Thyrotoxic storm is the abrupt and severe exacerbation of thyrotoxicosis. It is an acute, life-threatening complication of hyperthyroidism.

Thyroid storm

• Tremor, tachycardia/tachyarrhythmias, fever (as high as 105.8° F [41° C])
• Sweating, diarrhea, vasodilation
• Lid lag, lid retraction, proptosis
• Altered mental status (psychosis, coma, seizures)
• Goiter
• Other: Evidence of precipitating factors (infection, trauma), congestive heart failure [CHF], hepatosplenomegaly, jaundice

• Precipitating factors: Surgery, infection, myocardial infarction or cardiac disease, diabetic ketoacidosis, labor, iodinated IV contrast agents, radioactive iodine therapy
• Inadequate therapy in a hyperthyroid patient

• Psychiatric disorders
• Alcohol or other drug withdrawal
• Pheochromocytoma
• Metastatic neoplasm

• Laboratory evaluation to confirm hyperthyroidism (elevated free T4, decreased thyroid-stimulating hormone [TSH])
• Evaluation for precipitating factors (e.g., ECG and cardiac enzymes in suspected MI, blood and urine cultures to rule out sepsis)
• Elimination of disorders noted in the differential diagnosis (e.g., psychiatric history, evidence of drug and alcohol abuse)

• Free T₄, TSH
• Complete blood count with differential
• Blood and urine cultures
• Glucose
• Liver enzymes
• Blood urea nitrogen, creatinine
• Serum calcium
• Creatine phosphokinase

Chest x-ray to exclude infectious process, neoplasm, CHF in suspected cases

• Nutritional care: Replace fluid deficit aggressively (daily fluid requirement may reach 6 L); use solutions containing glucose and add multivitamins to the hydrating solution.
• Monitor for fluid overload and CHF in the elderly and in those with underlying cardiovascular or renal disease.
• Treat significant hyperthermia with cooling blankets.

• Inhibition of thyroid hormone synthesis:
  1. Administer propylthiouracil (PTU) 800 mg initially (PO or by nasogastric tube)/PR, then 200 to 300 mg PO/PR q6h. PTU is preferred over methimazole because it has the added benefit of blocking peripheral conversion of T₄ to T₃
  2. If the patient is allergic to PTU, use methimazole 80 to 100 mg (PO or by nasogastric tube)/PR followed by 40 mg PO/PR q8h. Methimazole can also be administered IV 60 to 120 mg daily, divided doses
• Inhibition of stored thyroid hormone release from the gland:
  1. Sodium iodide 1 g IV over 24 hr or potassium iodide (oral) 5 drops 4 times/day (super-saturated potassium iodide). It is important to administer PTU or methimazole 1 hr before the iodide to prevent the oxidation of iodide to iodine and its incorporation in the synthesis of additional thyroid hormone
  2. Corticosteroids: Dexamethasone 1 to 2 mg IV q6h or hydrocortisone 100 mg IV q6h for approximately 48 hr is useful to inhibit thyroid hormone release, impair peripheral conversion of T₃ from T₄, and provide additional adrenocortical hormone to correct deficiency (if present)
• Suppression of peripheral effects of thyroid hormone:
  1. Beta-adrenergic blockers: Administer propranolol 60 to 80 mg every 4 hr. Propranolol may also be given IV 1 mg/min for 2 to 10 min under continuous ECG and blood pressure monitoring. Beta-adrenergic blockers must be used with caution in patients with severe CHF or bronchospasm. Cardioselective beta-blockers (e.g., esmolol 500 mg IV over 1 min, then 50 to 100 mg/kg/min or metoprolol 5 to 10 mg IV every 2 to 4 hr) may be more appropriate for patients with bronchospasm, but these patients must be closely monitored for exacerbation of bronchospasm because these agents lose their cardioselectivity at high doses. The calcium channel blocker diltiazem can also be given to reduce the heart rate. Dose is 0.25 mg/kg over 2 min, then infusion of 10 mg/min. Oral dose is 60 to 90 mg every 6 to 8 hr
• Control of fever with acetaminophen 325 to 650 mg q4h; avoidance of aspirin because it displaces thyroid hormone from its binding protein
• Treatment of any precipitating factors (e.g., antibiotics if infection is strongly suspected)

Patients with thyrotoxic crisis should be treated and appropriately monitored in the ICU.

Endocrinology referral is appropriate in patients with thyrotoxic crisis.

If the diagnosis is strongly suspected, therapy should be started immediately without waiting for laboratory confirmation.

Graves Disease (Related Key Topic)

Hyperthyroidism (Related Key Topic)