What is the initial management of hyperthyroidism (excessive thyroid hormone production) in the emergency setting?

Emergency Management of Hyperthyroidism

Beta-blockers are the cornerstone of initial emergency management for hyperthyroidism, with the goal of reducing heart rate to nearly normal (<90 bpm), followed by antithyroid medication (methimazole preferred) for definitive control of thyroid hormone synthesis. 1, 2

Immediate Stabilization

Beta-Blocker Therapy (First-Line)

• Initiate beta-blockers immediately for all symptomatic patients to control tachycardia, hypertension, tremor, and other adrenergic symptoms 1
• Atenolol 25-50 mg daily is preferred due to cardioselectivity 2
• Alternatively, propranolol can be used for symptomatic relief 1, 2
• Titrate dose to achieve heart rate <90 bpm if blood pressure tolerates 2
• For emergency situations, intravenous propranolol can prepare patients for surgery in less than one hour 3

Clinical Pearl: Beta-blockers provide rapid improvement in cardiac and neurologic symptoms without significantly affecting thyroid function itself, making them safe for immediate use while awaiting definitive diagnosis 1

Antithyroid Medication

Methimazole (Preferred Agent)

• Start methimazole 15 mg daily, divided into doses for mild to moderate hyperthyroidism 2
• Methimazole is preferred over propylthiouracil due to lower risk of severe hepatotoxicity 4, 5
• Monitor thyroid function (FT4 or TSH) every 2-4 weeks initially to guide dose adjustments 2

Propylthiouracil (Limited Role)

• Reserve propylthiouracil for first trimester pregnancy only or true methimazole allergy 4
• Propylthiouracil carries significant risk of hepatic failure, particularly in pediatric patients 4
• Patients must be counseled to immediately report signs of hepatic dysfunction (anorexia, pruritus, jaundice, right upper quadrant pain) 4

Severity-Based Approach

Mild to Moderate Symptoms (G1-G2)

• Continue with beta-blocker plus methimazole as outpatient 1, 2
• Provide hydration and supportive care 1
• Monitor thyroid function every 2-3 weeks after diagnosis 1, 2

Severe Symptoms or Thyroid Storm (G3-G4)

• Hospitalize immediately for severe cases with life-threatening consequences 1
• Obtain endocrine consultation urgently 1
• Administer beta-blockers, hydration, and supportive care 1
• Consider additional therapies including steroids, saturated solution of potassium iodide (SSKI), or thionamides 1
• Thyroid storm requires multidrug therapy targeting hormone synthesis, release, and peripheral effects 6

Critical Monitoring

Laboratory Surveillance

• Check TSH and free T4 for case detection in symptomatic patients 1
• T3 can be helpful in highly symptomatic patients with minimal FT4 elevations 1
• Monitor for agranulocytosis with white blood cell and differential counts if patients develop sore throat, fever, or general malaise 4, 5
• Monitor prothrombin time before surgical procedures due to potential hypoprothrombinemia 4, 5

Cardiovascular Complications

• Cardiovascular complications are the chief cause of death in patients >50 years with hyperthyroidism 1
• Hyperthyroidism can precipitate heart failure in patients with underlying cardiac disease 1
• Prompt recognition and effective management of cardiac manifestations is critical 1

Common Pitfalls to Avoid

• Do not delay beta-blocker therapy while awaiting thyroid function test results in symptomatic patients 1, 2
• Do not use propylthiouracil as first-line except in first trimester pregnancy due to hepatotoxicity risk 4
• Do not miss the transition to hypothyroidism in thyroiditis cases—monitor closely as this is the most common outcome 1
• Do not use radioactive iodine in the emergency setting—this is for definitive outpatient management 7, 8
• Warn patients to immediately report illness symptoms (sore throat, rash, fever) suggesting agranulocytosis 4, 5

Disposition Planning

• Most patients with mild-moderate symptoms can be managed outpatient with close endocrine follow-up 1
• Admit patients with severe symptoms, thyroid storm, or significant cardiovascular compromise 1
• Arrange endocrine consultation for persistent thyrotoxicosis beyond 6 weeks or diagnostic uncertainty 1
• Definitive treatment options (radioactive iodine, surgery) should be discussed after acute stabilization 7, 8