Gallstones form primarily due to an imbalance in the substances that make up bile, a digestive fluid stored in the gallbladder. The two main types of gallstones are cholesterol stones and pigment stones. Cholesterol gallstones form when bile contains too much cholesterol and not enough bile salts to keep the cholesterol dissolved. Excess cholesterol precipitates out as crystals, which then grow into stones. This process can be influenced by genetic factors, excessive cholesterol secretion by the liver, and impaired gallbladder motility, which can prevent the proper emptying of bile and allow stones to form. High estrogen levels, such as during pregnancy or hormone therapy, can increase cholesterol levels in bile and reduce gallbladder movement, contributing to stone formation. Pigment stones form from excess bilirubin, a breakdown product of red blood cells. This type is more common in people with certain medical conditions that increase red blood cell destruction (like sickle cell disease or some infections) and liver diseases. If the gallbladder does not empty properly or bile becomes overly concentrated, this can also promote gallstone formation. Risk factors include age, female sex, obesity, family history, rapid weight loss, diabetes, and certain ethnicities (e.g., Native American, Hispanic). Other factors like biliary infections, certain medical treatments, and metabolic disorders may also contribute. In summary, gallstones develop when bile chemistry is disturbed—either by too much cholesterol or bilirubin—and when gallbladder function is impaired, leading to the precipitation of these substances into stones.