What is the treatment approach for a patient with thyroiditis, specifically Hashimoto's thyroiditis, De Quervain's thyroiditis, or radiation-induced thyroiditis?

Treatment of Thyroiditis

Treat thyroiditis with symptom-directed therapy: beta-blockers (propranolol 60-80 mg every 4-6 hours or atenolol) for the initial hyperthyroid phase, NSAIDs or corticosteroids for pain, and levothyroxine replacement when TSH exceeds 10 mIU/L or when symptomatic with TSH 4-10 mIU/L. 1, 2

Initial Phase: Managing Thyrotoxicosis

The hyperthyroid phase results from inflammatory release of preformed thyroid hormone, not increased synthesis, which is why antithyroid drugs are ineffective. 3, 4

Symptomatic Management:

• Beta-blockers are first-line for adrenergic symptoms (palpitations, tremors, anxiety, tachycardia) per American College of Cardiology recommendations 1
• Propranolol 60-80 mg orally every 4-6 hours or atenolol are preferred agents 1
• Target heart rate <100 bpm with continuous monitoring in severe cases 1
• Monitor thyroid function every 2-3 weeks during the thyrotoxic phase to catch the transition to hypothyroidism 1, 2

Critical caveat: Antithyroid medications (methimazole, propylthiouracil) have no role in typical thyroiditis since the thyroid is not actively producing excess hormone—it's simply leaking stored hormone from damaged follicles. 3, 4

Pain Management (Subacute/De Quervain's Thyroiditis)

For mild to moderate thyroid pain:

• NSAIDs are first-line therapy 1
• Salicylates can be used in mild cases 5

For severe pain or systemic symptoms:

• Systemic glucocorticoids are indicated for severe symptoms, high fever, or pain unresponsive to NSAIDs 1
• Prednisone 40 mg daily with gradual taper over several weeks typically provides relief within 24-48 hours 5
• Recurrences occur in a small percentage requiring dose restoration 5

Hypothyroid Phase Treatment

Indications for levothyroxine initiation:

• Start levothyroxine for any symptomatic patient with TSH elevation 1
• Start levothyroxine for asymptomatic patients with TSH >10 mIU/L 1, 2
• Consider treatment for TSH 4-10 mIU/L if symptomatic 2

Dosing strategy:

• For patients <70 years without cardiovascular disease: Start levothyroxine at 1.6 mcg/kg/day based on ideal body weight 1
• For patients >70 years or with cardiac disease: Start at 25-50 mcg/day and titrate gradually to avoid precipitating arrhythmias or angina 1
• Take on empty stomach, 30-60 minutes before breakfast with full glass of water 6
• Avoid concurrent administration with iron, calcium supplements, or antacids (separate by 4 hours) 6

Important FDA limitation: Levothyroxine is NOT indicated for treatment of hypothyroidism during the recovery phase of subacute thyroiditis, though this conflicts with clinical practice guidelines that support symptomatic treatment. 6 In real-world practice, temporary levothyroxine is commonly used and can be discontinued once thyroid function recovers. 1, 3

Monitoring and Adjustment

Frequency of monitoring:

• Every 2-3 weeks during thyrotoxic phase 1, 2
• Every 4-6 weeks initially during hypothyroid phase 1
• Reduce or discontinue levothyroxine if TSH becomes suppressed, suggesting overtreatment or recovery of thyroid function 1

When to refer to endocrinology:

• Thyrotoxic phase persisting beyond 6 weeks (consider Graves' disease) 1, 2
• Unusual presentations or difficulty titrating therapy 1
• Concern for central hypothyroidism 1
• Severe symptoms (Grade 3-4) affecting daily activities 2

Special Clinical Scenarios

Hashimoto's Thyroiditis:

• Typically presents with painless goiter and elevated thyroid peroxidase antibodies 3, 4
• Patients with overt hypothyroidism require lifelong levothyroxine therapy 3
• Treatment ameliorates hypothyroidism and may reduce goiter size 4

Postpartum Thyroiditis:

• Occurs within one year of delivery, miscarriage, or medical abortion 3, 4
• Monitor for thyroid function changes as many cases are transient 4
• Consider levothyroxine in women with TSH >10 mIU/L, or TSH 4-10 mIU/L who are symptomatic or desire fertility 4

Immunotherapy-Related Thyroiditis:

• ICI therapy can be continued in most cases, unlike other immune-related adverse events 1
• High-dose corticosteroids are rarely required for thyroid dysfunction 1
• Permanent hypothyroidism is more common than in other forms of thyroiditis 2

Thyroid Storm (Rare but Life-Threatening):

• Immediate treatment required: propranolol (or alternative beta-blocker), propylthiouracil or methimazole, potassium iodide, dexamethasone, and aggressive IV hydration (at least 2L normal saline initially) 1

Prognosis and Long-Term Considerations

• Most forms of thyroiditis are self-limited and resolve completely within 6-12 months 7, 5
• Less than 1% develop permanent hypothyroidism in subacute thyroiditis 5
• Hashimoto's thyroiditis typically requires lifelong replacement 3
• Surveillance and clinical follow-up are recommended in all cases to monitor for changes in thyroid function 3