Management of Severe Neutropenia and Leukocytosis

Evaluation and Management

The management of leukocytosis with increased Absolute Neutrophil Count (ANC) should be tailored to the underlying cause, with immediate intervention required for severe neutropenia (ANC <500/mm³) to prevent life-threatening infections, according to the American College of Physicians 1
For patients with mild to moderate leukocytosis (ANC >1500/mm³), monitoring of complete blood counts is recommended regularly until resolution, as suggested by the American Society of Hematology 2
Initiation of G-CSF (filgrastim) at 5 mcg/kg/day subcutaneously is recommended until ANC recovers to >1000/mm³ in cases of severe neutropenia, as per the National Comprehensive Cancer Network 1

For imatinib-induced neutropenia (ANC <1000/mm³), the drug should be held until ANC ≥1500/mm³ and resumed at the starting dose, with reduction to 300 mg if recurrence occurs, as recommended by the National Comprehensive Cancer Network 3, 1
For dasatinib-induced neutropenia (ANC <0.5 × 10⁹/l), the drug should be held until ANC ≥1.0 × 10⁹/l and platelets ≥20 × 10⁹/l, and resumed at the original starting dose, with reduction if recurrence occurs, as suggested by the European Society for Medical Oncology 4

Weekly CBC monitoring is recommended for the first 4-6 weeks for patients on chemotherapy or TKIs, with frequency adjusted based on stability, as advised by the American Society of Clinical Oncology 1
Referral to hematology is recommended for extremely elevated white blood cell counts (>50,000/mm³), concurrent abnormalities in red blood cell or platelet counts, or presence of immature white blood cells or blasts on peripheral smear, as suggested by the American Society of Hematology 5, 6