Hyperthyroid Crisis (Thyrotoxic Storm)

Thyrotoxic crisis is an uncommon (~1%) medical emergency caused by an exacerbation of hyperthyroidism characterised by decompensation of one or more organ systems.¹ Early recognition and aggressive treatment are essential. Thyroid storm can occur in patients with a toxic adenoma or multinodular toxic goitre, but is more often seen in patients with Graves' disease.

Often sudden onset of severe hyperthyroidism with:

• Hyperpyrexia (over 41 degrees C, dehydration)
• Heart rate greater than 145 beats per minute (with or without atrial fibrillation or other arrhythmia), hypotension, atrial dysrhythmias, congestive heart failure
• Nausea, jaundice, vomiting, diarrhoea, abdominal pain
• Confusion, agitation, delirium, psychosis, seizures or coma

Thyroid storm is most often seen in a thyrotoxic patient with intercurrent illness, trauma or emergency surgery. Common precipitants include:²

• Infection or other acute illness
• Withdrawal of or non-compliance with anti-thyroid medication
• Recent trauma, including surgical stress
• Myocardial infarction
• Diabetic ketoacidosis or hypoglycaemia
• Pulmonary embolism
• Drugs: radio-iodine, amiodarone, radiographic contrast media
• Recent thyroid surgery

• Blood: thyroid function tests, renal function and electrolytes (dehydration), glucose (hyperglycaemia), liver function tests (liver dysfunction), calcium (increased), full blood count (anaemia, thrombocytopenia, leucocytosis), blood culture
• Urine microscopy and culture (as part of infection screen)
• ECG
• Chest x-ray
• Arterial blood gases and pH

• Treatment of precipitating cause.
• Oxygen.
• Intravenous access and give 0.9% saline infusion. Adjust IV fluids as necessary, ideally guided by central venous pressure.
• Beta blockers (initially intravenous propranolol 5mg, then orally) unless contraindicated (e.g. asthma - but heart failure is not a contraindication). Diltiazem can be used if propranolol is contraindicated.
• Intravenous hydrocortisone - blocks T₄ to T₃ conversion.
• Nasogastric tube if vomiting.
• For severe agitation, sedate with chlorpromazine.
• Keep cool with tepid sponging and paracetamol. Avoid aspirin which can increase T₄.
• Treat heart failure:
  • High-dose digoxin may be needed.
  • Cardioversion will not be effective for atrial fibrillation until the patient is euthyroid.
  • Give frusemide or bumetanide as required, depending on degree of pulmonary oedema and of dehydration.
• Anticoagulation: prophylactic subcutaneous heparin to prevent thromboembolism; intravenous infusion if in atrial fibrillation.
• Antithyroid treatment: carbimazole or propylthiouracil orally. After 4 hours give Lugol's solution (aqueous iodine oral solution).
• Treat suspected infection.
• If patient fails to improve within 1-2 days, may need consider exchange transfusion, peritoneal dialysis or haemodialysis.
• Further thyroid management will depend on the progress of each individual patient and must be under the care of an endocrinologist.

The mortality of untreated thyrotoxic crisis is high. Even with earlier diagnosis the mortality is still 20-50%.³