What are the initial treatment recommendations for Graves' disease and Hashimoto thyroiditis?

Initial Treatment Recommendations for Graves' Disease and Hashimoto Thyroiditis

Graves' Disease Treatment

For Graves' disease, methimazole is the first-line treatment (30 mg/day for severe hyperthyroidism, 15 mg/day for mild to moderate cases), with propylthiouracil reserved only for patients intolerant to methimazole or during the first trimester of pregnancy. 1, 2, 3

Treatment Algorithm for Graves' Disease:

1. Initial Management:

   • Start beta-blockers (e.g., propranolol) to control adrenergic symptoms 1
   • Initiate antithyroid medication:
     • Methimazole (MMI): First-line option 1, 2
       • Severe hyperthyroidism (FT4 ≥ 7 ng/dl): 30 mg/day 1, 4
       • Mild to moderate hyperthyroidism (FT4 < 7 ng/dl): 15 mg/day 1, 4
     • Propylthiouracil (PTU): Reserved for 1, 3:
       • Patients intolerant to methimazole
       • First trimester of pregnancy
       • Thyroid storm (emergency situation)

2. Monitoring and Dose Adjustment:

   • Measure T4 and T3 levels every 2-4 weeks initially 1
   • Adjust dose to maintain T4 in high-normal range 1
   • Monitor for adverse effects:
     • Agranulocytosis, hepatitis, vasculitis, thrombocytopenia 1
     • Discontinue medication if fever or sore throat appears 1
     • Higher risk of adverse events with higher MMI doses (50% with ≥0.7 mg/kg/day vs 20% with <0.7 mg/kg/day) 5

3. Treatment Duration:

   • Typical duration: 12-18 months 1
   • Goal: Use minimum effective dose 1
   • Remission occurs in approximately 50% of patients after 12-18 months 1

Special Considerations for Graves' Disease:

• Pregnancy: Monitor for fetal/neonatal thyroid dysfunction 1

  • First trimester: Use propylthiouracil
  • Second and third trimesters: Switch to methimazole

• Thyroid Storm: Emergency requiring immediate treatment with 1:

  • Propylthiouracil
  • Beta-blockers
  • Corticosteroids
  • Supportive measures

• Alternative Treatments (when antithyroid drugs are not appropriate): 1

  • Radioactive iodine (RAI) therapy: Results in permanent hypothyroidism requiring lifelong levothyroxine; may worsen thyroid eye disease in 15-20% of patients
  • Surgery (near-total thyroidectomy): Preferred for large goiters, suspicious nodules, moderate-severe thyroid eye disease, or coexisting hyperparathyroidism

Hashimoto's Thyroiditis Treatment

For Hashimoto's thyroiditis, levothyroxine is the treatment of choice when hypothyroidism develops, with initial dosing of 1.5 μg/kg daily for standard adults and 25-50 mcg daily for elderly or cardiac patients. 1

Treatment Algorithm for Hashimoto's Thyroiditis:

1. Monitoring Phase (for patients with preserved thyroid function):

   • Monitor thyroid function (TSH and free T4) every 6-12 months 1
   • Screen for other autoimmune conditions (celiac disease, pernicious anemia, diabetes) 1

2. Treatment Initiation (when hypothyroidism develops):

   • Levothyroxine: 1
     • Standard adults: 1.5 μg/kg daily
     • Elderly or cardiac patients: 25-50 mcg daily
     • Gradually increase as needed

3. Treatment Monitoring:

   • Check TSH and free T4 every 4-6 weeks until stable 1
   • Once stable, monitor every 6-12 months 1
   • Do not adjust dose based on antibody levels alone 1

Important Caveats and Pitfalls:

• For Graves' Disease:

  • MMI has better efficacy and safety profile than PTU for initial treatment 4, 6
  • PTU has higher rates of mild hepatotoxicity compared to MMI 4
  • Once-daily dosing of MMI improves adherence due to longer half-life 6
  • Neutropenia and rash can occur with both high and low doses of MMI 5

• For Hashimoto's Thyroiditis:

  • Do not treat based solely on the presence of antibodies without evidence of thyroid dysfunction 1
  • Patients may fluctuate between euthyroid and hypothyroid states, requiring careful monitoring 1

• Differential Diagnosis:

  • Thyroiditis: Transient hyperthyroidism, eventual hypothyroidism, decreased radioactive iodine uptake, negative anti-TSH receptor antibodies 1
  • Graves' Disease: Persistent hyperthyroidism, increased radioactive iodine uptake, positive anti-TSH receptor antibodies 1