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EMERGENCY

Thyroid Storm

High EvidenceUpdated: 2025-12-24

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Red Flags

  • Hyperpyrexia (> 39-40°C)
  • Unexplained Delirium/Coma
  • Jaundice + Heart Failure (Impending Death)
Overview

Thyroid Storm

1. Clinical Overview

Summary

Thyroid Storm (Thyrotoxic Crisis) is a rare, life-threatening emergency characterized by severe decompensation of thyrotoxicosis. It represents an extreme metabolic state driven by excess thyroid hormone action. The mortality rate is high (10-30%) even with treatment. Diagnosis is clinical, often supported by the Burch-Wartofsky Point Scale. It usually occurs in patients with undiagnosed or poorly controlled Graves' disease who encounter a precipitating stressor. [1,2]

Key Facts

  • The "Storm": It is not defined by T4 levels (which correlate poorly with severity) but by End-Organ Damage:
    • CNS: Agitation, Delirium, Coma.
    • CVS: Tachycardia (>140bpm), Atrial Fibrillation, High Output Heart Failure.
    • GI: Vomiting, Diarrhoea, Jaundice covers hepatic dysfunction.
    • Thermoregulation: Fever is almost universal (>38.5°C).

Clinical Pearls

The "One Hour Rule": When treating, administer the Antithyroid Drug (PTU/Carbimazole) at least 1 hour BEFORE giving Iodine. If you give Iodine first, the active gland will use it to synthesize more hormone (the Jod-Basedow effect). By blocking synthesis first, the Iodine then acts to block release (the Wolff-Chaikoff effect).

Apathetic Storm: In the elderly, classic signs may be absent. They present with "Apathetic Thyrotoxicosis": lethargy, severe weight loss, and unexplained heart failure/AF, without the fever or agitation.

Propranolol: The beta-blocker of choice. It has a dual mechanism: 1) Blocks beta-adrenergic receptors (lowers HR), and 2) Inhibits peripheral conversion of T4 to T3 (the active hormone).

2. Epidemiology

Incidence

  • Rare: 1-2% of hospital admissions for thyrotoxicosis.
  • Gender: F > M (associated with Graves').

Triggers (Precipitants)

  • Infection (Most common).
  • Surgery (Thyroidectomy or non-thyroidal).
  • Trauma.
  • Withdrawal of antithyroid medication.
  • Iodine Load (CT Contrast, Amiodarone).
  • Diabetic Ketoacidosis.
  • Parturition (Childbirth).
3. Pathophysiology

Mechanisms

The exact mechanism is unknown, but theories include:

  1. Rapid Increase: Sudden dump of hormone (e.g. surgical manipulation).
  2. Increased Sensitivity: Upregulation of catecholamine receptors makes tissues hypersensitive to adrenaline.
  3. Decreased Binding: Systemic illness reduces TBG, increasing free T4/T3 fractions.
4. Clinical Presentation

Burch-Wartofsky Criteria

A score > 45 is highly suggestive of Storm.

  1. Temperature: 37.2–37.7 (5pts) ... >40.0 (30pts).
  2. CNS Effects: Mild Agitation (10pts) ... Coma (30pts).
  3. GI Dysfunction: Diarrhoea (10pts) ... Jaundice (20pts).
  4. Tachycardia: 99–109 (5pts) ... >140 (25pts).
  5. Heart Failure: Mild oedema (5pts) ... Pulmonary Oedema (15pts).
  6. Atrial Fibrillation: Present (10pts).
  7. Precipitant History: Positive (10pts).
5. Clinical Examination
  • General: Profusely sweating, flushed, restless, shaking.
  • Neck: Goitre (may have bruit).
  • Eyes: Lid lag, Exophthalmos (Graves').
  • Chest: Fast AF, Crackles (failure).
6. Investigations

Endocrine

  • TSH: Suppressed (less than 0.01).
  • Free T4 / T3: Significantly elevated.
  • Cortisol: Check to rule out co-existing Addison's (Polyglandular syndrome).

General

  • FBC: Leukocytosis (infection or stress).
  • LFTs: Abnormal (hepatic dysfunction is part of the storm).
  • Calcium: Hypercalcaemia (increased bone turnover).
  • ECG: Sinus Tachycardia or AF.
7. Management

Management Algorithm

           SUSPECTED THYROID STORM
      (Fever + Tachycardia + CNS changes)
                    ↓
          ABCDE RESUSCITATION
    - High flow oxygen
    - IV Fluids (Dextrose-Saline)
    - Active Cooling (Ice packs/Paracetamol)
    - WARNING: Do NOT use Aspirin (displaces T4)
                    ↓
          1. BETA BLOCKADE
    - Propranolol 40-80mg PO q4h
    - Or IV Esmolol (titratable)
                    ↓
          2. BLOCK SYNTHESIS (Thionamide)
    - Propylthiouracil (PTU) 600-1000mg Loading
      (Preferred: Blocks T4->T3)
    - Or Carbimazole 60-100mg
                    ↓
          3. BLOCK RELEASE (Iodine)
    - **WAIT 1 HOUR AFTER PTU**
    - Lugol's Iodine or Potassium Iodide
    - Or Lithium (if iodine allergic)
                    ↓
          4. BLOCK CONVERSION (Steroids)
    - Hydrocortisone 100mg IV q6h
    - Or Dexamethasone 4mg IV q6h
                    ↓
          5. DEFINITIVE CARE
    - Treat precipitant (Antibiotics?)
    - Plasmapheresis (if refractory)
    - Thyroidectomy (once stable)

1. Supportive Measures

  • Cooling: Paracetamol, cooling blankets.
  • Avoid Aspirin: It displaces T4 from binding proteins, increasing free hormone levels.
  • Sedation: Benzodiazepines for severe agitation.

