What is the recommended management for hyperthyroidism?

Management of Hyperthyroidism

The recommended first-line management for hyperthyroidism includes antithyroid medications (methimazole or propylthiouracil), radioactive iodine ablation, or surgical thyroidectomy, with the choice depending on the underlying cause, patient factors, and treatment goals. 1, 2

Diagnostic Approach

1. Confirm hyperthyroidism biochemically:

   • Measure TSH (primary screening test)
   • Measure free T4 simultaneously
   • Consider free T3 if TSH is suppressed but free T4 is normal
   • Repeat abnormal tests over 3-6 months to confirm 1

2. Determine etiology:

   • Graves' disease (70% of cases)
   • Toxic nodular goiter (16% of cases)
   • Thyroiditis (3% of cases)
   • Drug-induced (9% of cases) 3

Treatment Algorithm

1. Antithyroid Medications

• Methimazole (preferred option):

  • Inhibits synthesis of thyroid hormones
  • Does not inactivate existing thyroid hormones
  • Readily absorbed in GI tract, metabolized in liver 4
  • Typical dosing:
    • Initial: Based on severity
    • Maintenance: Adjust to maintain TSH in target range 1

• Propylthiouracil:

  • Alternative to methimazole
  • Preferred in first trimester of pregnancy due to lower risk of congenital malformations 4

• Duration:

  • Standard course: 12-18 months (50% recurrence rate)
  • Long-term treatment (5-10 years): 15% recurrence rate 3

2. Radioactive Iodine Ablation

• Most widely used treatment in the United States
• Particularly effective for toxic nodular goiter
• Contraindicated in pregnancy 5

3. Surgical Thyroidectomy

• Indicated for large goiters, suspected malignancy, or patient preference
• Requires preoperative preparation with antithyroid drugs 3

Adjunctive Treatments

• Beta-blockers (e.g., propranolol 60-80 mg orally every 4-6 hours):

  • Control adrenergic symptoms until methimazole reduces thyroid hormone levels
  • Dose reduction needed when patient becomes euthyroid 1, 4

• Non-dihydropyridine calcium channel blockers (diltiazem or verapamil):

  • Alternative when beta-blockers are contraindicated 1

Special Populations

Pregnancy

• Methimazole contraindicated in first trimester (pregnancy category D)
• Use propylthiouracil in first trimester
• Switch to methimazole for second and third trimesters
• Monitor TSH every 6-8 weeks during pregnancy
• Target TSH: 0.5-2.0 mIU/L 1, 4

Elderly Patients

• Higher risk of complications (atrial fibrillation, osteoporosis)
• Start with lower doses of antithyroid drugs
• Target TSH: 1.0-4.0 mIU/L 1
• Treatment recommended for subclinical hyperthyroidism in patients >65 years with TSH <0.1 mIU/L 2

Thyroid Storm (Emergency)

• Requires immediate treatment with:
  • Propylthiouracil or methimazole
  • Saturated solution of potassium iodide or sodium iodide
  • Dexamethasone
  • Beta-blockers (propranolol or esmolol for hemodynamic instability)
  • Supportive care (oxygen, antipyretics, monitoring) 1

Monitoring

• Regular thyroid function tests:

  • TSH and free T4
  • Adjust dose to maintain TSH within target range 1

• Monitor for complications:

  • Cardiovascular: Atrial fibrillation, heart failure
  • Bone health: Osteoporosis
  • Agranulocytosis: Complete blood count if fever, sore throat, or infection 4, 2

• Monitor for drug interactions:

  • Anticoagulants: Increased INR
  • Digitalis: Increased serum levels
  • Theophylline: Decreased clearance 4

Treatment Targets

• Low-risk patients: TSH 0.5-2.0 mIU/L
• Intermediate to high-risk patients: TSH 0.1-0.5 mIU/L
• Persistent disease: TSH <0.1 mIU/L
• Elderly patients: TSH 1.0-4.0 mIU/L 1

Pitfalls and Caveats

• Overtreatment with antithyroid drugs can cause hypothyroidism
• Undertreatment increases risk of cardiovascular complications and osteoporosis
• Methimazole side effects: Agranulocytosis, vasculitis, hypoprothrombinemia
• Pregnancy considerations: Risk of congenital malformations with methimazole in first trimester
• Drug interactions: Monitor patients on anticoagulants, beta-blockers, digitalis, or theophylline 1, 4