Painful self-limited granulomatous thyroiditis after viral illness with classic triphasic course: thyrotoxicosis → hypothyroidism → recovery.
Also known as: subacute thyroiditis, de Quervain thyroiditis, granulomatous thyroiditis, giant cell thyroiditis, painful thyroiditis
Overview
Self-limited inflammatory disorder of the thyroid gland, typically following a viral upper respiratory infection, characterized by neck pain, tender goiter, systemic inflammation, and a triphasic clinical course of thyrotoxicosis followed by hypothyroidism followed by recovery to euthyroidism in the majority of patients.
Epidemiology
Annual incidence ~5 per 100,000. Peak age 40-50 years; female-to-male ratio approximately 4:1. Seasonal clustering in summer and fall corresponds with viral upper respiratory infections. Strong association with HLA-B*35 haplotype.
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HLA-B*35 haplotype (carried by approximately 70% of patients)
Female sex, middle age
Reported but rare association with COVID-19 and following COVID-19 vaccination
Pathophysiology
Viral infection (or postviral immune response) damages thyroid follicles, releasing preformed thyroid hormone (T4 and T3) and thyroglobulin into the circulation, producing transient thyrotoxicosis without increased hormone synthesis. Iodine uptake by remaining follicles is therefore suppressed (low radioactive iodine uptake distinguishes destructive thyrotoxicosis from Graves disease). Inflammation produces classic giant cell and granulomatous histology and a tender, firm goiter. Follicular depletion drives the hypothyroid phase as stored hormone is exhausted, followed by gradual recovery as follicles regenerate.
Clinical presentation
Symptoms
Neck pain — anterior, often radiating to jaw or ears; worse with swallowing or neck movement
No ophthalmopathy or dermopathy (helps distinguish from Graves disease)
Classic findings
Markedly tender, firm goiter in a middle-aged woman after a viral illness; ESR often >50-100 mm/hr; HLA-B*35 association.
Differential diagnosis
Graves disease — Painless diffuse goiter with bruit, ophthalmopathy, dermopathy; elevated TRAb; HIGH radioactive iodine uptake; diffuse uptake on scan
Painless (silent) thyroiditis — No pain, no fever, normal ESR; often postpartum; low radioactive iodine uptake (similar to subacute); thyroid peroxidase antibodies often present
Suppurative (acute) thyroiditis — Severe pain with marked overlying erythema, high fever, leukocytosis with left shift; usually unilateral; bacterial (Staph aureus, Strep); requires drainage and IV antibiotics; usually NORMAL thyroid function
Toxic nodular goiter — Painless, single or multiple hot nodules; elderly; focal uptake on scan with suppression of remaining gland
Hashimoto thyroiditis (Hashitoxicosis phase) — Painless firm goiter; high TPO antibodies; typically transient mild thyrotoxicosis before chronic hypothyroidism
Acute hemorrhage into a thyroid nodule — Sudden focal pain and swelling without systemic inflammation; ultrasound shows hemorrhagic cystic change; thyroid function usually normal
Iodine-induced (Jod-Basedow) or amiodarone thyroiditis — History of iodine exposure or amiodarone use; variable uptake; amiodarone type 1 vs type 2 distinction
Diagnostic workup
Diagnostic criteria
Clinical diagnosis based on the combination of anterior neck pain, tender goiter, elevated inflammatory markers (ESR >50 mm/hr), thyrotoxic biochemistry with suppressed TSH and elevated free T4, and low radioactive iodine uptake. Biopsy is rarely needed but shows characteristic multinucleated giant cells and granulomas.
