FFinalistSouthampton · 2027
Acute care
AKT · Acute care/Metabolic & endocrinelow yield

Thyroid storm & myxoedema coma

Decompensated extreme hyper-/hypothyroidism

Overview

The two endocrine extremes: thyroid storm (life-threatening thyrotoxicosis — fever, tachyarrhythmia, agitation) and myxoedema coma (decompensated hypothyroidism — hypothermia, bradycardia, reduced consciousness). Both are precipitated by illness/surgery and are clinical emergencies.

Recognise

  • Thyroid storm: high fever, AF/tachycardia, agitation/delirium, vomiting, heart failure
  • Myxoedema coma: hypothermia, bradycardia, hypoventilation, hyponatraemia, reduced GCS
  • Both: a precipitant (infection, surgery, treatment changes)

Red flags

  • Storm: hyperthermia + cardiovascular collapse/arrhythmia. Myxoedema: hypothermia + CO2 retention + coma

Differentials & how to tell them apart

Sepsisshares fever/tachycardia (storm) or hypothermia (myxoedema) — often the precipitant; treat both
Anticholinergic/sympathomimetic toxidromedrug history, no thyroid derangement
Other causes of reduced GCSglucose, CO2, drugs — myxoedema is part of the coma differential

Investigations

TFTs, but treat clinically; FBC/CRP/cultures (precipitant), glucose, U&E (Na+), cortisol (coexisting adrenal insufficiency), ECG.

Management

Storm: beta-blocker + antithyroid + iodine + hydrocortisone · Myxoedema: IV thyroid hormone + hydrocortisone + rewarm

  1. 1Storm: propranolol, antithyroid drug (PTU/carbimazole), then iodine (after the antithyroid), hydrocortisone, cooling, treat precipitant. Myxoedema: cautious IV thyroid hormone, IV hydrocortisone, gentle rewarming, ventilatory support.Gate: Give hydrocortisone (cover possible adrenal insufficiency) and, in storm, give iodine only AFTER the antithyroid drug (iodine first would fuel hormone synthesis)
  2. 2Critical care; identify/treat the precipitant; correct electrolytes/glucose; definitive thyroid management later.
Storm: propranolol + propylthiouracil/carbimazole + iodine (after antithyroid) + hydrocortisone — beta-blockade, block synthesis then release; steroids
Myxoedema: IV levothyroxine/liothyronine + IV hydrocortisone + rewarming — give steroids before/with thyroid hormone

Key points

In storm, the order matters: beta-block, block synthesis (PTU/carbimazole), THEN block release (iodine). Both crises need steroid cover.

Monitor & prognosis

Temperature, cardiac rhythm, GCS, electrolytes, response.

High mortality if unrecognised; good with prompt treatment.

Source: Society for Endocrinology; BNF