What are the treatment options for hyperthyroidism?

Treatment Options for Hyperthyroidism

The first-line treatment for hyperthyroidism is thioamide medication (methimazole or propylthiouracil), with methimazole being the preferred option due to its superior efficacy, once-daily dosing, and better side effect profile. 1, 2

Primary Treatment Options

1. Antithyroid Medications

• Methimazole (MMI):

  • Drug of choice for most patients 3
  • More effective than propylthiouracil at normalizing thyroid hormone levels 4, 5
  • Recommended dosing:
    • Mild to moderate hyperthyroidism: 15 mg once daily
    • Severe hyperthyroidism: 30 mg once daily 6
  • Advantages: longer half-life, once-daily dosing, fewer severe side effects

• Propylthiouracil (PTU):

  • Second-line option
  • Preferred in first trimester of pregnancy and thyroid storm
  • Less effective than MMI at equivalent doses 4, 5
  • Typical dose: 150-300 mg daily (often divided)

2. Radioactive Iodine (I-131)

• Definitive treatment that destroys thyroid tissue
• Particularly effective for toxic nodular goiter 2
• Contraindicated in pregnancy 1
• Patients should not breastfeed for four months after treatment 1
• May exacerbate Graves' eye disease

3. Thyroidectomy

• Surgical removal of part or all of the thyroid gland
• Indicated when:
  • Patients do not respond to thioamide therapy
  • Large goiters causing compressive symptoms
  • Suspicious nodules
  • Patient preference for definitive treatment

Adjunctive Treatments

• Beta-blockers (e.g., propranolol):

  • Control symptoms (tachycardia, tremor, anxiety) while waiting for antithyroid drugs to take effect 1
  • Do not affect thyroid hormone levels

• Iodine preparations:

  • Used short-term to rapidly reduce thyroid hormone release
  • Primarily for thyroid storm or pre-surgical preparation

Treatment Algorithm Based on Etiology

Graves' Disease (70% of cases) 2

1. Initial treatment: Methimazole (15-30 mg daily based on severity)
2. Duration: 12-18 months (standard course) or 5-10 years (long-term approach with fewer recurrences)
3. Alternative options if medication fails or is contraindicated:
   • Radioactive iodine
   • Thyroidectomy

Toxic Nodular Goiter (16% of cases) 2

1. Preferred definitive treatments:
   • Radioactive iodine
   • Thyroidectomy
2. Medical therapy may be used temporarily or in those who cannot undergo definitive treatment

Thyroiditis (3% of cases) 2

1. Observation - often self-limiting
2. Symptomatic treatment with beta-blockers
3. Steroids for severe cases

Monitoring and Follow-up

• Check free T4 or free T4 index every 2-4 weeks initially 1
• Goal: Maintain free T4 or free T4 index in high-normal range using lowest possible thioamide dosage
• Once stable, monitoring can be less frequent

Important Considerations and Pitfalls

Side Effects of Antithyroid Drugs

• Agranulocytosis: Presents with sore throat and fever; requires immediate discontinuation and CBC 1
• Other adverse effects: Hepatitis, vasculitis, thrombocytopenia, rash
• PTU has higher rates of hepatotoxicity compared to MMI 6

Special Populations

Pregnancy

• PTU preferred in first trimester due to lower risk of birth defects
• Can switch to MMI after first trimester
• Goal: Use lowest effective dose to maintain free T4 in high-normal range
• I-131 absolutely contraindicated 1

Breastfeeding

• Both MMI and PTU compatible with breastfeeding 1

Thyroid Storm

• Medical emergency requiring intensive care
• Treatment includes high-dose antithyroid drugs, beta-blockers, iodine, and supportive care

Long-term Outcomes

• Recurrence after antithyroid drug discontinuation occurs in approximately 50% of Graves' disease patients 2
• Risk factors for recurrence: age <40 years, high initial free T4 levels, high antibody levels, large goiter 2
• Hyperthyroidism is associated with increased mortality if not adequately controlled 2

The choice between treatment options should be based on the specific cause of hyperthyroidism, disease severity, patient age, comorbidities, and pregnancy status, with the goal of rapidly achieving and maintaining euthyroidism to improve morbidity, mortality, and quality of life outcomes.