Which of the following laboratory findings best distinguishes intravascular hemolysis from extravascular hemolysis?
- A Elevated serum LDH
- B Hemoglobinuria with markedly reduced serum haptoglobin ✓
- C Reticulocytosis and hyperbilirubinemia
- D Spherocytes on peripheral smear
Correct answer: B. Hemoglobinuria with markedly reduced serum haptoglobin
Explanation
Free hemoglobin released into the plasma during intravascular hemolysis saturates and depletes haptoglobin (its carrier), and the excess is filtered by the kidney producing hemoglobinuria — a feature specific to intravascular hemolysis. Elevated LDH, reticulocytosis, and indirect hyperbilirubinemia occur in both intravascular and extravascular hemolysis. Spherocytes are characteristically seen in extravascular hemolytic conditions such as hereditary spherocytosis and autoimmune hemolytic anemia.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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