Hematology Oncology · Year 2 · from Hematology Oncology

Case 3: Reticulocytosis - Appropriate Marrow Response

Patient Presentation

Demographics: 32-year-old female

Chief Complaint: Fatigue and dark urine for 5 days

History of Present Illness: The patient was in her usual state of health until 5 days ago when she developed progressive fatigue, mild jaundice noted by family, and dark "cola-colored" urine. She had a viral upper respiratory infection 2 weeks ago that has since resolved. She denies any new medications, toxin exposure, or family history of anemia.

Physical Examination:

  • Vital signs: BP 115/75, HR 102, RR 18, Temp 37.0C
  • General: Mild pallor and icterus
  • HEENT: Scleral icterus, conjunctival pallor
  • Cardiac: Tachycardic, II/VI systolic flow murmur
  • Abdomen: Mild splenomegaly (2 cm below costal margin)
  • Skin: No rash or petechiae

Workup and Results

Complete Blood Count:

  • WBC: 9,200/uL (normal)
  • Hemoglobin: 8.4 g/dL (decreased from baseline 13.5)
  • MCV: 108 fL (elevated)
  • Platelets: 225,000/uL
  • Reticulocyte count: 12% (markedly elevated)
  • Absolute reticulocyte count: 350,000/uL

Hemolysis Labs:

  • LDH: 520 U/L (elevated)
  • Indirect bilirubin: 3.8 mg/dL (elevated)
  • Haptoglobin: <10 mg/dL (undetectable)
  • Direct antiglobulin test (DAT): Positive (IgG only)

Peripheral Blood Smear:

  • Polychromasia (reticulocytes)
  • Spherocytes present
  • No schistocytes

Clinical Image

Peripheral blood smear showing polychromasia (bluish-purple cells) representing reticulocytes, indicating active bone marrow erythropoietic response. Image source: Wikimedia Commons. License: CC BY-SA 3.0

Diagnosis

Warm Autoimmune Hemolytic Anemia (AIHA)

Supporting evidence:

  • Positive DAT (IgG) confirming immune-mediated hemolysis
  • Spherocytes from partial phagocytosis of antibody-coated RBCs
  • Elevated reticulocyte count indicating appropriate marrow response
  • Macrocytosis from reticulocytosis (reticulocytes are larger than mature RBCs)

Treatment Plan

  1. First-line therapy:
  • Prednisone 1 mg/kg/day
  • Folic acid supplementation
  1. Monitoring:
  • Follow hemoglobin and reticulocyte count for response
  • Expect improvement within 1-2 weeks
  1. If refractory:
  • Rituximab
  • Splenectomy consideration

Teaching Points

  1. Reticulocyte count is the key indicator of bone marrow erythropoietic response
  2. Elevated reticulocytes indicate the marrow is responding appropriately to anemia (peripheral destruction or blood loss)
  3. Low reticulocytes in anemia indicate a production problem (hypoproliferative anemia)
  4. Reticulocytes appear as polychromatic (bluish) cells on Wright-stained smear due to residual RNA
  5. The reticulocyte production index corrects for both anemia severity and early release
  6. MCV may be elevated due to reticulocytosis since reticulocytes are larger than mature RBCs

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