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

Treatment of Autoimmune Thyroiditis (Hashimoto's Thyroiditis)

The primary treatment for Hashimoto's thyroiditis is levothyroxine replacement therapy when TSH becomes elevated, with observation and monitoring for euthyroid patients. 1, 2

Euthyroid Hashimoto's Thyroiditis (Normal Thyroid Function)

When NOT to Treat

• For euthyroid patients with positive thyroid antibodies but normal TSH and free T4, observation is recommended rather than immediate treatment. 1
• Levothyroxine is not indicated for treatment of hypothyroidism during the recovery phase of subacute thyroiditis. 2
• Starting treatment based solely on antibody levels without thyroid dysfunction leads to unnecessary risks of iatrogenic hyperthyroidism in 14-21% of patients, causing atrial fibrillation, osteoporosis, and fractures. 1

Monitoring Protocol for Euthyroid Patients

• Check TSH and free T4 every 4-6 weeks initially to establish baseline stability. 1
• Once stability is confirmed, extend monitoring to every 6-12 months. 1
• Patients with significantly elevated anti-TPO antibodies require more frequent monitoring due to higher progression risk (4.3% per year vs 2.6% in antibody-negative patients). 1, 3

When to Initiate Levothyroxine Treatment

Clear Indications for Treatment

Initiate levothyroxine when:

• TSH persistently >10 mIU/L, regardless of symptoms or free T4 level - this carries approximately 5% annual risk of progression to overt hypothyroidism. 1, 4
• TSH 4.5-10 mIU/L with symptoms of hypothyroidism (fatigue, weight gain, cold intolerance, constipation, dry skin, hair loss). 1, 5
• Any TSH elevation with low free T4 (overt hypothyroidism). 2, 6
• Pregnancy or planning pregnancy with any TSH elevation - subclinical hypothyroidism is associated with preeclampsia, low birth weight, and neurodevelopmental effects in offspring. 7, 2

Critical Pre-Treatment Safety Check

Before starting levothyroxine, always rule out concurrent adrenal insufficiency, especially in patients with multiple autoimmune conditions. Starting thyroid hormone before corticosteroids can precipitate life-threatening adrenal crisis. 1, 4

Levothyroxine Dosing Strategy

Initial Dosing

For patients <70 years without cardiac disease:

• Start with full replacement dose of approximately 1.6 mcg/kg/day. 1, 4
• This rapidly normalizes thyroid function and prevents cardiovascular dysfunction. 4

For patients >70 years OR with cardiac disease:

• Start with lower dose of 25-50 mcg/day. 1, 4, 2
• Titrate gradually every 6-8 weeks to avoid exacerbating cardiac symptoms. 4
• Elderly patients with coronary disease risk cardiac decompensation even with therapeutic doses. 4

For pregnant patients with pre-existing hypothyroidism:

• Increase pre-pregnancy dose by 25-50% as soon as pregnancy is confirmed. 2
• Levothyroxine requirements increase during early pregnancy for proper fetal neurologic development. 2

Dose Titration and Monitoring

• Recheck TSH and free T4 every 6-8 weeks after any dose adjustment - this represents the time needed to reach steady state. 1, 4, 2
• Adjust dose in increments of 12.5-25 mcg based on patient age and cardiac status. 4
• Target TSH within reference range of 0.5-4.5 mIU/L with normal free T4. 1, 4
• Once stable, monitor TSH every 6-12 months or when symptoms change. 1, 2

Managing Treatment Complications

Overtreatment (Iatrogenic Hyperthyroidism)

Approximately 25% of patients on levothyroxine are unintentionally maintained on excessive doses. 1, 4

If TSH <0.1 mIU/L:

• Reduce levothyroxine dose by 25-50 mcg immediately. 4
• Prolonged TSH suppression increases risk for atrial fibrillation (especially in elderly), osteoporosis, fractures, and cardiovascular mortality. 1, 4

If TSH 0.1-0.45 mIU/L:

• Reduce dose by 12.5-25 mcg, particularly in elderly patients or those with cardiac disease. 4

Undertreatment

If TSH remains elevated despite treatment:

• Confirm medication adherence and proper administration (take on empty stomach, 30-60 minutes before breakfast). 6
• Check for drug interactions (calcium, iron, proton pump inhibitors, bile acid sequestrants). 6
• Consider malabsorption issues. 6
• Increase dose by 12.5-25 mcg and recheck in 6-8 weeks. 4

Special Populations

Patients on Immune Checkpoint Inhibitors

• Thyroid dysfunction occurs in 6-20% of patients on anti-PD-1/PD-L1 therapy. 4
• Consider treatment even for subclinical hypothyroidism if fatigue or other symptoms are present. 4
• Monitor TSH every 4-6 weeks for first 3 months, then every second cycle. 4
• Continue immunotherapy in most cases - thyroid dysfunction rarely requires treatment interruption. 4

Patients with Cardiac Disease

• Start at 25-50 mcg/day maximum. 4, 2
• Titrate slowly with smaller increments (12.5 mcg). 4
• Monitor for angina, palpitations, dyspnea, or arrhythmias at each follow-up. 4
• Never start at full replacement dose - this can precipitate myocardial infarction or fatal arrhythmias. 4

Non-Pharmacologic Considerations

While levothyroxine is the cornerstone of treatment, attention should be paid to:

• Adequate calcium (1200 mg/day) and vitamin D (1000 units/day) intake to prevent bone demineralization, especially in patients with chronically suppressed TSH. 4
• Healthy lifestyle and appropriate supplementation of vitamins and microelements. 6
• Regular monitoring for thyroid gland enlargement and nodular goiter development. 6, 8

Critical Pitfalls to Avoid

• Never treat based on single elevated TSH value - 30-60% normalize on repeat testing. 1, 4
• Never start thyroid hormone before ruling out adrenal insufficiency in patients with suspected central hypothyroidism or multiple autoimmune conditions. 1, 4
• Never initiate treatment based solely on positive antibodies without thyroid dysfunction. 1
• Never adjust doses more frequently than every 6-8 weeks before reaching steady state. 4
• Never overlook medication interactions that impair levothyroxine absorption. 6

Surveillance for Malignant Transformation

A relationship between Hashimoto's thyroiditis and possible malignant transformation (particularly papillary thyroid cancer) has been proposed, though specific correlation remains debated. 7, 8 Regular monitoring for thyroid nodules and enlargement is essential. 6, 8