What is the management of Hashimoto thyroiditis?

Management of Hashimoto Thyroiditis

Levothyroxine therapy is the primary treatment for Hashimoto thyroiditis when TSH levels exceed 10 mIU/L, while patients with TSH between 4.5-10 mIU/L should be monitored for 3-6 months before initiating treatment. 1

Diagnosis and Initial Assessment

• Laboratory Testing:

  • Measure both TSH and free T4 simultaneously for accurate diagnosis 1
  • Test for thyroid peroxidase (TPO) and thyroglobulin antibodies to confirm Hashimoto's 2
  • Multiple tests over 3-6 months are recommended to confirm abnormal findings 1

• Clinical Presentation: Hashimoto's may present in three phases 2:

  1. Thyrotoxicosis (Hashitoxicosis) - from release of stored hormones during thyroid destruction
  2. Euthyroidism - when preserved thyroid tissue compensates for damage
  3. Hypothyroidism - when thyroid hormone production becomes insufficient

Treatment Algorithm

1. For Overt Hypothyroidism (TSH >10 mIU/L)

• Start levothyroxine at 1.6 mcg/kg/day for patients under 70 without cardiac disease 1
• For elderly patients or those with cardiac conditions, start at lower dose of 25-50 mcg/day 1
• Target TSH range: 0.5-2.0 mIU/L for most patients; 1.0-4.0 mIU/L for elderly 1

2. For Subclinical Hypothyroidism (TSH 4.5-10 mIU/L)

• Monitor for 3-6 months before initiating treatment 1
• Consider treatment if symptomatic (fatigue, other hypothyroid symptoms) 1
• Consider treatment in pregnant women or those planning pregnancy 1, 3

3. For Hashitoxicosis (initial thyrotoxic phase)

• Treat symptoms with β-blockers until the phase resolves 4
• Non-dihydropyridine calcium channel antagonists (diltiazem or verapamil) are alternatives when beta-blockers cannot be used 1

4. For Euthyroid Hashimoto's

• Regular monitoring of thyroid function every 6-12 months 1, 5
• Some evidence suggests prophylactic levothyroxine may reduce antibody levels and prevent progression to hypothyroidism, but this is not standard practice 6

Monitoring and Follow-up

• After initiating treatment:

  • Monitor TSH and free T4 at 6-8 weeks after any dose change 1, 3
  • Once stable, evaluate every 6-12 months 3

• For untreated patients:

  • Monitor TSH and free T4 every 6-12 months 1
  • Watch for progression to hypothyroidism, which occurs in approximately 20% of initially euthyroid patients within 18 months 5

Special Populations

Pregnancy

• For pregnant patients with pre-existing hypothyroidism:
  • Measure TSH and free T4 as soon as pregnancy is confirmed and during each trimester 3
  • Target TSH within trimester-specific reference range 3
  • Increase dose by 12.5-25 mcg/day as needed 3
  • Monitor TSH every 4-8 weeks 1, 3
  • Use only levothyroxine (T3 does not adequately cross fetal blood-brain barrier) 2

Pediatric Patients

• For children and adolescents:
  • Start at one-fourth the recommended full replacement dosage 3
  • Increase weekly by one-fourth until full dose is reached 3
  • Monitor growth, development, and bone maturation regularly 3
  • Consider screening for other autoimmune conditions, particularly celiac disease 1

Important Considerations and Pitfalls

• Overtreatment risks:

  • Increased risk of atrial fibrillation (3-fold risk in adults ≥60 years with TSH ≤0.1 mIU/L) 1
  • Osteoporosis, particularly in elderly patients 1
  • Hyperactivity in pediatric patients 3

• Medication interactions:

  • Many medications can interfere with levothyroxine absorption
  • Take levothyroxine on an empty stomach, 30-60 minutes before breakfast

• Potential for recovery:

  • Approximately 20% of patients with hypothyroidism due to Hashimoto's may recover thyroid function 7
  • However, most patients require lifelong therapy 2

• Long-term monitoring:

  • Hashimoto's is associated with 1.6 times higher risk of papillary thyroid cancer and 60 times higher risk of thyroid lymphoma 2
  • Regular clinical evaluation is essential

Remember that levothyroxine has a narrow therapeutic index, and both overtreatment and undertreatment can have negative effects on multiple body systems 3.