Thyroid storm is a rare but life-threatening complication of thyrotoxicosis. It is typically seen in patients with established thyrotoxicosis and is rarely seen as the presenting feature. Iatrogenic thyroxine excess does not usually result in thyroid storm.

Precipitating events:

• thyroid or non-thyroidal surgery
• trauma
• infection
• acute iodine load e.g. CT contrast media

Clinical features include:

• fever > 38.5ºC
• tachycardia
• confusion and agitation
• nausea and vomiting
• hypertension
• heart failure
• abnormal liver function test - jaundice may be seen clinically

Management:

Management of thyrotoxic storm involves the following steps:

1. Symptom control:
   • IV propanolol
   • IV digoxin if propanolol fails or is contraindicated (e.g. asthma, low BP)
2. Reduce thyroid activity:
   • Propylthiouracil - preferred because it inhibits peripheral thyroxine conversion
   • Lugol's iodine 4 hours later
   • Methimazole/carbimazole is considered second-line
   • IV hydrocortisone to reduce thyroid inflammation