“7 Key Insights Into Autoimmune Hemolytic Anemia: Diagnosis & Management”

Introduction
Autoimmune Hemolytic Anemia (AIHA) is a rare yet life-threatening condition caused by the immune system attacking red blood cells. Understanding its etiology, pathogenesis, and diagnostic approach is critical for effective management.

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Etiology of Autoimmune Hemolytic Anemia

1. Primary Causes

• Idiopathic: 50% of AIHA cases are idiopathic.

1. Secondary Causes

• Autoimmune Disorders: Systemic lupus erythematosus (SLE)
• Infections: Mycoplasma pneumoniae, Epstein-Barr virus
• Drugs: Methyldopa, penicillin
• Malignancies: Chronic lymphocytic leukemia

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Pathogenesis of AIHA

AIHA involves immune-mediated destruction of red blood cells (RBCs). The two main types are:

• Warm AIHA: IgG antibodies attach to RBCs at body temperature, leading to phagocytosis in the spleen.
• Cold AIHA: IgM antibodies bind to RBCs at low temperatures, activating complement-mediated lysis.

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Diagnostic Workup of AIHA

• Clinical Features
• Fatigue, pallor, and jaundice
• Splenomegaly
• Laboratory Tests

1. Complete Blood Count: Anemia with reticulocytosis
2. Peripheral Blood Smear: Spherocytes and agglutination
3. Direct Antiglobulin Test (DAT): Confirms presence of autoantibodies
4. LDH and Bilirubin: Elevated due to hemolysis

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Management of Autoimmune Hemolytic Anemia

1. First-line Therapy

• Corticosteroids: Prednisone 1–2 mg/kg/day

1. Second-line Therapy

• Rituximab or splenectomy for refractory cases

1. Supportive Care

• Blood transfusions (cross-match compatible)
• Folate supplementation

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Clinical Scenario-Based MCQs on Autoimmune Hemolytic Anemia

Question 1
A 25-year-old woman presents with fatigue, jaundice, and dark-colored urine. Physical examination reveals pallor and mild splenomegaly. Laboratory findings include hemoglobin of 8 g/dL, reticulocyte count of 8%, elevated indirect bilirubin, and a positive direct antiglobulin test (DAT). What is the most likely diagnosis?
A. Iron deficiency anemia
B. Warm autoimmune hemolytic anemia
C. Cold agglutinin disease
D. Paroxysmal nocturnal hemoglobinuria

Answer: B. Warm autoimmune hemolytic anemia
Explanation: The clinical presentation of fatigue, jaundice, splenomegaly, and dark urine, along with a positive DAT, strongly suggests warm AIHA. The elevated reticulocyte count and bilirubin indicate hemolysis.

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Question 2
A 6-year-old BOY reports cyanosis in his fingertips during exposure to cold weather. Laboratory tests reveal anemia with agglutinated red cells on a peripheral smear and a positive cold agglutinin titer. Which of the following is the most appropriate next step in management?
A. Warm blankets and avoid cold exposure
B. High-dose corticosteroids
C. Blood transfusion with warmed blood
D. Plasmapheresis

Answer: A. Warm blankets and avoid cold exposure
Explanation: In cold agglutinin disease, management involves avoiding cold temperatures to prevent hemolysis. Corticosteroids are not effective in cold AIHA, and plasmapheresis is reserved for severe cases.

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Question 3
A patient with autoimmune hemolytic anemia is started on prednisone but shows no improvement after four weeks. Which of the following is the most appropriate second-line treatment?
A. Intravenous immunoglobulin
B. Rituximab
C. Folic acid supplementation
D. Hydroxyurea

Answer: B. Rituximab
Explanation: Rituximab is the preferred second-line therapy for refractory AIHA. Folic acid supplementation supports erythropoiesis but is not a definitive treatment for AIHA.

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Question 4
A 35-year-old patient with lupus presents with fatigue and jaundice. Laboratory findings confirm warm AIHA. Which test result is most consistent with this condition?
A. Positive Coombs test
B. Low reticulocyte count
C. Normal LDH levels
D. Low serum bilirubin

Answer: A. Positive Coombs test
Explanation: The direct Coombs test (DAT) detects autoantibodies on RBCs and is a hallmark of warm AIHA. Hemolysis typically leads to elevated reticulocyte count, LDH, and bilirubin.

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Question 5
What is the main mechanism behind the hemolysis in warm autoimmune hemolytic anemia?
A. Complement activation and intravascular destruction
B. IgG-mediated opsonization and splenic destruction
C. Direct RBC lysis by T cells
D. Microangiopathic mechanical damage

Answer: B. IgG-mediated opsonization and splenic destruction
Explanation: In warm AIHA, IgG autoantibodies bind to RBCs at body temperature, leading to phagocytosis and destruction in the spleen.