All are causes of Unconjugated hyperbilirubinemia except.
**Core Concept**
Unconjugated hyperbilirubinemia refers to an elevated level of unconjugated (indirect) bilirubin in the blood. This occurs due to an imbalance in the production, uptake, or conjugation of bilirubin, leading to its accumulation in the bloodstream.
**Why the Correct Answer is Right**
Unconjugated bilirubin is produced in the liver from the breakdown of heme-containing proteins such as hemoglobin. It is then transported to the liver via the bloodstream, where it is either conjugated with glucuronic acid to form water-soluble conjugated bilirubin, or it can be recycled back into the bloodstream. Causes of unconjugated hyperbilirubinemia include increased production of bilirubin (e.g., hemolysis), decreased uptake of bilirubin by the liver (e.g., liver dysfunction), or decreased conjugation of bilirubin (e.g., Gilbert syndrome).
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is actually a cause of unconjugated hyperbilirubinemia. For example, hemolysis can lead to increased production of bilirubin, resulting in unconjugated hyperbilirubinemia.
**Option B:** This option is incorrect because it is actually a cause of conjugated hyperbilirubinemia. Obstruction of the bile ducts, for instance, can lead to a buildup of conjugated bilirubin in the blood.
**Option C:** This option is incorrect because it is actually a cause of conjugated hyperbilirubinemia. Liver cirrhosis can lead to impaired conjugation of bilirubin, resulting in conjugated hyperbilirubinemia.
**Option D:** This option is incorrect because it is actually a cause of conjugated hyperbilirubinemia. Obstruction of the bile ducts, for instance, can lead to a buildup of conjugated bilirubin in the blood.
**Clinical Pearl / High-Yield Fact**
Remember the mnemonic "Gilbert syndrome" to associate with unconjugated hyperbilirubinemia: G - Gilbert, I - Increased, L - Liver, B - Bilirubin, E - Excretion, R - Reduced, T - Transport, S - Syndrome.
**Correct Answer: A. Hemolysis**