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🦋 Thyroid Emergencies — Storm & Myxoedema Coma

Burch-Wartofsky β-block → PTU → Iodine Myxoedema Coma Steroid Cover Clinical Diagnosis
Two Extremes · One Gland Storm · Order Matters Myxoedema · T4/T3 + Steroid ATA thyrotoxicosis guideline · Burch-Wartofsky score · Marino 5th Ed (2025) · Washington Manual
📅 Last reviewed July 2026 · Next review January 2027 · Compiled by Dr. Anmol Srivastava Anaesthesia, Emergency Medicine & Critical Care Medicine · Reviewed by Dr. Tanya Chawla Anaesthesia & Critical Care
📘 1 · Washington Manual of Critical Care

Two Emergencies at Opposite Ends of the Gland

Thyroid emergencies are clinical diagnoses — the hormone levels in thyroid storm are no higher than in uncomplicated thyrotoxicosis, so the diagnosis rests on the picture of decompensation, not on a number. Thyroid storm is thyrotoxicosis with organ failure — hyperpyrexia, tachyarrhythmia, heart failure, agitation or coma, and GI/hepatic dysfunction — almost always tipped over by a precipitant. Myxoedema coma is its mirror image: profound hypothyroidism with hypothermia, hypoventilation, hyponatraemia and depressed consciousness. Both kill if treatment waits for confirmatory tests.

Summarised from the Washington Manual of Critical Care — Thyroid Emergencies.

🔥 Thyroid storm (too much)

  • Hyperpyrexia (often >40 °C), sweating
  • AF / tachyarrhythmia, high-output heart failure
  • Agitation, delirium, seizures, coma
  • Vomiting, diarrhoea, jaundice
  • Precipitant: infection, surgery, iodine/contrast, DKA, childbirth, antithyroid-drug withdrawal

❄️ Myxoedema coma (too little)

  • Hypothermia, bradycardia
  • Hypoventilation → CO₂ retention
  • Hyponatraemia, hypoglycaemia
  • Depressed consciousness, non-pitting oedema
  • Precipitant: infection, cold, sedatives, stopping levothyroxine
📗 2 · Marino's The ICU Book, 5th Edition (2025)

Thyroid Storm — the Sequence Is the Point

The treatment of thyroid storm attacks the disease at every level — release, synthesis, peripheral conversion and end-organ effect — but the order of the drugs matters. A thionamide is given first to stop new hormone synthesis; iodine, which blocks the release of preformed hormone, must be given at least an hour after the thionamide, because giving iodine first supplies fresh substrate to an unblocked gland and can worsen the storm. Beta-blockade controls the catastrophic adrenergic response, and steroid blocks peripheral T4-to-T3 conversion while covering the relative adrenal insufficiency that accompanies the storm.

Summarised from Marino PL. The ICU Book, 5th Ed — Thyroid Storm.
🔬 Thyroid storm — four points of attack, in order
Step 1β-blocker (propranolol) → control adrenergic storm, rate, tremor, and T4→T3 conversion
Step 2Thionamide (propylthiouracil / carbimazole) → block new hormone synthesis
Step 3 — ≥1 h laterIodine (Lugol's / SSKI) → block release of preformed hormone (Wolff-Chaikoff)
Step 4Hydrocortisone → block peripheral T4→T3 conversion + cover adrenal insufficiency
PlusTreat the precipitant (infection), cool actively, and support the failing organs
📗 Marino — why PTU over carbimazole in the storm itself
  • Propylthiouracil (PTU) is preferred acutely because — unlike carbimazole/methimazole — it also blocks peripheral T4→T3 conversion, giving a faster effect on active hormone.
  • Once the storm settles, switch to carbimazole/methimazole for ongoing control (PTU carries a higher risk of hepatotoxicity long-term).
  • Avoid aspirin for the fever — it displaces thyroid hormone from binding proteins and raises free hormone. Use paracetamol and active cooling.
📗 Marino — myxoedema coma is hormone + steroid + support

Give IV levothyroxine (T4) as a loading dose, with liothyronine (T3) added in the sickest patients for a faster onset (balanced against arrhythmia risk). Crucially, give stress-dose hydrocortisone first or alongside — because coexisting adrenal insufficiency is common and thyroid hormone replacement alone can precipitate an adrenal crisis. Then support: passive rewarming, ventilation for CO₂ retention, cautious correction of hyponatraemia and hypoglycaemia, and treat the precipitant.