Labs
TSH (suppressed in thyrotoxic phase, elevated in hypothyroid phase, normal in recovery)
Free T4 and free T3 (elevated initially; T4/T3 ratio higher than in Graves because of hormone leakage from gland storage rather than de novo synthesis)
Erythrocyte sedimentation rate (ESR) and C-reactive protein — markedly elevated, often ESR >50-100 mm/hr
Thyroglobulin — elevated (released during follicular destruction)
Mild leukocytosis or normal CBC
TPO and thyroglobulin antibodies usually negative or low; TRAb negative
Radioactive iodine uptake (RAIU) — LOW (typically <5%) in thyrotoxic phase — distinguishes destructive thyroiditis from Graves disease
Imaging
Thyroid ultrasound — heterogeneous, hypoechoic regions in the gland with decreased vascularity on color Doppler (helpful when radioactive iodine cannot be used, e.g., pregnancy, lactation)
24-hour radioactive iodine uptake scan — confirms low uptake when diagnosis is unclear or to differentiate from Graves disease
Triphasic course of subacute (de Quervain) thyroiditis.
Treatment
First-line
Nonsteroidal anti-inflammatory drugs — ibuprofen 400-800 mg every 6-8 hours, naproxen 500 mg twice daily, or high-dose aspirin — first-line for pain in mild-to-moderate disease
Beta-blocker for thyrotoxic symptoms — propranolol 20-40 mg every 6-8 hours, atenolol 25-50 mg daily, or metoprolol — controls tachycardia, tremor, anxiety; does not affect underlying inflammation
Reassurance and education about the self-limited triphasic course
Second-line / adjunct
Oral glucocorticoid — prednisone 40 mg daily for 1-2 weeks then taper over 4-6 weeks — for severe pain not responding to NSAIDs within 2-3 days, severe inflammation, or marked thyrotoxicosis
Levothyroxine — temporary replacement during a prolonged or symptomatic hypothyroid phase; usually weaned after several months to confirm recovery
Antithyroid drugs (methimazole, propylthiouracil) are NOT indicated — destructive thyroiditis releases preformed hormone and does not respond to drugs that block hormone synthesis
Complications
Permanent hypothyroidism in approximately 5-15% of patients, requiring lifelong levothyroxine
Recurrent subacute thyroiditis (~2% of cases, usually within 2 years)
Atrial fibrillation, particularly in older patients during the thyrotoxic phase
Adrenal insufficiency risk with abrupt glucocorticoid taper
Misdiagnosis as suppurative thyroiditis or thyroid cancer leading to unnecessary intervention
PANCE pearls
The combination of a TENDER goiter, markedly elevated ESR, and LOW radioactive iodine uptake essentially clinches subacute thyroiditis — Graves disease has none of these features.
Antithyroid drugs (methimazole, PTU) DO NOT WORK in subacute thyroiditis because there is no de novo hormone synthesis — the hormone has already been made and is being passively released from damaged follicles.
The classic triphasic course (thyrotoxicosis lasting 2-8 weeks, hypothyroidism lasting 2-8 weeks, recovery over months) is variable — about one-third of patients skip the hypothyroid phase entirely.
Steroids dramatically reduce pain within 24-72 hours and shorten the inflammatory phase but do not change the rate of permanent hypothyroidism — reserve for severe disease or NSAID failure.
Free T4-to-T3 ratio is typically higher in destructive thyroiditis (leakage of stored T4) than in Graves (preferential T3 synthesis) — useful clue in equivocal cases.
References
ATA 2016 — American Thyroid Association Guidelines for Diagnosis and Management of Hyperthyroidism and Other Causes of Thyrotoxicosis (Ross et al., Thyroid 2016)
AACE/ACE 2011 — American Association of Clinical Endocrinologists and American College of Endocrinology Clinical Practice Guidelines for Hyperthyroidism and Other Causes of Thyrotoxicosis (Bahn et al., Endocr Pract 2011)
ATA 2014 (hypothyroidism) — Guidelines for the Treatment of Hypothyroidism (Jonklaas et al., Thyroid 2014)
Fatourechi et al. 2003 — Clinical Features and Outcome of Subacute Thyroiditis in an Incidence Cohort (Fatourechi et al., J Clin Endocrinol Metab 2003)
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