Thyroid storm
Thyroid storm is a severe excess of thyroid hormone, usually occurring as a result of untreated or inadequately treated thyrotoxicosis, or a severe acute systemic illness. It is a life-threatening emergency—arrange immediate transport to hospital by ambulance. Thyroid storm usually presents with marked symptoms including fever, tachycardia, vomiting, dehydration, delirium, coma, and organ system dysfunction (especially hepatic). It can also be complicated by stroke, including cerebral venous thrombosis.
In addition to identifying and treating any underlying causes of thyroid storm, treatment involves:
- controlling tachycardia and rate-dependent heart failure
- blocking hormone synthesis
- decreasing conversion of thyroxine (T4) to triiodothyronine (T3)
- blocking hormone release
- restoring hydration
- providing sedation if required.
Control tachycardia with a beta blocker. A suitable oral option is:
propranolol 40 to 80 mg orally, 4 times daily. thyroid storm propranolol
Intravenous therapy provides a more rapid onset of action; suitable options include:
1 esmolol 250 to 500 micrograms/kg intravenously, as a loading dose, followed by 50 to 100 micrograms/kg/minute by continuous intravenous infusion thyroid storm
OR
1 metoprolol 5 mg intravenously over 2 to 3 minutes, repeated if necessary at 5-minute intervals up to a total of 15 mg. thyroid storm metoprolol
Antithyroid drugs block the synthesis of thyroid hormones. Propylthiouracil is preferred to carbimazole for the treatment of thyroid storm because in high doses it also blocks the conversion of T4 to T3. Use:
1 propylthiouracil 200 mg orally, 4- to 6-hourly thyroid storm propylthiouracil
OR
2 carbimazole 20 mg orally, 6- to 8-hourly. thyroid storm carbimazole
Further dose adjustment depends on clinical and hormonal responses to treatment. If oral therapy with propylthiouracil is not possible, rectal administration is also effective.
In addition to the antithyroid drug, block the release of thyroid hormone with:
iodine 5% + potassium iodide 10% in water (Lugol solution) 0.5 mL orally, 3 times daily1. thyroid storm
Also consider using dexamethasone to reduce the conversion of T4 to T3. Use:
dexamethasone 4 mg orally or intravenously, 12-hourly. thyroid storm dexamethasone
Severe or refractory thyrotoxicosis sometimes requires additional therapy (see Other treatments for thyrotoxicosis).