Certified Neuroscience Registered Nurse (CNRN) Practice Exam

Which gallstone type results primarily from the breakdown of bilirubin?

1. Cholesterol gallstones

2. Mixed gallstones

3. Pigmented gallstones

4. Calcium stones

The correct answer is: Pigmented gallstones

The type of gallstone that results primarily from the breakdown of bilirubin is pigmented gallstones. These stones are most commonly composed of calcium bilirubinate, which forms when there is an excess of bilirubin in the bile. Bilirubin is a byproduct of red blood cell breakdown, and when the liver metabolizes this substance, excess amounts can lead to the formation of these dark-colored stones. Pigmented gallstones are often associated with conditions that cause increased hemolysis (the breakdown of red blood cells), such as hemolytic anemia or liver cirrhosis. In these conditions, the liver processes more bilirubin than normal, leading to its increased concentration in bile. As a result, the biliary system becomes saturated with bilirubin, primarily leading to the development of pigmented gallstones. Other types of gallstones, like cholesterol gallstones, are primarily composed of crystallized cholesterol and typically form in the presence of supersaturated bile, high levels of cholesterol, or reduced bile salts. Mixed gallstones contain a combination of cholesterol and bilirubin, but they are not predominantly formed from bilirubin breakdown. Calcium stones relate to a broader classification of mineral-based stones and do not specifically link to bilirubin metabolism and production. Thus,