How is Hashimoto's thyroiditis managed?

Management of Hashimoto's Thyroiditis

Hashimoto's thyroiditis should be managed with thyroid hormone replacement therapy (levothyroxine) when hypothyroidism develops, with dosing typically ranging from 1.4 to 1.8 mcg/kg/day based on the degree of preserved thyroid functionality and lean body mass. 1

Diagnosis and Evaluation

• Diagnosis is based on:

  • Elevated thyroid peroxidase antibodies (TPOAbs)
  • Thyroid function tests (TSH, free T4)
  • Thyroid ultrasound showing characteristic changes
  • Fine needle aspiration biopsy when indicated

• Clinical presentation may include:

  1. Thyrotoxicosis phase (Hashitoxicosis) - when stored thyroid hormones are released from destroyed follicles
  2. Euthyroid phase - when preserved thyroid tissue compensates for destroyed thyrocytes
  3. Hypothyroid phase - when thyroid hormone production becomes insufficient 1

Treatment Algorithm Based on Thyroid Function

1. Euthyroid Hashimoto's Thyroiditis

• Monitor thyroid function (TSH, free T4) every 6-12 months
• No levothyroxine treatment is required if thyroid function is normal
• Some evidence suggests prophylactic levothyroxine may reduce antibody levels and lymphocytic infiltration, but this remains controversial 2
• The long-term clinical benefit of prophylactic therapy in euthyroid patients is not established 2

2. Hypothyroid Hashimoto's Thyroiditis

• Initiate levothyroxine replacement therapy:

  • Typical starting dose: 1.4-1.8 mcg/kg/day based on lean body mass 1, 3
  • Lower starting dose (25-50 mcg/day) for elderly patients, those with cardiac disease, or multiple comorbidities 4
  • Target TSH within normal reference range

• Monitoring:

  • Check TSH and free T4 levels 4-6 weeks after starting therapy
  • Make dose adjustments in 12.5-25 mcg increments if TSH remains elevated
  • Once stable, check levels every 6-12 months or if symptoms change 4

• Administration guidance:

  • Take levothyroxine as a single daily dose
  • On an empty stomach, 30-60 minutes before breakfast
  • With a full glass of water
  • Avoid medications that interfere with absorption (calcium, iron supplements, antacids) 4

3. Hashitoxicosis (Transient Thyrotoxicosis)

• Manage symptoms with beta-blockers (e.g., atenolol or propranolol) 5, 6
• Monitor thyroid function every 2-3 weeks to detect transition to hypothyroidism
• This phase is typically self-limited and resolves within weeks 5, 6

Special Considerations

Pregnancy

• Maintain TSH within trimester-specific reference ranges
• Target TSH below 2.5 mIU/L for the first trimester
• Increase levothyroxine dosage as needed during pregnancy (often by 30% or more)
• Use only levothyroxine (not T3 combinations) as T3 does not sufficiently cross the fetal blood-brain barrier 4, 1
• The presence of TPOAbs is associated with a 2-4 fold increase in risk of recurrent miscarriages and preterm birth 1

Elderly Patients

• Start with lower doses (25-50 mcg/day) and titrate slowly
• May tolerate slightly higher TSH levels (up to 7.5 mIU/L for patients over 80) 4
• Monitor for cardiac complications with excessive dosing

Monitoring for Complications

• Hashimoto's thyroiditis is associated with:
  • 1.6 times higher risk of papillary thyroid cancer
  • 60 times higher risk of thyroid lymphoma than the general population 1
• Monitor for thyroid nodules and changes in thyroid size/texture
• Consider ultrasound surveillance in long-standing disease

Treatment Pitfalls to Avoid

1. Overtreatment with levothyroxine can lead to:

   • Subclinical hyperthyroidism
   • Increased risk of atrial fibrillation in older adults
   • Decreased bone mineral density and increased fracture risk in postmenopausal women 4

2. Inadequate monitoring during therapy adjustment

3. Failure to recognize the triphasic pattern of thyroid dysfunction in some patients

4. Ignoring medication interactions that affect levothyroxine absorption

By following this approach, most patients with Hashimoto's thyroiditis can achieve optimal thyroid function and symptom control with appropriate monitoring and management.