📋 3 · Storm & Myxoedema — Management

Evidence-Based Management

Diagnose storm clinically — Burch-Wartofsky score ATA
Use the Burch-Wartofsky Point Scale (temperature, CNS effects, GI/hepatic dysfunction, tachycardia, heart failure, atrial fibrillation, precipitant): ≥45 highly suggestive, 25–44 impending, <25 unlikely. It is a clinical scale — do not wait for thyroid function tests to start treatment; send TSH, free T4/T3 but treat on the picture.
Thyroid storm — the ordered regimen STRONG
1. β-blocker — propranolol IV/PO (also blunts T4→T3); use with care in high-output heart failure (short-acting esmolol if unsure). 2. Thionamide — PTU (preferred acutely) or carbimazole. 3. Iodine — Lugol's/SSKI, given ≥1 h after the thionamide. 4. Hydrocortisone 100 mg then 200 mg/day. Plus: active cooling with paracetamol (never aspirin), treat the precipitant, and full supportive care. Cholestyramine can be added to bind enterohepatic hormone in refractory cases; plasma exchange for the truly refractory.
Myxoedema coma — thyroid hormone + steroid + support STRONG
IV levothyroxine (T4) load ~200–400 µg then 50–100 µg/day, ± liothyronine (T3) in the most severe (small doses, arrhythmia risk). Give hydrocortisone 100 mg first/concurrently until adrenal insufficiency is excluded. Support: passive external rewarming (avoid aggressive active rewarming — vasodilatation → shock), ventilate for hypoventilation/CO₂ retention, correct hyponatraemia and hypoglycaemia cautiously, and treat the precipitant (screen hard for infection — the febrile response is blunted).
🇮🇳 Indian Context

India has a large burden of thyroid disease, and thyroid storm is often precipitated by infection, by iodinated contrast, or by non-adherence to antithyroid drugs — a real problem where follow-up and drug supply are inconsistent. Untreated or poorly-controlled Graves' disease and toxic nodular goitre (endemic in some regions) present late. PTU, carbimazole, propranolol, Lugol's iodine and hydrocortisone are all cheap and available — the key is recognising the syndrome and getting the sequence right (thionamide before iodine). For myxoedema coma, IV levothyroxine may be scarce in smaller centres; an oral/NG loading dose of levothyroxine plus IV hydrocortisone and supportive care is a reasonable substitute while arranging transfer.

💊 4 · Drug Doses

Storm & Myxoedema Drug Reference

DrugIndicationDoseNotes
PropranololStorm — adrenergic control (Step 1)60–80 mg PO q4–6h, or 0.5–1 mg IV slowlyAlso blocks T4→T3; esmolol if heart-failure concern
Propylthiouracil (PTU)Storm — synthesis block (Step 2, preferred)500–1000 mg load then 250 mg q4hBlocks peripheral conversion; hepatotoxicity long-term
Carbimazole / methimazoleStorm (alternative) & maintenanceCarbimazole 20 mg q4–6h acutelyPreferred for maintenance once storm settles
Lugol's iodine / SSKIStorm — release block (Step 3)Lugol's ~8 drops q6h / SSKI 5 drops q6hGive ≥1 h AFTER the thionamide
HydrocortisoneStorm & myxoedema (Step 4 / first)100 mg IV then 200 mg/24 hBlocks T4→T3 in storm; covers adrenal insufficiency
Levothyroxine (T4) IVMyxoedema comaLoad ~200–400 µg then 50–100 µg/dayGive hydrocortisone first/with it
Liothyronine (T3) IVSevere myxoedema comaSmall doses (e.g. 5–20 µg) per protocolFaster onset; arrhythmia risk — cautious
🗺 5 · Clinical Flowchart

Recognising & Treating the Thyroid Emergency

1

Recognise the syndrome (clinically)

  • Storm: fever + tachyarrhythmia + CNS/GI failure in a thyrotoxic patient (Burch-Wartofsky ≥45)
  • Myxoedema: hypothermia + hypoventilation + hyponatraemia + ↓consciousness
  • Send TSH/fT4/fT3 & cortisol — but treat on the picture, not the number
2

Storm → the ordered regimen

  • β-blocker → thionamide (PTU) → iodine ≥1 h later → hydrocortisone
  • Cool with paracetamol (never aspirin); treat precipitant; support organs
3

