What is the recommended treatment for autoimmune thyroiditis?

Treatment of Autoimmune Thyroiditis

Thyroid hormone replacement therapy with levothyroxine is the recommended treatment for autoimmune thyroiditis when patients develop hypothyroidism, with dosing based on symptom severity and TSH levels. 1

Diagnosis and Evaluation

• Autoimmune thyroiditis (AIT) is characterized by an autoimmune process that destroys thyrocytes, leading to hormonal disorders and is the most common cause of hypothyroidism in the United States 1, 2
• Diagnosis requires measurement of TSH and Free T4 levels; positive anti-thyroid antibodies (thyroid peroxidase and thyroglobulin antibodies) support the diagnosis 1, 2
• Elevated TgAb (thyroglobulin antibodies) are significantly associated with symptom burden in patients with Hashimoto's thyroiditis, including fragile hair, facial edema, eye edema, and harsh voice 3
• The disease may progress through phases: initial hyperthyroidism (thyrotoxicosis) due to release of stored hormones, followed by euthyroidism, and eventually hypothyroidism as thyroid destruction continues 2, 4

Treatment Recommendations for Hypothyroidism

For Symptomatic Patients:

• Start levothyroxine therapy in all symptomatic patients with any degree of TSH elevation 1
• For asymptomatic patients with persistent TSH levels >10 mIU/L (measured 4 weeks apart), initiate levothyroxine therapy 1

Dosing Guidelines:

• For patients <70 years without cardiac disease or multiple comorbidities: Initial full replacement dose of approximately 1.6 mcg/kg/day based on ideal body weight 1
• For patients >70 years and/or those with cardiac disease or multiple comorbidities: Start with lower dose of 25-50 mcg/day and titrate gradually 1
• Patients with immune checkpoint inhibitor-associated thyroiditis may require higher doses (1.45 mcg/kg/day) compared to traditional Hashimoto's thyroiditis (1.25 mcg/kg/day) 5

Monitoring:

• Monitor TSH every 6-8 weeks while titrating hormone replacement to goal TSH within reference range 1
• FT4 can help interpret ongoing abnormal TSH levels during therapy, as TSH may take longer to normalize 1
• Once adequately treated, repeat testing every 6-12 months or as indicated for change in symptoms 1

Management Based on Severity

Mild Hypothyroidism (TSH >4.5 and <10 mIU/L, asymptomatic):

• Monitoring without immediate treatment is reasonable 1
• Check TSH (with option of FT4) every 4-6 weeks as part of routine monitoring 1

Moderate Hypothyroidism (TSH persistently >10 mIU/L or symptomatic):

• Prescribe thyroid hormone supplementation 1
• Consider endocrine consultation for unusual clinical presentations, concern for central hypothyroidism, or difficulty titrating hormone therapy 1

Severe Hypothyroidism (severe symptoms, medically significant):

• Endocrine consultation to assist with rapid hormone replacement 1
• Hospital admission for developing myxedema (bradycardia, hypothermia, and altered mental status) 1
• If uncertainty exists about primary vs. central hypothyroidism, hydrocortisone should be given before thyroid hormone is initiated 1

Management of Thyrotoxicosis Phase

• Beta-blockers (e.g., atenolol or propranolol) for symptomatic relief during the hyperthyroid phase 1
• Close monitoring of thyroid function every 2-3 weeks to detect transition to hypothyroidism 1
• For persistent thyrotoxicosis (>6 weeks), consider endocrine consultation for additional workup 1
• Thyroiditis is typically self-limited, with the hyperthyroid phase resolving in weeks with supportive care 1

Special Considerations

• Elevated TSH can be seen in the recovery phase of thyroiditis; in asymptomatic patients with normal FT4, monitoring before treating may be appropriate to determine if there is recovery within 3-4 weeks 1
• Development of low TSH on therapy suggests overtreatment or recovery of thyroid function; dose should be reduced or discontinued with close follow-up 1
• Certain medications can affect levothyroxine absorption or metabolism, including iron supplements, calcium, proton pump inhibitors, and enzyme inducers 6, 7
• Levothyroxine should be taken on an empty stomach to maximize absorption 7

Pitfalls to Avoid

• Avoid overtreatment with levothyroxine, which can lead to thyrotoxicosis symptoms (tachycardia, tremor, sweating) and increased risk of osteoporotic fractures and atrial fibrillation, especially in the elderly 7
• Don't attribute non-specific symptoms to slightly elevated TSH without confirming persistent elevation, as 30-60% of high TSH levels are not confirmed on a second blood test 7
• Recognize transient hypothyroidism, which may not require lifelong treatment 7
• When adjusting levothyroxine dose, wait 6-12 weeks before reassessment due to the long half-life of the medication 7