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Thyroid disease and anaesthetic physiology — FRCA Primary MCQ

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ModeratePhysiologyThyroid disease and anaesthetic physiologyFRCA Primary

A patient with untreated thyrotoxicosis develops tachycardia and pyrexia during emergency surgery. Which physiological change is most relevant to the increased peri-operative risk?

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Correct answer: E — Increased basal metabolic rate and adrenergic sensitivity

Thyrotoxicosis increases basal metabolic rate, oxygen consumption and adrenergic responsiveness, predisposing to tachyarrhythmia and hyperthermia. Reduced oxygen consumption and reduced β-responsiveness are the opposite of the expected physiology. Functional residual capacity is not the key issue. Recognising thyroid storm matters because treatment includes β-blockade, antithyroid therapy and supportive care.

Reference: Ganong Review of Medical Physiology; Primary FRCA physiology texts