Gall stones are composed of all except:
**Core Concept**
Gallstones are solid particles that form in the gallbladder, composed of various substances that precipitate out of bile. The formation of gallstones is influenced by factors such as bile composition, gallbladder motility, and genetic predisposition.
**Why the Correct Answer is Right**
Gallstones can be classified into several types based on their composition, including cholesterol stones, pigment stones, and mixed stones. Cholesterol stones are the most common type and are composed of cholesterol, bile salts, and other substances. Pigment stones, on the other hand, are composed of bilirubin, which is a breakdown product of hemoglobin. Mixed stones contain a combination of cholesterol and pigment.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because cholesterol stones are a common type of gallstone.
**Option B:** Incorrect because pigment stones are another type of gallstone.
**Option C:** Incorrect because mixed stones contain a combination of cholesterol and pigment.
**Clinical Pearl / High-Yield Fact**
It's essential to note that gallstones can cause symptoms such as biliary colic, jaundice, and pancreatitis, and may require surgical or endoscopic removal.
**Correct Answer: D.