What is the treatment for hyperthyroidism?

Treatment of Hyperthyroidism

Methimazole is the preferred first-line medication for hyperthyroidism, with an initial dose of 10-30 mg daily for a standard course of 12-18 months. 1 Treatment should be initiated for all patients with overt hyperthyroidism and even subclinical hyperthyroidism with TSH <0.1 mIU/L due to increased cardiovascular risks. 1

Diagnosis Confirmation

Before initiating treatment, confirm hyperthyroidism with:

• Suppressed TSH
• Elevated Free T4 and/or Free T3
• Determine etiology through:
  • Clinical presentation
  • TSH receptor antibodies
  • Thyroid ultrasonography
  • Thyroid scintigraphy (if nodules present or etiology unclear) 1, 2

Treatment Options

First-Line Medication Therapy

1. Methimazole (MMI)

   • Preferred first-line agent 1
   • Dosing: 10-30 mg once daily 1, 3
   • Duration: Standard course of 12-18 months 1
   • Mechanism: Inhibits thyroid hormone synthesis 3
   • More effective than propylthiouracil at equivalent doses 4
   • Potential side effects: Agranulocytosis, skin eruptions, hepatotoxicity 1

2. Propylthiouracil (PTU)

   • Alternative treatment, particularly in first trimester of pregnancy 1, 5
   • Dosing: 100-300 mg divided three times daily 1
   • Additional benefit: Inhibits peripheral conversion of T4 to T3 (beneficial in thyroid storm) 5
   • Serious risks: Severe liver problems including liver failure requiring transplant 5
   • FDA black box warning for liver toxicity 5

3. Beta-blockers

   • Indicated for all symptomatic patients 1
   • Addresses palpitations, tremor, anxiety, and tachycardia 1
   • Options include atenolol or propranolol 1
   • Potential side effects: Bradycardia, bronchospasm, hypotension 1

Definitive Treatment Options

1. Radioactive Iodine Ablation

   • Most widely used treatment in the United States 6
   • Particularly effective for toxic nodular goiter 1
   • Contraindicated in pregnancy 1
   • Often leads to permanent hypothyroidism requiring lifelong thyroid hormone replacement

2. Surgical Thyroidectomy

   • Indicated for:
     • Large goiters causing compressive symptoms
     • Suspicious nodules
     • Patients who decline radioactive iodine
     • Pregnant women who cannot tolerate antithyroid drugs 1
   • Potential complications: Hypoparathyroidism and recurrent laryngeal nerve injury 1

Special Populations

Pregnancy

• First trimester: Propylthiouracil is preferred 1, 5
• Second and third trimesters: Switch to methimazole 1
• Use lowest effective dose 1
• Radioactive iodine is absolutely contraindicated 1
• Surgical thyroidectomy may be considered if medication intolerance 1

Subclinical Hyperthyroidism

• Treatment recommended for:
  • TSH <0.1 mIU/L
  • Patients over 65 years
  • Those at risk of cardiovascular complications 1, 7

Monitoring and Follow-up

• Initial monitoring: Every 2-3 weeks until stable 1
• Maintenance monitoring: Every 1-3 months 1
• Adjust medication dose based on thyroid function tests 1
• Monitor for medication side effects:
  • Complete blood count (for agranulocytosis)
  • Liver function tests (for hepatotoxicity)
  • Skin examination (for eruptions) 1

Common Pitfalls to Avoid

• Failing to recognize thyroid storm (life-threatening emergency requiring immediate intensive care) 1
• Missing the underlying cause of hyperthyroidism 1
• Overlooking pregnancy status before selecting treatment 1
• Inadequate monitoring of thyroid function and medication side effects 1
• Ignoring cardiovascular complications 1
• Using radioactive iodine in pregnant women 1

Long-term Considerations

• Recurrence rate after 12-18 months of antithyroid drugs is approximately 50% 2
• Risk factors for recurrence: Age <40 years, FT4 ≥40 pmol/L, high TSH-binding inhibitory immunoglobulins, larger goiter 2
• Long-term treatment (5-10 years) with antithyroid drugs is associated with fewer recurrences (15%) 2