Thyroid Storm

The Concept

Thyroid storm (thyrotoxic crisis) is a rare, life-threatening exacerbation of thyrotoxicosis — an abrupt, extreme escalation of the effects of thyroid hormone that can be fatal from cardiovascular collapse or hyperthermia. Its importance to the surgeon is that it is classically precipitated by the stress of surgery, infection, trauma or childbirth in a thyrotoxic patient who was inadequately prepared — which is precisely why rendering a patient euthyroid before thyroid surgery is so emphasised.

Clinical Features

It is a clinical diagnosis based on a severe, decompensated hypermetabolic state: high fever (hyperpyrexia), marked tachycardia and tachyarrhythmias (often atrial fibrillation), heart failure, agitation, delirium or coma, and gastrointestinal features (vomiting, diarrhoea, and sometimes jaundice). Untreated, the combination of hyperthermia and cardiovascular strain is frequently fatal, so treatment is started on clinical suspicion without waiting for confirmatory tests.

Management

Treatment is urgent and multi-pronged, attacking the hormone at every level plus supportive care:

• Beta-blockade — propranolol — to control the sympathetic and cardiac effects (also reduces peripheral T4→T3 conversion).
• Antithyroid drug — carbimazole or propylthiouracil — to block new hormone synthesis (PTH also blocks T4→T3 conversion).
• Lugol's iodine — to block hormone release, given after the antithyroid drug (to avoid fuelling the gland).
• Hydrocortisone — reduces T4→T3 conversion and treats any relative adrenal insufficiency.
• Supportive care — active cooling, IV fluids, oxygen, treat the precipitant (e.g. Infection), and manage in a high-dependency setting.

A Note on Recognition

The key to surviving thyroid storm is early recognition and not waiting for laboratory confirmation — scoring systems (such as the Burch-Wartofsky score) grade the likelihood, but treatment is begun on clinical suspicion in any thyrotoxic patient who develops fever, extreme tachycardia and altered mental state after a stressor. Because it is largely preventable, the emphasis remains on adequate pre-operative preparation of every thyrotoxic patient before elective thyroid or other major surgery.

Recognition & Prevention

The keys to thyroid storm are recognition and prevention. It is a clinical diagnosis (aided by scoring systems such as Burch-Wartofsky) treated on suspicion, because waiting for confirmation costs lives. Most cases are preventable by ensuring any thyrotoxic patient is rendered euthyroid — with antithyroid drugs, a beta-blocker and, before thyroid surgery, Lugol's iodine — prior to elective surgery, and by promptly treating precipitants such as infection. In the emergency setting, the combination of a beta-blocker, an antithyroid drug, iodine (after the antithyroid drug), corticosteroids and aggressive supportive care is instituted at once.

The Bottom Line

Ultimately thyroid storm is a preventable emergency: render every thyrotoxic patient euthyroid before elective surgery, treat precipitants promptly, and, if it occurs, begin the multi-drug regimen (beta-blocker, antithyroid drug, iodine after the antithyroid drug, corticosteroid) plus supportive care on clinical suspicion without waiting for confirmation.

Treat on clinical suspicion — do not await thyroid function results.

• Thyroid storm = life-threatening exacerbation of thyrotoxicosis; precipitated by surgery/infection/trauma in an inadequately prepared patient.
• Features: hyperpyrexia, severe tachycardia/AF, heart failure, agitation/delirium, vomiting — treat on clinical suspicion.
• Manage: propranolol + antithyroid drug (carbimazole/PTU) + Lugol's iodine (after the antithyroid drug) + hydrocortisone.
• Plus supportive care: cooling, fluids, oxygen, treat the precipitant.
• Prevented by rendering thyrotoxic patients euthyroid (+ Lugol's iodine) before surgery.