Gallstones and Kidneystones

Gallstones and kidney stones are both relatively common problems that plague people in our society. Kidney stones most commonly consist of calcium and occur in patients who excrete high levels of calcium into the urine. Other causes of kidney stones include gout (because of high levels of uric acid in the urine), and certain chronic urinary infections (which can alter the pH of the urine).

Gallstones are caused by entirely different mechanisms than kidney stones. The most common type of gallstone is composed of cholesterol. These stones occur because bile in the gallbladder develops high concentrations of cholesterol and low concentrations of the substances, such as bile acids, that keep stones from forming. Other stones are a combination of calcium and bile pigments (formed from the destruction of old red blood cells). These typically occur in people who have a rapid destruction of their blood cells, such as patients with sickle-cell anemia. The third major type of gallstone is the brown pigment stone, formed by calcium and bilirubin because of infection of the bile. Interestingly, although two of the three types of gallstones have calcium in them, they are not related to high blood levels of calcium (unlike kidney stones).

Several factors are known to be associated with a greater likelihood of forming gallstones: female gender, obesity, rapid weight loss, pregnancy, older age and use of certain medications, such as those containing estrogens. While kidney stones and gallstones are not related in the vast majority of cases, there may be a connection in a few people. One example is Crohn's disease -- a chronic inflammatory condition of the small and large intestine. Patients with Crohn's may get kidney stones because they can absorb large amounts of oxalate from their colon. Oxalate combines with calcium in the kidneys to form stones. They also can get gallstones because of a lowered capacity to absorb bile acids in their small intestine. The reduction in bile acids allows cholesterol in the gallbladder to collect and form stones.

Regardless of the cause, patients who have pain or other symptoms related to kidney stones or gallstones should be evaluated by a doctor to determine if any further action needs to be taken.