2. Specific Drug Rationale

  • PTU vs Carbimazole: PTU is preferred in storm (and 1st trimester pregnancy) because it blocks peripheral conversion of T4 to T3. Carbimazole does not.
  • Steroids: Vital. They block T4->T3 conversion and treat potential relative adrenal insufficiency (which mimics storm: shock/fever).
  • Cholestyramine: Can be used to sequester thyroid hormone in the gut (blocks enterohepatic recycling).
8. Complications
  • Cardiovascular: High output cardiac failure, Arrhythmias, Embolism.
  • Neurological: Coma, Seizures.
  • Hepatic: Failure (from storm or PTU).
9. Prognosis and Outcomes
  • Mortality: 10-30% despite treatment.
  • Recovery: Clinical improvement usually seen within 12-24 hours. Full resolution of crisis takes days.
10. Evidence and Guidelines

Key Guidelines

GuidelineOrganisationKey Recommendations
Thyrotoxicosis MgmtAmerican Thyroid Assoc. (2016)Multimodality treatment algorithm. PTU preference.
Endocrine EmergenciesSociety for EndocrinologyCritical care admission mandatory.

Diagnostic Evidence

Burch-Wartofsky vs Akamizu:

  • Burch-Wartofsky is highly sensitive but non-specific (can over-diagnose).
  • Akamizu (JTA) criteria are more strict (require specific combinations of symptoms).
  • In emergency settings, BW is preferred to avoid missing cases.
11. Patient and Layperson Explanation

What is a Thyroid Storm?

It is a rare and dangerous condition where the thyroid gland releases massive amounts of hormone suddenly, sending the body into overdrive.

What are the symptoms?

The body's metabolism runs out of control. The patient develops a very high fever, a racing heart rate (often irregular), profuse sweating, and becomes confused or delirious.

What causes it?

It usually happens in someone who already has an overactive thyroid (Graves' disease) but hasn't been treated or has stopped their medication. A trigger, like a severe infection or surgery, then tips them over the edge.

How is it treated?

It is an intensive care emergency. We use:

  1. Drugs to slow the heart.
  2. Drugs to stop the thyroid making new hormone.
  3. Iodine (later) to lock the hormone inside the gland.
  4. Steroids to calm the inflammation.
12. References

Primary Sources

  1. Ross DS, et al. 2016 American Thyroid Association Guidelines for Diagnosis and Management of Hyperthyroidism and Other Causes of Thyrotoxicosis. Thyroid. 2016.
  2. Burch HB, Wartofsky L. Life-threatening thyrotoxicosis. Thyroid storm. Endocrinol Metab Clin North Am. 1993.
  3. NICE CKS. Hyperthyroidism - Management.
13. Examination Focus

Common Exam Questions

  1. Management: "Order of drugs?"
    • Answer: Antithyroid (PTU) -> Wait 1h -> Iodine.
  2. Pharmacology: "Why PTU over Carbimazole?"
    • Answer: PTU blocks peripheral T4->T3 conversion.
  3. Contraindication: "Which antipyretic to avoid?"
    • Answer: Aspirin (displaces T4).
  4. Score: "Diagnostic scale?"
    • Answer: Burch-Wartofsky.

Viva Points

  • Wolff-Chaikoff Effect: Explain it. High levels of iodide acutely inhibit thyroid hormone synthesis/release. This is temporary (the "escape phenomenon occurs after 10 days"), so it is used for Storm or Pre-op prep, not long term.
  • Apathetic Hyperthyroidism: Why is it called apathetic? Because the elderly patient appears withdrawn/depressed rather than hyperactive.

Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.

Last updated: 2025-12-24

At a Glance

EvidenceHigh
Last Updated2025-12-24
Emergency Protocol

Red Flags

  • Hyperpyrexia (> 39-40°C)
  • Unexplained Delirium/Coma
  • Jaundice + Heart Failure (Impending Death)

Clinical Pearls

  • **Propranolol**: The beta-blocker of choice. It has a dual mechanism: 1) Blocks beta-adrenergic receptors (lowers HR), and 2) Inhibits peripheral conversion of T4 to T3 (the active hormone).
  • M (associated with Graves').
  • T3 conversion and treat potential relative adrenal insufficiency (which mimics storm: shock/fever).

Guidelines

  • NICE Guidelines
  • BTS Guidelines
  • RCUK Guidelines