Intravascular hemolysis is caused by mechanical injury, complement fixation, intracellular parasites or exogenous toxic factors. Which statement best describes this?

• A. It results in hemoglobinemia and hemoglobinuria
• B. It primarily causes splenomegaly
• C. It does not cause hemoglobinemia
• D. It is always autoimmune

Answer: (A)

Destruction of red cells inside the vessels releases free hemoglobin into the plasma and then into the urine, so you see hemoglobinemia and hemoglobinuria. That intravascular process contrasts with extravascular hemolysis, where RBCs are removed mainly by splenic macrophages, often leading to splenomegaly rather than prominent hemoglobinemia. So the hallmark consequence is the presence of free hemoglobin in blood and urine. It can be immune- or nonimmune-mediated, but it is not restricted to autoimmune cases, and it does not primarily cause splenomegaly, nor does it lack hemoglobinemia.