What are the treatment options for hyperthyroidism?

Treatment of Hyperthyroidism

Methimazole is the preferred first-line antithyroid drug for hyperthyroidism due to superior efficacy and safety, except during the first trimester of pregnancy when propylthiouracil must be used. 1

Treatment Modalities

There are three primary treatment options for hyperthyroidism, each with specific indications:

First-Line Medical Therapy

• Methimazole is the antithyroid drug of choice for most patients with Graves' disease or toxic nodular goiter due to its longer half-life, once-daily dosing, and lower risk of severe side effects compared to propylthiouracil 1, 2

• Propylthiouracil is reserved for specific situations only: 3

  • First trimester of pregnancy (to avoid methimazole-associated birth defects)
  • Patients intolerant to methimazole
  • Preparation for surgery or radioactive iodine when methimazole cannot be used

• Critical warning about propylthiouracil: This drug carries a black box warning for severe liver problems, including liver failure requiring transplant or causing death, particularly in pregnant women and their infants 3

Symptom Management During Initial Treatment

• Beta-blockers provide immediate symptomatic relief while awaiting thyroid hormone normalization 1
  • Atenolol 25-50 mg daily or propranolol are recommended options
  • Particularly useful for controlling tachycardia, tremor, and anxiety symptoms
  • Dose reduction needed once euthyroid state is achieved 1

Definitive Treatment Options

Radioactive iodine (I-131) ablation:

• Most widely used treatment in the United States for definitive management 4
• Treatment of choice for toxic nodular goiter 5
• Well tolerated with only long-term risk being hypothyroidism 5
• Absolutely contraindicated in pregnancy and breastfeeding 6
• Pregnancy must be avoided for 4 months following administration 5
• May worsen Graves' ophthalmopathy; corticosteroid cover can reduce this risk 5

Surgical thyroidectomy:

• Reserved for specific situations 5, 4:
  • Large goiter causing compressive symptoms
  • Patient refusal of radioactive iodine
  • Contraindications to other treatment modalities
• Subtotal or near-total thyroidectomy options available

Treatment Duration and Monitoring

• For Graves' disease treated with antithyroid drugs: Standard course is 12-18 months, though approximately 50% of patients experience recurrence 7

• Long-term antithyroid drug therapy (5-10 years) is associated with lower recurrence rates (15%) compared to short-term treatment 7

• Monitor free T4 or free T3 index every 2-4 weeks during initial treatment to maintain levels in the high-normal range using the lowest effective dose 6

Special Considerations for Destructive Thyroiditis

• Self-limited condition requiring different management 1
• Beta-blockers for symptomatic relief only
• No indication for antithyroid drugs as this represents passive hormone release, not overproduction 1

Important Drug Interactions

• Warfarin requires dose adjustment due to increased anticoagulation effect when taking antithyroid drugs 1
• Theophylline clearance decreases when patient becomes euthyroid 1
• Digoxin levels may be affected 3

Critical Monitoring for Adverse Effects

For patients on thioamides (methimazole or propylthiouracil):

• Agranulocytosis typically occurs within first 3 months 6, 3

  • Presents with sore throat and fever
  • Requires immediate CBC and drug discontinuation

• Hepatotoxicity (especially with propylthiouracil) 3

  • Monitor for fever, nausea, vomiting, right upper quadrant pain, dark urine, jaundice
  • Stop drug immediately if suspected

• Vasculitis can be life-threatening 3

  • Watch for skin changes, hematuria, or respiratory symptoms