What is the treatment plan for subacute thyroiditis?

Treatment of Subacute Thyroiditis

For subacute thyroiditis, initiate beta-blockers (propranolol or atenolol) for symptomatic relief of thyrotoxic symptoms, and use corticosteroids (prednisone 40 mg daily tapered over 4-6 weeks) for moderate-to-severe neck pain, while monitoring thyroid function every 2-3 weeks to detect transition to hypothyroidism requiring levothyroxine replacement. 1, 2, 3

Initial Assessment and Monitoring

• Obtain baseline TSH, free T4, and inflammatory markers (ESR, CRP) at presentation 1
• Monitor thyroid function every 2-3 weeks during the initial phase to detect the transition from hyperthyroidism to hypothyroidism 1, 4
• T3 measurement can be helpful in highly symptomatic patients with minimal FT4 elevations 1

Management of the Thyrotoxic Phase

Beta-blocker therapy is the cornerstone for symptomatic hyperthyroidism:

• Use propranolol or atenolol for adrenergic symptoms including palpitations, tremors, anxiety, and fever 1, 4, 3
• Continue immune checkpoint inhibitor therapy if applicable, as thyroiditis rarely requires treatment interruption 5
• Provide hydration and supportive care 1
• If thyrotoxicosis persists beyond 6 weeks, refer to endocrinology for additional workup to rule out Graves' disease 1, 4

Pain Management Strategy

The choice between NSAIDs and corticosteroids depends on pain severity:

For Mild-to-Moderate Pain:

• NSAIDs (ibuprofen 1800 mg daily) can be attempted initially 6, 3
• However, NSAIDs have a 59.5% inadequate response rate, with 54% of patients requiring conversion to steroids within 9.5 days 6

For Moderate-to-Severe Pain (Preferred Approach):

• Prednisone 40 mg daily is the standard initial dose 2, 7
• Taper gradually over 4-6 weeks 8, 7
• Symptomatic remission typically occurs within 24-48 hours of steroid initiation 8, 7
• Short-term prednisone (30 mg daily for 1 week followed by NSAIDs) shows similar efficacy to 6-week courses with fewer side effects 8
• Lower initial doses (20 mg daily tapered over 4 weeks) are also effective, with 94% of patients achieving complete pain relief by 2 weeks 9

For Painful Thyroiditis Specifically:

• Consider prednisolone 0.5 mg/kg with taper if painful thyroiditis is present 5
• Withhold immune checkpoint inhibitors only if patient is severely unwell with symptomatic hyperthyroidism 5

Management of the Hypothyroid Phase

Levothyroxine replacement is indicated when hypothyroidism develops:

• Treat when TSH is elevated with low FT4, or when TSH >10 mIU/L even with normal FT4 5, 4
• For patients <70 years without cardiac disease or frailty: start full replacement at approximately 1.6 mcg/kg/day based on ideal body weight 1
• For patients >70 years or with cardiac comorbidities: start with 25-50 mcg daily 1
• In asymptomatic patients with elevated TSH but normal FT4 during recovery, consider monitoring for 3-4 weeks before treating to assess for spontaneous recovery 1
• If TSH becomes low on therapy, reduce or discontinue levothyroxine as this suggests overtreatment or recovery of thyroid function 1

Important Clinical Considerations

Steroid therapy provides significant advantages over NSAIDs:

• Permanent hypothyroidism develops in only 6.6% of steroid-treated patients versus 22.8% of NSAID-only patients 6
• NSAID-only treatment is an independent risk factor for permanent hypothyroidism (p=0.039) 6
• Positive anti-TPO antibodies are another risk factor for permanent hypothyroidism (p=0.029), making steroids particularly important in these patients 6
• Recurrence rates are higher with steroid-only therapy (23%) compared to NSAID-only therapy (10.5%), though overall recurrence is 19.8% 6

Common pitfalls to avoid:

• Missing the transition from hyperthyroidism to hypothyroidism due to inadequate monitoring 4
• Continuing levothyroxine when thyroid function recovers, leading to iatrogenic hyperthyroidism 1
• Using NSAIDs as first-line therapy in anti-TPO positive patients, increasing permanent hypothyroidism risk 6
• Failing to recognize that subacute thyroiditis is self-limited, with hyperthyroidism typically resolving within weeks 1

Long-Term Follow-Up

• Permanent hypothyroidism develops in <1% of patients overall but is more common with NSAID-only treatment 6, 7
• Recurrences occur in approximately 20% of patients and may require restoration of higher steroid doses 6, 7
• Thyroidectomy should be considered only in the very small minority with repeated relapses despite appropriate treatment 7