This patient is suffering from a thyrotoxic crisis (Thyroid storm).
Thyroid storm is a relatively rare diagnosis, occurring in 1-2% of patients with established hyperthyroidism. It is an important diagnosis not to miss, however, because of the high mortality rate associated with it (approximately 10%).
Thyrotoxic crisis classically occurs in patients with underlying Graves’ disease or toxic multinodular goitre. Often, there is sudden onset of severe hyperthyroidism with:
- Hyperpyrexia (over 41°C), dehydration.
- Heart rate greater than 140 beats per minute (with or without atrial fibrillation or other arrhythmias), hypotension, atrial dysrhythmias, congestive heart failure.
- Nausea, jaundice, vomiting, diarrhoea, abdominal pain.
- Confusion, agitation, delirium, psychosis, seizures or coma.
In this case it would appear that the sudden discontinuation of her carbimazole has precipitated her condition.
Thyroid storm is often precipitated by a physiological stressor, such as:
- Premature or inappropriate cessation of anti-thyroid therapy
- Recent surgery or radio-iodine treatment
- Intercurrent infection (especially chest infections)
- Diabetic ketoacidosis or hyperosmolar diabetic crisis
- Thyroid hormone overdose
Blood tests that should be organized include:
- Full blood count
- Urea and electrolytes
- Blood glucose or bedside BM
- Coagulation screen
- Thyroid profile (T4/T3 and TSH)
- Bone profile / calcium (10% of patients develop hypocalcaemia)
- Blood cultures
Other important investigations that should be organized include:
- Urine dipstick / MC&S
- Chest X-ray
The management of thyroid storm should include the following:
- Commence IV fluids e.g. 1-2 litres 0.9% saline
- Support and manage airway as appropriate
- Pass nasogastric tube (as patient is vomiting)
- Refer urgently for inpatient management
- Paracetamol 1 g PO/IV for pyrexia
- Benzodiazepines for sedation e.g. diazepam 5-20 mg PO/IV
- Steroids for co-existing adrenal suppression e.g. hydrocortisone 100 mg IV
- Antibiotics if intercurrent infection present
- Beta-blockers e.g. propranolol 80 mg PO
- High dose carbimazole 45-60 mg/day
- Potassium iodide 200 mg IV over 1 hour (blocks release of thyroid hormones)