Advanced Clinical Support: Febrile Neutropenia and Tumor Lysis Syndrome

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Febrile Neutropenia: Diagnosis, MASCC Classification, and Antibiotic Therapy

Clinically defined by the presence of a single oral temperature measurement > 38.3 °C or > 38.0 °C sustained for more than 1 hour, combined with an Absolute Neutrophil Count (ANC) < 500/mm³ (or expected to fall below that threshold within the next 48 hours):

ANC = Leucocitos totales (/mm³) × (% Segmented Neutrophils + % Bands)/(100)

1. MASCC Risk Classification: A score ≥ 21 classifies the patient as low risk (eligible for outpatient oral treatment); a score < 21 classifies the patient as high risk (requiring urgent inpatient hospitalization).

2. First-Line Treatment in High Risk: Prioritize starting empiric broad-spectrum intravenous antibiotics with antipseudomonal activity within the first hour of admission, after promptly obtaining paired blood cultures: Piperacillin-Tazobactam (4.5 g IV every 6 hours) o Cefepima o Meropenem.

3. Prophylaxis with Stimulating Factors: For regimens with a febrile neutropenia risk > 20%, prescribe Filgrastim (G-CSF) at 5 µ g/kg/day subcutaneously each day starting the day after chemotherapy, or a single dose of Pegfilgrastim (6 mg SC)..

Tumor Lysis Syndrome (TLS): Cairo-Bishop Criteria and Supportive Care

Occurs secondary to rapid tumor cell lysis following potent chemotherapy in high-burden lymphomas or acute leukemias, with massive dumping of intracellular electrolytes and nucleic acid breakdown products into the systemic circulation:

Tumor Lysis → ↑ Uric Acid, ↑ Potassium, ↑ Phosphorus, and ↓ Calcium

• Cairo-Bishop Laboratory TLS Criteria: At least two of the following changes within 3-7 days of starting chemotherapy: uric acid ≥ 8 mg/dL, potassium ≥ 6 mEq/L, phosphorus ≥ 4.5 mg/dL or calcium ≤ 7 mg/dL.
• Supportive Management: Aggressive intravenous hydration to maintain urine output of 100 mL/m²/hour with close laboratory monitoring.
• Rasburicase Administration: Recombinant urate oxidase converting insoluble uric acid into soluble allantoin, reducing renal burden. Dose: 0.15 - 0.2 mg/kg IV once daily as a 30-minute infusion in established TLS. Absolutely contraindicated in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency because of the risk of severe hemolysis and methemoglobinemia.