Hematology Oncology · Year 2 · from Hematology Oncology

Case 2: Warm Autoimmune Hemolytic Anemia

Patient Presentation

Demographics: 42-year-old female

Chief Complaint: Sudden onset of fatigue, jaundice, and dark urine for 5 days

History of Present Illness: The patient was in her usual state of health until 1 week ago when she developed an upper respiratory infection. She then noticed progressive fatigue, yellowing of her eyes, and dark "cola-colored" urine. She denies any new medications, recent travel, or family history of anemia or jaundice.

Physical Examination:

  • Vital signs: BP 110/65, HR 108, RR 20, Temp 37.4C
  • General: Pale, icteric woman in mild distress
  • HEENT: Scleral icterus, conjunctival pallor
  • Cardiac: Tachycardic, III/VI systolic flow murmur
  • Abdomen: Splenomegaly (3 cm below costal margin), no hepatomegaly
  • Skin: Jaundice, no petechiae or rashes

Workup and Results

Complete Blood Count:

  • WBC: 12,400/uL (elevated)
  • Hemoglobin: 6.8 g/dL (severely low, was 13.2 g/dL 6 months ago)
  • MCV: 105 fL (elevated due to reticulocytosis)
  • Platelets: 235,000/uL (normal)
  • Reticulocyte count: 14% (markedly elevated)
  • Absolute reticulocyte count: 420,000/uL

Hemolysis Labs:

  • LDH: 680 U/L (elevated)
  • Total bilirubin: 5.2 mg/dL (elevated)
  • Indirect bilirubin: 4.6 mg/dL (elevated)
  • Haptoglobin: < 10 mg/dL (undetectable)
  • Urinalysis: Urobilinogen elevated, no hemoglobinuria

Peripheral Blood Smear:

  • Polychromasia (reticulocytes)
  • Spherocytes present
  • No schistocytes or sickle cells
  • Nucleated RBCs present

Direct Antiglobulin Test (Coombs):

  • DAT: Positive
  • Monospecific: IgG positive, C3 negative

ANA: Weakly positive (1:80)

Diagnosis

Warm Autoimmune Hemolytic Anemia (AIHA)

Key diagnostic features:

  • Evidence of hemolysis: elevated LDH, indirect bilirubin, undetectable haptoglobin
  • Elevated reticulocyte count (appropriate marrow response)
  • Positive DAT with IgG (characteristic of warm AIHA)
  • Spherocytes on smear (from partial phagocytosis)
  • Extravascular hemolysis pattern (splenomegaly, no hemoglobinuria)

Treatment Plan

  1. First-line therapy:
  • Prednisone 1 mg/kg/day (60-80 mg daily)
  • Folic acid 1 mg daily
  • Monitor hemoglobin every 2-3 days initially
  1. Transfusion if needed:
  • Transfuse for symptomatic anemia or hemoglobin < 7 g/dL with symptoms
  • Blood may be "least incompatible" - transfuse anyway if clinically needed
  1. If steroid-refractory (no response by 3 weeks):
  • Rituximab (anti-CD20)
  • Consider splenectomy for refractory cases
  1. Workup for secondary causes:
  • Evaluate for underlying lymphoproliferative disorder
  • Complete autoimmune workup (lupus panel)

Teaching Points

  1. Warm AIHA involves IgG antibodies that opsonize RBCs for splenic destruction
  2. The DAT (direct Coombs test) is positive for IgG +/- C3
  3. Spherocytes form when splenic macrophages remove portions of antibody-coated membrane
  4. The MCV may be elevated due to reticulocytosis (reticulocytes are larger than mature RBCs)
  5. Undetectable haptoglobin is the most sensitive marker for hemolysis
  6. Always look for underlying causes: lymphoma, CLL, lupus, drugs
  7. Transfusion should not be withheld for life-threatening anemia despite difficulty crossmatching

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