How should I evaluate and manage a patient with suspected thyroiditis, including the appropriate laboratory workup and treatment for subacute (de Quervain), Hashimoto, postpartum, and silent thyroiditis?

Evaluation and Management of Thyroiditis

Initial Diagnostic Approach

Measure TSH, free T4, and free T3 to determine the phase of thyroid dysfunction, then obtain inflammatory markers (ESR, CRP) and thyroid peroxidase antibodies to distinguish between thyroiditis subtypes. 1, 2, 3

Laboratory Workup by Clinical Presentation

For patients with anterior neck pain:

• Check TSH, free T4, free T3, ESR, and CRP to diagnose subacute (de Quervain) thyroiditis 4, 5, 6
• ESR is typically markedly elevated (>50 mm/hr) in subacute granulomatous thyroiditis 7, 6
• Radioactive iodine uptake (RAIU) will be low (<5%) during the thyrotoxic phase 4, 7, 6

For patients presenting postpartum (within 12 months of delivery):

• Measure TSH, free T4, and anti-TPO antibodies to diagnose postpartum thyroiditis 1, 4
• RAIU is low during the hyperthyroid phase, distinguishing it from Graves' disease 4, 6
• Anti-TPO antibodies are positive in most cases and predict risk of permanent hypothyroidism 1, 4

For patients with painless goiter or hypothyroid symptoms:

• Check TSH, free T4, anti-TPO antibodies, and anti-thyroglobulin antibodies for Hashimoto thyroiditis 4, 7, 6
• Anti-TPO antibodies are elevated in Hashimoto thyroiditis and confirm autoimmune etiology 4, 7

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Management by Thyroiditis Type

Subacute (de Quervain) Thyroiditis

For mild to moderate symptoms, initiate NSAIDs (aspirin 650 mg every 4-6 hours or ibuprofen 600-800 mg three times daily) as first-line therapy. 5, 6, 8

For severe symptoms with marked pain, fever, or prostration, start prednisone 40 mg daily with rapid symptom relief expected within 24-48 hours, then taper gradually over 4-6 weeks. 5, 6

• Beta-blockers (propranolol 20-40 mg three times daily or atenolol 25-50 mg daily) control adrenergic symptoms during the thyrotoxic phase 1, 3, 4
• Monitor thyroid function every 2-3 weeks to detect transition to hypothyroidism 1, 3, 4
• Levothyroxine is indicated only if hypothyroid phase causes significant symptoms or TSH >10 mIU/L 2, 4, 5
• Recurrence occurs in <10% of patients; if symptoms return during steroid taper, increase prednisone dose temporarily 5, 6
• Permanent hypothyroidism develops in <1% of cases 5, 8

Hashimoto Thyroiditis

Initiate levothyroxine therapy immediately for patients with overt hypothyroidism (elevated TSH with low free T4), targeting TSH 0.5-4.5 mIU/L. 2, 4, 6

For subclinical hypothyroidism (TSH >10 mIU/L with normal free T4), start levothyroxine regardless of symptoms due to progression risk. 2, 4

• Start levothyroxine 1.6 mcg/kg/day in patients <70 years without cardiac disease 2
• Use 25-50 mcg/day initial dose in elderly patients or those with cardiac disease, titrating by 12.5-25 mcg every 6-8 weeks 2
• Lifelong thyroid hormone therapy is generally required 4, 6, 8
• Monitor TSH every 6-8 weeks during dose titration, then every 6-12 months once stable 2

Postpartum Thyroiditis

Treat the hyperthyroid phase with beta-blockers (propranolol 20-40 mg three times daily) for symptomatic relief; antithyroid drugs are contraindicated because this is destructive thyroiditis, not Graves' disease. 1, 4

For the hypothyroid phase, initiate levothyroxine if TSH >10 mIU/L or if symptomatic with any TSH elevation, as symptoms may significantly impair postpartum quality of life. 1, 4

• Monitor TSH and free T4 every 4-6 weeks during the first postpartum year 1
• Permanent hypothyroidism develops in 20-30% of women with postpartum thyroiditis 4, 7
• Women with highest TSH levels and anti-TPO antibodies have greatest risk of permanent hypothyroidism 1
• Recurrence risk is 70% in subsequent pregnancies 4

Silent (Painless) Thyroiditis

Manage identically to postpartum thyroiditis: beta-blockers for hyperthyroid symptoms, levothyroxine for symptomatic hypothyroidism, and close monitoring for spontaneous resolution. 4, 7, 6

• Silent thyroiditis is clinically indistinguishable from postpartum thyroiditis except it occurs outside the postpartum period 4, 7
• The triphasic pattern (thyrotoxicosis → hypothyroidism → recovery) typically resolves within 6-12 months 4, 7, 6
• RAIU is low during thyrotoxic phase, confirming destructive rather than hyperactive thyroid disease 4, 6

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Critical Management Principles Across All Types

Monitor thyroid function every 2-3 weeks during the acute phase to catch the transition from hyperthyroidism to hypothyroidism, which is the most common outcome for transient thyroiditis. 1, 3, 4

Never use antithyroid drugs (methimazole, propylthiouracil) for thyroiditis-induced thyrotoxicosis, as the mechanism is hormone release from damaged cells, not hormone overproduction. 4, 6

Distinguish thyroiditis from Graves' disease by checking RAIU: low uptake (<5%) indicates thyroiditis, while elevated uptake (>30%) indicates Graves' disease. 4, 7, 6

Common Pitfalls to Avoid

• Do not assume hyperthyroidism is permanent; most thyroiditis cases resolve spontaneously within weeks to months 4, 7, 5
• Do not discontinue levothyroxine prematurely in Hashimoto thyroiditis; most patients require lifelong therapy 4, 6
• Do not miss the hypothyroid phase by failing to monitor TSH regularly during recovery 1, 3, 4
• Do not treat subclinical hypothyroidism (TSH 4.5-10 mIU/L with normal free T4) in asymptomatic patients with transient thyroiditis; 30-60% normalize spontaneously 2
• Do not overlook drug-induced thyroiditis in patients taking amiodarone, immune checkpoint inhibitors, interferon-alfa, interleukin-2, lithium, or tyrosine kinase inhibitors 4, 6

Special Considerations

For patients on immune checkpoint inhibitors with thyroiditis, continue immunotherapy in most cases while managing thyroid dysfunction, as high-dose corticosteroids are rarely required for thyroid dysfunction alone. 1, 3

For pregnant or postpartum women with thyroid dysfunction, measure anti-TPO antibodies to predict risk of permanent hypothyroidism and guide long-term monitoring. 1, 4

For patients with severe subacute thyroiditis unresponsive to corticosteroids after multiple courses, consider thyroidectomy only as a last resort in the rare patient with repeated relapses. 5