23rd May 2025

Thyrotoxic crisis (storm)

• A thyrotoxic crisis is  a rare but life-threatening exacerbation of thyrotoxicosis. Mortality can reach 30-50%. Some data shows higher predominance in females especially in pubertal children.
• It occurs as a response to stressful conditions e.g., infection, DKA, gland trauma, pregnancy, surgical treatments or during radioiodine treatment. Other causes can be excessive thyroid hormone ingestion or non-compliance with ATDs.

Clinical picture

Patients with thyroid storms are generally unwell, presenting with fever, altered mental status with tachycardia or tachyarrhythmias. Multisystem decompensation can occur, which can be fatal. This entails cardiac failure/arrhythmias, respiratory distress, congestive hepatomegaly (causing jaundice), dehydration and pre-renal failure (due to vomiting and diarrhoea). Patients may also exhibit neurological dysfunction in the form of severe agitation, delirium, seizures, and coma.

Investigations

The diagnosis of a thyroid crisis is based on clinical features, not on laboratory findings. So, in suspicion of a thyroid storm, treatment should not be delayed whilst awaiting blood results. 

• ECG: will show AF which is the commonest form of arrhythmia occurring in thyroid storms.
• Full blood count (FBC): Can show signs of infection.
• Biochemical screen: Electrolyte disturbance and renal failure may be seen. Raised liver transaminases and bilirubin and raised Ca+2.
• TFTs: Thyroid hormones are elevated, with suppressed TSH. Thyroid antibodies can be present.

Management

Treating thyroid storm must address two aspects: stabilisation of the patient; and management of the underlying thyroid pathology:

• Resuscitation, supportive therapy, and treatment of the cause which involves:
  • Best management is delivered in ITU for better monitoring of the cardiorespiratory status and fluid balance.
  • Electrolyte imbalance should be corrected.
  • If the patient develops AF, arrhythmia management and anticoagulation should be considered. 
    • Usually, high dose propranolol 160-480mg/day is given in divided doses as PO or IV. 
    • Cardio-selective β-blockers can be used as alternatives in patients with reactive airway disease.
    • Calcium channel blockers are another alternative.
  • In a state of infection, broad spectrum antibiotics should be started.
  • Chlorpromazine (50-100mg IM) has shown effect in treating agitation and hyperpyrexia. Hyperthermia can be treated by applying ice packs and cooling blankets.
• Treatment of the thyrotoxic state, which aims to inhibit thyroid hormone synthesis completely. Hence, the following should be given:
  • Propylthiouracil 200-300mg 6 hourly via NG. 
    • It has the ability to block peripheral conversion of T4 to T3. 
    • High dose carbimazole NG 45-60mg/d can be an alternative.
  • Potassium iodide 60mg NG 6 hourly and started after 6 hours from the propylthiouracil. 
    • It inhibits thyroid hormone release.
  • High dose of glucocorticoids (Prednisolone 60mg/day or hydrocortisone 400mg IM QDS)
    • Blocks T4 to T3 conversion.
  • Cholestyramine (3g TDS) 
    • Improves thyrotoxicosis by reducing enterohepatic circulation of thyroid hormones.