Management of Agranulocytosis in Patients Taking Antithyroid Drugs

Immediate Recognition and Diagnosis

The American Heart Association recommends immediate discontinuation of the antithyroid drug and initiation of broad-spectrum intravenous antibiotics and granulocyte colony-stimulating factor (G-CSF) as soon as agranulocytosis is confirmed to shorten recovery time 1
Agranulocytosis is defined as absolute neutrophil count (ANC) <500/mm³ in the presence of antithyroid drugs, with an incidence of approximately 0.1-1% of patients treated with thionamide drugs 1

The American Academy of Child and Adolescent Psychiatry suggests that discontinuing the antithyroid drug immediately upon confirmation is the single most critical intervention, as agranulocytosis is usually reversible once the drug is stopped 1
Administering recombinant human granulocyte colony-stimulating factor (G-CSF) at 300 mcg/day intravenously can accelerate neutrophil recovery 1

If ANC <1,000/mm³, stop the antithyroid drug immediately and monitor the patient for infection with daily blood cell counts 3

Patient education about symptoms is more cost-effective than routine monitoring, as agranulocytosis onset is typically acute and symptomatic, and patients should be warned to seek immediate medical attention if they develop fever, sore throat, or flu-like symptoms, especially within the first 3 months of treatment 2
Weekly complete blood counts during the first 3 months of therapy are recommended to detect early agranulocytosis 1