Warm autoimmune hemolytic anemia vs Cold agglutinin disease
How to tell Warm autoimmune hemolytic anemia and Cold agglutinin disease apart when a board question makes them look alike.
Warm AIHA: IgG with a direct Coombs positive for IgG; cold agglutinin disease: IgM with a direct Coombs positive for C3d.
Side by side
IgG-mediated extravascular hemolysis, often with spherocytes and splenic clearance; classic triggers include SLE, CLL, lymphoma, or drugs.
IgM-mediated complement hemolysis worsened by cold exposure, classically after Mycoplasma pneumoniae or EBV infection.
Warm-reactive IgG coats RBCs at body temperature.
Cold-reactive IgM activates complement and agglutinates RBCs.
Direct Coombs positive for IgG supports warm AIHA.
Direct Coombs positive for complement supports cold agglutinin disease.
The trap
Both are Coombs-positive hemolytic anemias, but antibody class and temperature behavior separate them.
Watch it explained
The repair move
For autoimmune hemolysis, identify antibody class, temperature behavior, and trigger pattern.
Try a free question
CoreA patient has hemolytic anemia with spherocytes and a direct Coombs test positive for IgG. Symptoms are not triggered by cold exposure. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Warm autoimmune hemolytic anemia. IgG-mediated extravascular hemolysis at body temperature points to warm AIHA.
Why the other choices are tempting
- B. Cold agglutinin disease is IgM/complement mediated and worsens with cold exposure.
- C. G6PD deficiency causes oxidant-triggered hemolysis with bite cells/Heinz bodies.
- D. Hereditary spherocytosis is Coombs negative.
- E. Sickle cell disease causes vaso-occlusion and sickled RBCs.
Flashcards
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What is the fastest separator for Warm autoimmune hemolytic anemia vs Cold agglutinin disease?
Warm AIHA: IgG with a direct Coombs positive for IgG; cold agglutinin disease: IgM with a direct Coombs positive for C3d.
What clue should make you choose Warm autoimmune hemolytic anemia?
IgG-mediated extravascular hemolysis, often with spherocytes and splenic clearance; classic triggers include SLE, CLL, lymphoma, or drugs.
Quick answers
What is the fastest way to tell Warm autoimmune hemolytic anemia from Cold agglutinin disease?
Warm AIHA: IgG with a direct Coombs positive for IgG; cold agglutinin disease: IgM with a direct Coombs positive for C3d.
What is the key clue for Warm autoimmune hemolytic anemia?
IgG-mediated extravascular hemolysis, often with spherocytes and splenic clearance; classic triggers include SLE, CLL, lymphoma, or drugs.
What is the key clue for Cold agglutinin disease?
IgM-mediated complement hemolysis worsened by cold exposure, classically after Mycoplasma pneumoniae or EBV infection.
What is the common trap with Warm autoimmune hemolytic anemia vs Cold agglutinin disease?
Both are Coombs-positive hemolytic anemias, but antibody class and temperature behavior separate them.