What is the recommended treatment for Hashimoto's thyroiditis?

Treatment of Hashimoto's Thyroiditis

The recommended treatment for Hashimoto's thyroiditis with overt hypothyroidism is lifelong levothyroxine (T4) replacement therapy, typically at a dose of 1.6 mcg/kg/day for young, healthy adults, with lower starting doses for elderly patients or those with cardiac disease. 1, 2, 3

Diagnosis and Initial Assessment

• Hashimoto's thyroiditis is an autoimmune disorder characterized by:
  • Elevated thyroid peroxidase (TPO) antibodies
  • Hypothyroidism (elevated TSH with normal or low free T4)
  • Often presents with a painless goiter
  • May have symptoms of hypothyroidism (fatigue, cold intolerance, weight gain, constipation)

Treatment Algorithm

For Overt Hypothyroidism (Elevated TSH with Low Free T4):

1. Initiate levothyroxine therapy:

   • Young, healthy adults without cardiac disease: 1.6 mcg/kg/day 2
   • Elderly patients (>70 years) or those with cardiac disease: Start with lower dose (25-50 mcg/day) and titrate gradually 1

2. Monitoring and dose adjustment:

   • Check TSH and free T4 levels 6-8 weeks after starting therapy or dose adjustment 2
   • Adjust dose by 12.5-25 mcg increments if TSH remains above reference range 1
   • Goal: Maintain TSH within normal reference range (0.5-4.5 mIU/L) 2
   • Once stable, monitor every 6-12 months 2

For Subclinical Hypothyroidism (Elevated TSH with Normal Free T4):

1. TSH 4.5-10 mIU/L and asymptomatic:

   • Consider treatment based on individual factors (age, symptoms, cardiovascular risk)
   • Monitor TSH every 6-12 months if not treating 1

2. TSH persistently >10 mIU/L or symptomatic:

   • Initiate levothyroxine therapy as above 1

Special Considerations

• Medication administration:

  • Take levothyroxine on an empty stomach, 30-60 minutes before breakfast
  • Avoid taking with calcium supplements, iron supplements, antacids, and other medications that can interfere with absorption 2

• Pregnancy:

  • Increased levothyroxine requirements (by 30% or more) by 4-6 weeks' gestation 2
  • More frequent monitoring during pregnancy
  • Inadequate treatment increases risk of preeclampsia, preterm birth, and cognitive impairment in children 2

• Thyroiditis phases:

  • Some patients may initially present with a hyperthyroid phase (thyrotoxicosis) before developing hypothyroidism 3
  • During thyrotoxic phase, beta-blockers can be used for symptomatic relief 1

Medication Interactions

• Many medications can affect levothyroxine absorption or metabolism:
  • Calcium and iron supplements
  • Proton pump inhibitors
  • Bile acid sequestrants
  • Antacids 2

Prognosis and Long-term Management

• Hashimoto's thyroiditis typically requires lifelong thyroid hormone replacement 3
• The required dose may differ from other causes of hypothyroidism, with Hashimoto's patients typically requiring around 1.59 mcg/kg/day 4
• Regular monitoring is essential to ensure adequate replacement and avoid over-treatment

Common Pitfalls to Avoid

1. Inadequate monitoring: Failure to check thyroid function 6-8 weeks after dose adjustments
2. Overtreatment: Excessive levothyroxine can cause iatrogenic hyperthyroidism with increased risk of atrial fibrillation and bone loss 2
3. Medication interactions: Not accounting for medications that affect levothyroxine absorption
4. Inconsistent administration: Taking levothyroxine with food or inconsistently can lead to variable absorption 2
5. Failure to adjust dose during pregnancy: Requirements typically increase during pregnancy 2

Hashimoto's thyroiditis is the most common cause of hypothyroidism in iodine-sufficient areas, and proper treatment with appropriate levothyroxine dosing and regular monitoring is essential for optimal patient outcomes.