A 32-year-old woman with Graves' disease on carbimazole develops fever, severe sore throat, and absolute neutrophil count of 280 cells/µL. What is the most appropriate immediate step?
- A Reduce carbimazole dose and monitor CBC weekly
- B Stop carbimazole immediately, admit, start broad-spectrum antibiotics, use G-CSF if severe ✓
- C Switch to propylthiouracil and continue antithyroid therapy
- D Start propranolol and schedule radioiodine therapy
Explanation
Agranulocytosis (ANC <500 cells/µL) is a rare but life-threatening side effect of thionamides (carbimazole, propylthiouracil) occurring in 0.1–0.5% of patients. Immediate cessation of the offending drug is mandatory — switching to PTU is contraindicated as cross-reactivity for agranulocytosis exists. Patients require hospital admission, blood cultures, broad-spectrum antibiotics, and G-CSF in severe cases. Routine CBC monitoring does not reliably predict or prevent agranulocytosis; patients must be instructed to stop the drug and seek care at any sign of fever or sore throat.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.