How is a leukemoid reaction managed and treated?

Management and Treatment of Leukemoid Reaction

The management of leukemoid reaction focuses on treating the underlying cause while providing supportive care, with aggressive hydration being a cornerstone of initial management. 1

Definition and Etiology

• Leukemoid reaction is defined as persistent neutrophilic leukocytosis above 50,000 cells/μL when the cause is other than leukemia 2
• Common causes include:
  • Severe infections (59% of cases) 3
  • Malignancies (both hematologic and non-hematologic) 2, 4
  • Severe hemorrhage or acute hemolysis 2
  • Metabolic disorders such as diabetic ketoacidosis 5

Diagnostic Approach

• Differential diagnosis must exclude chronic myelogenous leukemia (CML) and chronic neutrophilic leukemia (CNL) 2
• Diagnostic workup includes:
  • Complete blood count with peripheral smear examination 3
  • Flow cytometry to rule out leukemia 4
  • Identification of underlying cause through appropriate investigations 2

Treatment Algorithm

1. Initial Management

• Aggressive hydration is the first-line intervention for all patients with leukemoid reaction 1
  • Intravenous hydration at 2.5-3 liters/m²/day is recommended, particularly in patients with hyperleukocytosis 1
  • Rehydration alone may help normalize white blood cell counts in dehydration-induced cases 1

2. Management of Hyperleukocytosis

• For WBC counts >100,000/μL with symptoms of leukostasis (e.g., pulmonary infiltrates, retinal or cerebral hemorrhages):
  • Immediate medical treatment is required 6
  • Consider hydroxyurea at dosages up to 50-60 mg/kg per day until WBC decreases to <10-20 × 10⁹/L 6
  • Leukapheresis may be considered for initial management, though its impact on long-term outcomes is not established 6

3. Prevention of Complications

• Monitor for and prevent tumor lysis syndrome in cases of malignancy-associated leukemoid reaction:
  • Ensure adequate hydration 6
  • Control uric acid production using allopurinol or rasburicase 6
  • Monitor urine pH 6
• Avoid excessive red blood cell transfusions until WBC has been reduced, as this can increase blood viscosity 6

4. Specific Treatment Based on Etiology

• Infections: Appropriate antimicrobial therapy based on identified pathogen 3
• Malignancies: Treatment of the underlying cancer 4
• Metabolic disorders: Correction of metabolic abnormalities (e.g., hyperglycemia and electrolyte imbalances in diabetic ketoacidosis) 5

Supportive Care

• Transfusion support may be required:
  • Maintain hemoglobin above 8 g/dL 6
  • Platelet transfusions if count falls below 10 × 10⁹/L or if there is active bleeding 6
• For severe inflammatory responses, corticosteroids may be considered, with careful attention to benefit-risk ratio 7

Monitoring and Prognosis

• Regular monitoring of complete blood count is essential to assess response to treatment 3
• Prognosis depends on the underlying cause, with infection and paraneoplastic leukemoid reactions associated with high mortality 3
• Risk factors for poor outcomes include:
  • Lower hemoglobin levels 3
  • Older age 3
  • Increased segmented neutrophil count 3

Special Considerations

• In pediatric patients, particularly preterm infants, consider congenital infections such as cytomegalovirus as potential causes 8
• In pregnant patients with leukemoid reaction, management should be coordinated between hematologists, obstetricians, and neonatologists 6