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Carbimazole Agranulocytosis — RACP Adult Medicine MCQ

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HardEndocrinologyCarbimazole AgranulocytosisRACP Adult Medicine

A 50-year-old taking carbimazole for Graves disease presents with fever, oral ulcers and an absolute neutrophil count of 0.1 x 10^9/L. What is the immediate management priority?

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Correct answer: B — Stop carbimazole permanently, obtain cultures and commence urgent empiric treatment for neutropenic sepsis

The best answer is “Stop carbimazole permanently, obtain cultures and commence urgent empiric treatment for neutropenic sepsis”. Fever with profound neutropenia during thionamide treatment is presumed agranulocytosis: the drug is stopped and neutropenic sepsis is treated immediately after cultures are obtained. Dose reduction or delayed review is unsafe. Another thionamide is not a routine substitute because cross-reactivity can occur; definitive thyroid treatment is planned after recovery. Growth-factor use is a haematology decision and does not replace antibiotics.

Reference: Queensland Health: Hyperthyroidism clinical prioritisation criteria: https://www.health.qld.gov.au/cpc/diabetes-and-endocrinology/hyperthyroidism