Myxoedema → hormone + steroid + support

  • Hydrocortisone first, then IV levothyroxine (± T3 in the sickest)
  • Passive rewarming, ventilate for CO₂ retention, cautious Na⁺/glucose correction
4

Hunt & treat the precipitant

  • Screen hard for infection (blunted febrile response in myxoedema)
  • Review recent surgery, contrast, DKA, drug non-adherence, sedatives
5

Monitor & transition to definitive care

  • Storm: switch PTU→carbimazole once settled; plan definitive therapy (RAI/surgery)
  • Myxoedema: titrate levothyroxine; endocrinology follow-up; watch for cardiac ischaemia on replacement
⚠️ 6 · Common Mistakes

Common Mistakes in Thyroid Emergencies

❌ Mistake 1 — Giving iodine before the thionamide

Iodine supplied to an unblocked gland provides fresh substrate and can worsen the storm. Always give the thionamide first and iodine at least an hour later.

❌ Mistake 2 — Waiting for thyroid function tests

Hormone levels in storm are no higher than in ordinary thyrotoxicosis. Diagnose and treat on the clinical picture (Burch-Wartofsky), not the lab value.

❌ Mistake 3 — Using aspirin to control the fever

Salicylates displace thyroid hormone from binding proteins and raise free hormone. Use paracetamol and active cooling.

❌ Mistake 4 — Giving thyroid hormone before steroid in myxoedema

Coexisting adrenal insufficiency is common; replacing thyroid hormone first can precipitate an adrenal crisis. Give hydrocortisone first or concurrently.

❌ Mistake 5 — Aggressive active rewarming in myxoedema coma

Rapid rewarming causes peripheral vasodilatation and cardiovascular collapse. Rewarm passively and gradually.

❌ Mistake 6 — Forgetting the precipitant

Both emergencies are usually triggered — most often by infection, which may be occult in myxoedema. Treating the thyroid without the trigger leaves the patient decompensated.

🎓 7 · Exam Pearls — DrNB / PDCC / IFCCM / EDIC

Exam Pearls

Q: What is the drug sequence in thyroid storm?
β-blocker → thionamide (PTU) → iodine (≥1 h after the thionamide) → hydrocortisone, plus treat the precipitant and cool.

Q: Why must iodine follow the thionamide?
Iodine given first supplies substrate to an unblocked gland and can worsen hormone production; the thionamide must block synthesis first.

Q: Why PTU rather than carbimazole in the storm?
PTU additionally blocks peripheral T4→T3 conversion; switch to carbimazole for maintenance once settled.

Q: How is thyroid storm diagnosed?
Clinically, with the Burch-Wartofsky score (≥45 highly suggestive) — hormone levels don't distinguish it from simple thyrotoxicosis.

Q: What is the treatment of myxoedema coma?
IV levothyroxine (± T3), with hydrocortisone given first/concurrently, passive rewarming, ventilatory support, and cautious Na⁺/glucose correction.

Q: Why give steroid before thyroxine in myxoedema coma?
Coexisting adrenal insufficiency is common; thyroid hormone alone can precipitate adrenal crisis.

Q: Which antipyretic is contraindicated in storm?
Aspirin — it displaces thyroid hormone from binding proteins and increases the free fraction.

📚 8 · References

References

  1. Ross DS, Burch HB, Cooper DS, et al. (ATA). 2016 American Thyroid Association Guidelines for Diagnosis and Management of Hyperthyroidism and Thyrotoxicosis. Thyroid. 2016;26:1343–1421.
  2. Burch HB, Wartofsky L. Life-threatening thyrotoxicosis: thyroid storm. Endocrinol Metab Clin North Am. 1993;22:263–277.
  3. Wartofsky L. Myxedema Coma. Endocrinol Metab Clin North Am. 2006;35:687–698.
  4. Klubo-Gwiezdzinska J, Wartofsky L. Thyroid emergencies. Med Clin North Am. 2012;96:385–403.
  5. Marino PL. The ICU Book, 5th Edition. Thyroid Dysfunction in Critical Illness. Wolters Kluwer; 2025.
  6. Washington Manual of Critical Care, 4th Edition. Kollef MH, Witt CA (eds). Thyroid Emergencies. Wolters Kluwer; 2023.