Febrile nonhemolytic transfusion reaction vs acute hemolytic transfusion reaction: distinguishing features.

• A. Febrile nonhemolytic: fever without hemolysis; acute hemolytic: fever, chills, hypotension, hemoglobinemia
• B. Febrile nonhemolytic: fever with hemolysis
• C. Febrile nonhemolytic: hypotension; acute: fever
• D. Febrile nonhemolytic: bleeding; acute: no bleeding

Answer: (A)

The main idea is to tell apart febrile nonhemolytic transfusion reaction from acute hemolytic transfusion reaction by whether red blood cell destruction (hemolysis) is happening. Febrile nonhemolytic transfusion reaction presents with fever during or soon after transfusion but shows no evidence of hemolysis—no hemoglobinemia and no signs specifically pointing to red cell destruction. The fever is thought to stem from cytokines released by donor leukocytes or from recipient antibodies reacting with donor leukocytes, not from red cell breakdown.

In contrast, acute hemolytic transfusion reaction is an immune-mediated attack on donor red cells, so you see fever plus clear signs of intravascular hemolysis. That includes chills, hypotension from circulatory shock, hemoglobinemia, dark urine due to hemoglobinuria, and laboratory evidence of hemolysis such as elevated LDH and bilirubin with low haptoglobin. This combination of fever with evidence of hemolysis helps distinguish it from FNHTR.

So the correct way to think about the choices is: FNHTR is fever without hemolysis; AHTR is fever with hemolysis signs like hemoglobinemia and hypotension. The other options don’t fit because they pair FNHTR with features typical of hemolysis (fever with hemolysis), or attribute hypotension or bleeding in ways not characteristic of FNHTR.