How should I manage a patient with known hyperthyroidism who presents with fever, tachycardia, altered mental status, gastrointestinal upset, or heart failure suggestive of thyroid storm?

Thyroid Storm Management

Thyroid storm is a life-threatening endocrine emergency requiring immediate aggressive multi-drug therapy without waiting for laboratory confirmation—begin treatment based on clinical presentation alone, as mortality reaches 75% if delayed and 30% even with appropriate treatment. 1

Immediate Recognition and Diagnosis

Diagnose thyroid storm clinically based on the characteristic triad: hyperpyrexia (fever often >104°F/40°C), extreme tachycardia (typically >140 bpm), and altered mental status ranging from agitation to coma in a patient with known or suspected hyperthyroidism. 1, 2

Key Clinical Features to Identify

• Cardiovascular: Severe tachycardia, atrial fibrillation, congestive heart failure, or cardiogenic shock 1
• Thermoregulatory: Marked fever >104°F, profuse sweating 1
• Neuropsychiatric: Altered mental status (agitation, confusion, seizures, or coma), extreme nervousness, tremors 1
• Gastrointestinal: Vomiting, diarrhea, or markedly increased ileostomy output 3, 1, 4
• Multiorgan decompensation: Cardiovascular collapse, renal insufficiency, hepatic dysfunction, coagulopathy 1

Common Precipitating Factors

Look for these triggers: infection, acute medical illness, medication non-adherence in known hyperthyroid patients, pregnancy/labor/delivery, surgery, or trauma. 3, 1, 2

Critical Pitfall: Do Not Delay Treatment

Laboratory confirmation is not required—begin treatment immediately based on clinical suspicion. There is no single laboratory value that establishes the diagnosis. 2 While you should order serum free T3, free T4, and TSH to confirm hyperthyroidism, treatment must not be delayed for results. 3

Immediate Treatment Protocol

1. Resuscitation and Supportive Care (Start Simultaneously)

• Oxygen therapy and appropriate hemodynamic monitoring 3
• Aggressive cooling measures for hyperpyrexia—use antipyretics (acetaminophen preferred; avoid aspirin as it displaces thyroid hormone from binding proteins) 3
• Intravenous fluids for volume resuscitation 2
• Treat the precipitating cause (e.g., antibiotics for infection) 3, 1

2. Beta-Blocker Administration (First-Line Rate Control)

Administer beta-blockers immediately unless severe heart failure is present. 3, 2 Propranolol is preferred because it also blocks peripheral conversion of T4 to T3. 3

• High doses may be required in thyroid storm, particularly for aggressive rate control 3
• In severe heart failure: Use digoxin for rate control instead, or consider diltiazem/verapamil if beta-blockers are contraindicated 3

3. Thionamide Therapy (Block New Hormone Synthesis)

Administer propylthiouracil (PTU) or methimazole immediately to block new thyroid hormone synthesis. 3, 2

• PTU is often preferred in thyroid storm because it also blocks peripheral T4-to-T3 conversion 3
• Critical timing: Give thionamide at least 1 hour BEFORE iodine administration to prevent iodine from being used as substrate for new hormone synthesis 3

4. Iodine Administration (Block Hormone Release)

Give saturated solution of potassium iodide (SSKI), sodium iodide, or Lugol's solution at least 1 hour AFTER thionamide to block release of preformed thyroid hormone. 3

• Alternatives if iodine cannot be used: lithium, diltiazem 3
• Never give iodine before thionamides—this is a critical error that can worsen thyroid storm 3

5. Corticosteroid Therapy

Administer dexamethasone or hydrocortisone to block peripheral T4-to-T3 conversion, treat potential relative adrenal insufficiency, and control systemic inflammatory reactions. 3, 5

• Steroids provide additional benefit beyond standard antithyroid therapy 5
• Steroid pulse therapy may be particularly beneficial in severe cases with hemodynamic collapse 5

6. Additional Adjunctive Therapies

• Cholestyramine or bile acid sequestrants to interrupt enterohepatic circulation of thyroid hormones 2
• Phenobarbital for severe agitation (also enhances thyroid hormone metabolism) 3
• Reserpine or guanethidine in patients with history of severe bronchospasm where beta-blockers are contraindicated 3

Cardiovascular Complications Require Special Attention

Thyroid storm causes profound cardiovascular stress through multiple mechanisms: increased cardiac output (up to 300% above normal), reduced systemic vascular resistance, paradoxical pulmonary hypertension, and potential for both high-output heart failure and cardiogenic shock. 1

• In older patients with pre-existing cardiac disease, the additional workload can precipitate decompensated heart failure—this is the leading cause of mortality after treatment 1
• Monitor closely for: atrial fibrillation, rapid ventricular rates, tachycardia-induced cardiomyopathy, and right ventricular failure from pulmonary hypertension 1

Pregnancy Considerations

Thyroid storm affects <1% of pregnant women with hyperthyroidism but carries extremely high maternal and fetal mortality. 3, 1

• Avoid delivery during thyroid storm unless absolutely necessary 3
• Evaluate fetal status with ultrasound, nonstress testing, or biophysical profile depending on gestational age 3
• All standard thyroid storm medications can be used in pregnancy, though I-131 is absolutely contraindicated 3

Anticoagulation for Atrial Fibrillation

If atrial fibrillation develops with thyrotoxicosis, use oral anticoagulation (INR 2-3) to prevent thromboembolism based on CHA2DS2-VASc risk factors, just as you would for AF patients with other stroke risk factors. 3

Critical Care and Monitoring

Prepare for rapid clinical deterioration—employ a multidisciplinary approach involving critical care and endocrinology specialists immediately. 2

• Thyroid storm represents multiorgan system decompensation requiring ICU-level care 1
• Mortality remains 30% even with appropriate treatment, underscoring the importance of aggressive early intervention 1

Common Diagnostic Mimics to Exclude

Consider these alternative diagnoses that can present similarly: sympathomimetic overdose, substance use disorders, alcohol withdrawal, acute pulmonary edema, aortic dissection, heat stroke, serotonin syndrome, and sepsis/septic shock. 2