What is the initial treatment for Hashimoto's (Hashimoto's thyroiditis) thyroiditis?

Treatment of Hashimoto's Thyroiditis

Levothyroxine (T4) replacement therapy is the initial treatment of choice for Hashimoto's thyroiditis, with dosing based on patient age and comorbidities. 1

Diagnosis and Initial Assessment

• Hashimoto's thyroiditis is an autoimmune disorder characterized by:
  • Elevated thyroid peroxidase (TPO) antibodies
  • Hypothyroidism (elevated TSH, low free T4)
  • Often presents with a painless goiter
  • Hypoechogenicity on thyroid ultrasound

Treatment Algorithm

Initial Levothyroxine Dosing

• For patients under 70 years without cardiac disease:

  • Start at 1.6 mcg/kg/day
  • Target TSH range: 0.5-2.0 mIU/L 1

• For elderly patients (>70 years) or those with cardiac conditions:

  • Start at lower dose of 25-50 mcg/day
  • Target TSH range: 1.0-4.0 mIU/L
  • More conservative approach to avoid complications 1

• For pregnant women or those planning pregnancy:

  • More aggressive management with target TSH <2.5 mIU/L
  • Adjust dose to maintain trimester-specific TSH reference range 1

Monitoring and Dose Adjustment

1. Check thyroid function (TSH and free T4) 4-6 weeks after starting therapy
2. Adjust dose to maintain TSH within target range
3. Once stable, monitor every 6-12 months
4. For pregnant patients, monitor TSH every 4 weeks until stable 1

Clinical Considerations

Benefits of Treatment

• Alleviates symptoms of hypothyroidism
• Reduces goiter size
• Prevents progression of hypothyroidism
• Reduces cardiovascular risk associated with untreated hypothyroidism 1, 2

Treatment Response

• Most patients require lifelong therapy
• In approximately 20% of patients, thyroid function may recover, but this is difficult to predict 3
• TPO antibody levels typically decline during levothyroxine treatment (average 45% reduction after 1 year, 70% after 5 years), but become negative in only about 16% of patients 4

Common Pitfalls and Considerations

1. Medication Interactions:

   • Many medications can affect levothyroxine absorption and efficacy:
     • Take levothyroxine at least 4 hours apart from calcium, iron supplements, and antacids
     • Proton pump inhibitors may reduce absorption
     • Certain medications (phenobarbital, rifampin) may increase hepatic metabolism 5

2. Inadequate Response to Treatment:

   • If TSH remains elevated despite adequate replacement dose, consider:
     • Poor medication compliance
     • Malabsorption issues
     • Drug interactions
     • Need for dose adjustment 1

3. Overtreatment Risks:

   • Excessive levothyroxine can increase risk of:
     • Atrial fibrillation
     • Osteoporosis (particularly in elderly patients)
     • Low TSH on therapy suggests overtreatment; dose should be reduced 1

4. Special Populations:

   • Elderly patients (>80-85 years): Treatment decisions should be individualized, with consideration of avoiding treatment in the oldest patients with subclinical hypothyroidism 1
   • Patients with diabetes: Monitor glycemic control closely when starting or adjusting thyroid therapy 5
   • Patients on anticoagulants: Levothyroxine increases response to oral anticoagulants; monitor coagulation tests and adjust anticoagulant dose accordingly 5

By following this treatment approach, most patients with Hashimoto's thyroiditis can achieve normal thyroid function and improved quality of life with appropriate levothyroxine replacement therapy.