How should thyroiditis be evaluated and managed?

Evaluation and Management of Thyroiditis

Initial Evaluation

Thyroiditis evaluation begins with determining the clinical presentation pattern: presence or absence of thyroid pain, current thyroid function status, and temporal relationship to potential triggers (pregnancy, medications, viral illness). 1, 2

Key Clinical Features to Assess

• Pain and tenderness: Presence indicates subacute granulomatous thyroiditis or acute suppurative thyroiditis; absence suggests Hashimoto's, postpartum, or drug-induced thyroiditis 2, 3
• Timing: Onset within one year of delivery, miscarriage, or medical abortion indicates postpartum thyroiditis 1, 2
• Medication history: Recent initiation of amiodarone, immune checkpoint inhibitors, interleukin-2, interferon-alfa, lithium, or tyrosine kinase inhibitors suggests drug-induced thyroiditis 1, 3
• Preceding illness: Upper respiratory viral symptoms before thyroid dysfunction suggests subacute granulomatous thyroiditis 2

Diagnostic Testing

• Measure TSH and free T4 to determine current thyroid function status 1, 2
• Thyroid peroxidase antibodies (TPO): Elevated levels confirm Hashimoto thyroiditis 1, 2
• TSH receptor antibodies (TRAb) or thyroid stimulating immunoglobulin (TSI): Presence indicates Graves' disease rather than thyroiditis; absence supports thyroiditis diagnosis 4
• Radioactive iodine uptake scan: Low or absent uptake confirms thyroiditis; high uptake indicates Graves' disease 4, 2, 3
• Ultrasound: Provides supportive information but cannot definitively distinguish between conditions 4

Management by Clinical Scenario

Hyperthyroid (Thyrotoxic) Phase

Beta-blockers are the cornerstone of symptomatic management during the thyrotoxic phase; antithyroid drugs (methimazole, propylthiouracil) are ineffective for thyroiditis-related thyrotoxicosis and should be avoided except in thyroid storm emergencies. 5, 4

• Preferred agent: Propranolol 60-80 mg orally every 4-6 hours, or atenolol as alternative 5
• Rationale: Non-selective beta-blockers with alpha-blocking activity provide superior symptom control 5
• Monitoring frequency: Check TSH and free T4 every 2-3 weeks during thyrotoxic phase to detect transition to hypothyroidism 5, 1
• Expected duration: Thyrotoxic phase typically lasts approximately 1 month 5

Critical pitfall: Do not prescribe methimazole or propylthiouracil for thyroiditis-related thyrotoxicosis, as thyroid hormone is being released from damaged cells rather than newly synthesized 5, 4

Hypothyroid Phase

Initiate levothyroxine immediately when hypothyroidism develops in symptomatic patients with any TSH elevation, or in asymptomatic patients with TSH >10 mIU/L. 5

Dosing Strategy

• Patients <70 years without cardiovascular disease: Start levothyroxine at 1.6 mcg/kg/day based on ideal body weight 5
• Patients >70 years or with cardiac disease: Start at 25-50 mcg/day and titrate gradually to avoid precipitating arrhythmias or angina 5
• Adjustment: Titrate every 4 weeks until TSH is stable 6

Critical pitfall: Before starting levothyroxine, rule out adrenal insufficiency (especially in patients with suspected hypophysitis or central hypothyroidism), as thyroid hormone replacement can precipitate adrenal crisis 5, 4

Pain Management (Subacute Thyroiditis)

• First-line: NSAIDs for mild to moderate thyroid pain and tenderness 5, 2
• Second-line: Systemic glucocorticoids for severe symptoms, high fever, or pain unresponsive to NSAIDs 5

Hashimoto Thyroiditis

Patients with Hashimoto thyroiditis and overt hypothyroidism require lifelong thyroid hormone therapy with levothyroxine. 1, 2

• Diagnosis: Elevated TPO antibodies with or without goiter, typically presenting with hypothyroidism 1, 2
• Treatment goal: Normalize TSH and ameliorate hypothyroidism 2
• Additional benefit: May reduce goiter size 2

Postpartum Thyroiditis

Monitor thyroid function closely, as postpartum thyroiditis follows a triphasic pattern with potential for permanent hypothyroidism. 6, 1

• Hyperthyroid phase: Beta-blockers for symptomatic relief 2
• Hypothyroid phase: Consider levothyroxine if TSH >10 mIU/L, or if TSH 4-10 mIU/L with symptoms or fertility concerns 2
• Monitoring: TSH and free T4 levels should be evaluated in women who develop goiter during pregnancy or postpartum, or who develop symptoms 6
• Risk stratification: Greatest risk of permanent hypothyroidism occurs in women with highest TSH levels and antithyroid peroxidase antibodies 6

Immune Checkpoint Inhibitor-Associated Thyroiditis

ICI therapy can be continued in most cases of thyroiditis, unlike other immune-related adverse events; high-dose corticosteroids are rarely required. 5

• Monitoring schedule: Every 4-6 weeks initially, then each treatment cycle for first 3 months, thereafter every second cycle 5
• Thyrotoxic phase: Averages 1 month after ICI initiation; manage with beta-blockers 5
• Hypothyroid phase: Usually follows 1 month after thyrotoxic phase (approximately 2 months after ICI start); initiate levothyroxine immediately 5
• Endocrinology referral: Indicated if thyrotoxic phase persists >6 weeks, suspected hypophysitis, or complex presentations 5

Thyroid Storm

Thyroid storm is a life-threatening emergency requiring immediate treatment without waiting for confirmatory laboratory results. 6

Diagnostic Features

• Fever with tachycardia out of proportion to fever 6
• Altered mental status (nervousness, restlessness, confusion, seizures) 6
• Vomiting, diarrhea, cardiac arrhythmia 6
• Identifiable inciting event (surgery, infection, labor, delivery) 6

Treatment Protocol

• Propranolol (or alternative beta-blocker) targeting heart rate <100 bpm with continuous cardiac monitoring 5
• Propylthiouracil or methimazole 6
• Potassium iodide (or sodium iodide, Lugol's solution, or lithium as alternatives) 6
• Dexamethasone 6
• Aggressive IV hydration: At least 2L normal saline initially 5
• Phenobarbital 6
• General supportive measures: Oxygen, antipyretics, appropriate monitoring 6
• Treat underlying cause 6

Ongoing Surveillance

All patients with thyroiditis require clinical follow-up to monitor for changes in thyroid function, as the natural history includes potential progression to permanent hypothyroidism. 1

• During active phase: Monitor TSH and free T4 every 2-3 weeks 5, 1
• After stabilization: Continue periodic monitoring as thyroid function may evolve over time 1, 3
• Levothyroxine adjustment: Reduce or discontinue if TSH becomes suppressed, suggesting overtreatment or recovery of thyroid function 5

Indications for Endocrinology Referral

• Suspected or confirmed hypophysitis 5
• Complex primary hypothyroidism 5
• Persistent thyrotoxicosis >6 weeks 5
• Unusual presentations or difficulty titrating therapy 5
• Need for additional specialized testing (TRAb, TSI, radioactive iodine uptake) 5
• Grade 3-4 severe or life-threatening thyrotoxicosis 4