Hyperthyroid Crisis (thyroid storm)

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management

Definition

Hyperthyroid crisis (thyroid storm) is a life threatening exacerbation of hyperthyroidism, characterised by severe metabolic instability and multi organ dysfunction.

Aetiology

  • Precipitating factors: infection, surgery, trauma, pregnancy, iodine load (e.g., contrast media, amiodarone), abrupt cessation of antithyroid medication.
  • Underlying hyperthyroidism: Graves’ disease (most common), toxic multinodular goitre, toxic adenoma.

Pathophysiology

  • Excess thyroid hormones increase metabolic rate, leading to a hyperadrenergic state.
  • Increased catecholamine sensitivity results in cardiovascular, neurological, and thermoregulatory instability.
  • Severe hyperthermia, tachycardia, and multi-organ failure can occur if untreated.

Risk Factors

  • Uncontrolled or undertreated hyperthyroidism.
  • Recent surgery or trauma.
  • Acute infections.
  • Iodine containing contrast exposure.
  • Pregnancy or childbirth.

Signs and Symptoms

  • Neurological: agitation, delirium, seizures, coma.
  • Cardiovascular: tachycardia, atrial fibrillation, heart failure, hypotension.
  • Thermoregulatory: high fever (>38.5°C).
  • Gastrointestinal: nausea, vomiting, diarrhoea, jaundice.

Investigations

  • Thyroid function tests: very low TSH, elevated free T4 and/or T3.
  • Electrolytes: assess for dehydration, hypercalcaemia, and lactic acidosis.
  • Liver function tests: may show deranged liver enzymes.
  • ECG: evaluate for tachyarrhythmias (e.g., atrial fibrillation).
  • Blood cultures: if sepsis is suspected.

Management

1. Emergency Supportive Care:

  • IV fluids: aggressive rehydration with crystalloids.
  • Cooling measures: antipyretics (excluding aspirin), cooling blankets.
  • Oxygen therapy: as needed for respiratory support.

2. Antithyroid Therapy:

  • Propylthiouracil (PTU): preferred over carbimazole in thyroid storm as it reduces peripheral T4 to T3 conversion.
  • Beta-blockers (e.g., propranolol): to control adrenergic symptoms.
  • Glucocorticoids (e.g., hydrocortisone): reduce T4 to T3 conversion and treat potential adrenal insufficiency.
  • Iodine (e.g., Lugol’s iodine): given after PTU to inhibit thyroid hormone release.

3. Address Underlying Cause:

  • Treat infections, discontinue iodine containing drugs, and manage precipitating conditions.

4. Referral:

  • Endocrinology: urgent referral for specialist management.
  • Cardiology: if atrial fibrillation or heart failure is present.
EndocrinologymypanotesHyperthyroid Crisis, thyroid storm