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Information ⬇

Author(s): James Crane and Paul Carroll

Consider the diagnosis in any patient with fever, abnormal mental state, sinus tachycardia or atrial fibrillation, who also has signs of thyrotoxicosis. Thyrotoxic storm is an acute life-threatening metabolic emergency caused by extremely high levels of thyroid hormone activity. If the diagnosis is suspected, antithyroid treatment must be started before biochemical confirmation. Adequate beta blockade to neutralize the associated autonomic overdrive is also essential.

Thyrotoxicosis is the syndrome resulting from supranormal thyroid hormone activity, and is usually the result of hyperthyroidism, defined as increased thyroid hormone production by the native thyroid gland. Causes are summarized in Table 91.1.

Priorities ⬆ ⬇

Is This Thyrotoxic Storm?

  • The diagnosis of thyrotoxic storm is clinical, and rests on the identification of actual or impending decompensation of organ function due to thyrotoxicosis (Table 91.2).
  • Since thyroid storm represents the end of a spectrum of severity, and due to inter-patient differences in the tipping point between compensated organ stress and decompensated organ failure, the diagnosis may be difficult.

What Has Triggered the Thyrotoxic Storm?

  • Thyrotoxic storm may occur in the course of the natural history of an underlying thyrotoxic process, but is more often related to decompensation caused by an intercurrent precipitant. This is most frequently an infective illness, but may also be surgery (particularly thyroid surgery or occasionally non-thyroid surgery), other critical illness or childbirth.
  • Other iatrogenic causes include radioactive iodine therapy in patients with insufficiently controlled hyperthyroidism, abrupt cessation of antithyroid medications (or non-adherence to these), administration of iodine-containing pharmaceuticals (e.g. amiodarone or contrast agents), induction of anaesthesia or repeated vigorous palpation of a Graves' goitre.

Immediate Management

Thyrotoxic storm is an acutely life-threatening condition and must be managed in a level 2 or 3 (resuscitation area/HDU/ICU) setting. The immediate management priorities in the first hour are:

  • Rapid assessment of airway, breathing, circulation and conscious level. Continuous monitoring of blood pressure, heart rate and ECG.
  • Airway management by competent staff if the airway is compromised or the Glasgow Coma Scale score is less than 8.
  • Supplemental oxygen if needed to maintain arterial oxygen saturation 94–96%.
  • Haemodynamic stabilization. Hypotension may be due to high output cardiac failure or a compromising tachyarrhythmia (usually supraventricular). DC cardioversion may well be unsuccessful for AF in a severely hyperthyroid patient. Unless there is clinical suspicion of underlying cardiomyopathy, rate-related failure may be managed with a short-acting beta blocker (e.g. IV esmolol) with prompt withdrawal if clinical state worsens. Patients with thyrotoxic storm and heart failure must be managed in a level 3 environment, with continuous BP and CVP monitoring.
  • Assessment for common precipitants of thyrotoxic storm: sepsis, diabetic ketoacidosis, or myocardial infarction (see above). If identified, appropriate management should be initiated. When no precipitating factor is apparent, broad-spectrum antibiotics are warranted until intercurrent infection has been excluded. Other precipitating causes can be managed in the usual manner.
  • Cooling measures should be employed to correct fever, initially with paracetamol 1000 mg PO/IV.
  • Administer a non-cardioselective beta blocker, for example propranolol 40–80 mg PO. If rapid onset of action needed or if oral route unavailable due to reduced conscious level, intravenous esmolol 50–100μgm/kg/min may be used. Consider an arterial line for continuous blood pressure monitoring if IV beta blockers initiated.
  • Administer a thionamide to prevent further thyroid hormone production, for example propylthiouracil 500–1000 mg loading dose PO (followed by 250 mg 4-hourly). Carbimazole may also be used (20–30 mg every 4–6h PO). There are no intravenous preparations but they may be given via nasogastric tube or rectally if there are concerns about absorption.
  • Administer 100 mg IV hydrocortisone to support circulation and reduce thyroid hormone action.
  • Transfer to HDU/ICU for further management

Further Management ⬆ ⬇

  • The ongoing management of thyroid storm is directed towards blocking further production of thyroid hormone, blocking its release, blocking conversion of T4 to active T3 and limiting the adrenergic effects of high thyroid hormone activity. Thionamide treatment should be continued. Propylthiouracil at a dose of 250 mg every 4–6h has been the preferred agent due to its additional benefit in reducing conversion of T4 to T3. Recent concerns regarding an association between propylthiouracil and hepatitis should be taken into account and in patients with known liver disease or if liver function tests become abnormal, carbimazole 60–80 mg daily is an alternative. ‘Cold’ iodine (i.e. non-radioactive iodine) can be administered in the form of 3–5 drops of Lugol's solution (5% elemental iodine, 10% potassium iodide in distilled water) or a saturated solution of potassium iodide (SSKI), diluted in water three times daily, making use of the Wolff-Chaikoff effect in which high doses of iodine result in a blockade of the incorporation of iodine into thyroglobulin. Effectiveness of iodine solutions is time-limited to around ten days, after which the thyroid escapes this effect by down-regulating iodine transporters.
  • A beta blocker should be administered to negate the catecholaminergic effects of thyrotoxicosis. Oral propranolol is most frequently used due to its additional capacity to block peripheral T4 to T3 conversion. The dose is titrated according to cardiovascular parameters. In thyrotoxic storm, 60–120 mg 6-hourly PO may be required. Glucocorticoids also reduce peripheral conversion of T4 to T3: hydrocortisone 100 mg 6-hourly IV would be a typical dose.
  • In extreme, treatment refractory thyrotoxicosis, plasmapheresis has been used to clear circulating thyroid hormones to allow a window for emergency thyroidectomy to be performed safely.

Further Reading ⬆

De Leo S, Lee SY, Braverman LE (2016) Hyperthyroidism.pdf Lancet 388, 906–918.

Sharp CS, Wilson MP, Nordstrom K (2016) Psychiatric emergencies for clinicians: The Emergency Department management of thyroid storm. J Emerg Med 51, 155–158.