What is the management approach for Lymphocytic (Hashimoto's) thyroiditis?

Management of Lymphocytic (Hashimoto's) Thyroiditis

Treat all patients with overt hypothyroidism or symptomatic disease with levothyroxine replacement, starting at 1.6 mcg/kg/day in younger patients without cardiac disease, or 25-50 mcg/day in elderly or cardiac patients with gradual titration. 1

Initial Assessment and Diagnosis

• Confirm diagnosis by measuring thyroid peroxidase (TPO) antibodies, which are typically elevated in Hashimoto's thyroiditis 2
• Assess thyroid function with TSH and free T4 to determine the degree of hypothyroidism 1
• Evaluate for goiter on physical examination, as patients commonly present with nontender thyroid enlargement 2

Treatment Strategy Based on Thyroid Function

Overt Hypothyroidism (Elevated TSH with Low Free T4)

• Start levothyroxine replacement immediately 1
• For patients under 70 years without cardiovascular disease: initiate full replacement at 1.6 mcg/kg/day based on ideal body weight 1
• For patients over 70 years or with cardiac disease: start low at 25-50 mcg/day and titrate gradually to avoid cardiac complications 1
• Monitor TSH every 4-6 weeks initially until levels stabilize in the normal range 1

Subclinical Hypothyroidism (TSH 4-10 mIU/L with Normal Free T4)

• Consider levothyroxine treatment if: the patient is symptomatic, desires fertility, or has progressive symptoms 1
• Monitor without treatment in asymptomatic patients, but watch for progression to overt hypothyroidism 1

Severe Subclinical Hypothyroidism (TSH >10 mIU/L)

• Initiate levothyroxine treatment even if free T4 is normal, as progression to overt hypothyroidism is likely 1

Special Considerations

Postpartum Presentation

• Recognize that Hashimoto's thyroiditis can present with transient hyperthyroidism in the postpartum period before progressing to hypothyroidism 3
• Monitor thyroid function closely during and after pregnancy, as immune changes can unmask or modify the disease 3
• Treat postpartum hyperthyroid phase with beta-blockers for symptom control if needed 1

Monitoring and Dose Adjustment

• Reduce or discontinue levothyroxine if TSH becomes suppressed, as this indicates overtreatment or spontaneous recovery of thyroid function 1
• Continue monitoring long-term, as hypothyroidism is typically permanent but can fluctuate 2
• Levothyroxine treatment may reduce goiter size over time in addition to correcting hypothyroidism 2

Critical Pitfalls to Avoid

• Never start high-dose levothyroxine in elderly patients or those with cardiac disease without gradual titration, as this can precipitate cardiac events 1
• Do not overlook the transition from hyperthyroidism to hypothyroidism in postpartum or atypical presentations 3
• Avoid continuing levothyroxine at full replacement doses if TSH becomes suppressed, as this causes iatrogenic hyperthyroidism 1

When to Refer to Endocrinology

• Consult endocrinology for: unusual presentations, difficulty titrating therapy to target TSH, concern for central hypothyroidism, or recurrent hyperthyroid episodes 1
• Consider specialist input if the patient has coexisting autoimmune conditions or complex medication interactions 1