Ursodiol reduces the size of common bile duct gallstones by wof mechanisms
**Core Concept**
Ursodiol, also known as ursodeoxycholic acid, is a bile acid that plays a crucial role in dissolving and reducing the size of cholesterol gallstones. This process is mediated through its ability to solubilize cholesterol and decrease the cholesterol saturation index in bile.
**Why the Correct Answer is Right**
Ursodiol reduces the size of common bile duct gallstones by two primary mechanisms:
* It increases the solubility of cholesterol in bile by converting cholesterol into a more soluble form, thereby reducing the cholesterol saturation index.
* It also increases the secretion of phospholipids and lecithin into bile, which helps to solubilize cholesterol and prevent its precipitation.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not accurately describe the mechanism by which ursodiol reduces the size of gallstones.
**Option B:** This option is incorrect as it is not a recognized mechanism of action for ursodiol in the context of gallstone dissolution.
**Option C:** This option is incorrect as it is not a mechanism by which ursodiol reduces the size of gallstones.
**Clinical Pearl / High-Yield Fact**
Ursodiol is typically used for the dissolution of small to medium-sized cholesterol gallstones, and it is most effective when the cholesterol saturation index in bile is high.
**Correct Answer: C. It decreases the cholesterol saturation index in bile and increases the secretion of phospholipids and lecithin into bile.**