Hematology, Oncology, and Immunology
Sickle cell disease and anemia
Penicillin prophylaxis until age 5 reduces invasive pneumococcal disease; add folic acid and hydroxyurea for frequent crises. Acute chest syndrome and vaso-occlusive crises need aggressive analgesia, hydration, and oxygen. Iron deficiency anemia: elemental iron 3–6 mg/kg/day divided once or twice daily; reticulocytosis appears in 1–2 weeks, and hemoglobin normalizes over 4–8 weeks. Give on an empty stomach, avoid coadministration with milk or calcium, and continue 2–3 months after normalization to replenish stores. In G6PD deficiency, avoid dapsone, nitrofurantoin, primaquine, sulfonamides, and methylene blue.
Chemotherapy principles
Antiemetic prophylaxis usually combines a 5-HT3 antagonist, dexamethasone, and aprepitant for highly emetogenic regimens. Methotrexate requires leucovorin rescue and careful hydration and urine alkalinization at high doses. Doxorubicin causes cumulative cardiotoxicity that dexrazoxane can mitigate. Vincristine is fatal if given intrathecally - never remove it from its designated packaging for intrathecal use. Cisplatin causes nephrotoxicity and ototoxicity; ifosfamide causes hemorrhagic cystitis, prevented with mesna and hydration.
Tumor lysis and febrile neutropenia
Tumor lysis syndrome: hyperuricemia, hyperkalemia, hyperphosphatemia, and hypocalcemia; treat with aggressive hydration and allopurinol or rasburicase. Rasburicase is contraindicated in G6PD deficiency because of hemolysis risk. Febrile neutropenia requires empiric broad-spectrum coverage such as cefepime within 60 minutes.
Worked example
A 20 kg child with iron deficiency anemia: 3 mg/kg/day elemental iron = 60 mg elemental iron daily. Ferrous sulfate is 20% elemental iron, so 300 mg of ferrous sulfate supplies 60 mg. Recheck hemoglobin and reticulocyte count in 2–4 weeks to confirm response.