Subacute Granulomatous Thyroiditis

Aka: Subacute Granulomatous Thyroiditis, Granulomatous Thyroiditis, Giant Cell Thyroiditis, Subacute Thyroiditis, de Quervain's Thyroiditis, de Quervain Thyroiditis

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II. Definitions

  1. Subacute Granulomatous Thyroiditis
    1. Inflammatory, Painful Thyroiditis follows Viral Infection

III. Epidemiology

  1. Incidence: 5 per 100,000 persons
    1. Most common cause of Painful Thyroiditis
  2. Peak Incidence between ages 40 to 50 years
  3. More common in women by 4 fold
  4. Peak onset in late summer and early fall months

IV. Pathophysiology

  1. Associated with HLA-B35
  2. Thyroiditis associated with Viral Infection
    1. Coxsackievirus
    2. Echovirus
    3. Epstein Barr Virus
    4. Adenovirus
    5. Influenza
    6. Covid19 (SARS-CoV2)
  3. Activated T-Lymphocytes injure Thyroid follicular cells (destructive Thyroiditis)
    1. Results in the initial T4 and T3 unbridled increase
    2. Ultimately T4 and T3 falls when stores are exhausted

V. Symptoms

  1. Upper Respiratory Infection within prior 30 days (recalled by 25% of patients)
  2. Prodrome
    1. Myalgias
    2. Low-grade fever
    3. Pharyngitis
  3. Anterior Neck Pain in Thyroid region (unilateral or bilateral)
    1. Hallmark symptom and often presenting complaint
    2. Tender, swollen Thyroid Gland and adjacent neck with radiation into jaw in some cases
    3. Thyroid may swell to 3-4 times normal
  4. Associated symptoms
    1. Local compressive symptoms (e.g. Dysphagia)
    2. Hyperthyroidism symptoms (e.g. sweating, Tremor, weight loss)

VI. Signs

  1. Diffusely enlarged Thyroid
  2. No Proptosis (contrast with Grave's Disease)
  3. No pretibial Myxedema (contrast with Grave's Disease)

VII. Stages: Triphasic

  1. Phase 1: Hyperthyroidism (initial 4 to 8 weeks)
    1. Half of patients present in this phase
  2. Phase 2: Hypothyroidism (weeks to months)
    1. Develops in 30% of cases, and lasts up to 6 months
    2. May persist indefinately (in up to 15% of cases)
      1. May require longterm Thyroid Replacement
  3. Phase 3: Euthyroid
    1. Thyroid function normalizes by 6-12 months (up to 18 months) in 85% of cases

VIII. Differential Diagnosis

  1. See Painful Thyroiditis
  2. Suppurative Thyroiditis or Infectious Thyroiditis (rare)
    1. Associated with high fever, Leukocytosis and signs of toxicity
    2. FNA for culture and Gram Stain if suspected
  3. Radiation-Induced Thyroiditis (1% of I131 patients)
  4. Traumatic Thyroiditis (rare)
  5. Thyroid Hemorrhage into a Thyroid cyst

IX. Labs

  1. Thyroid Function Tests (variable depending on phase)
    1. Thyroid Stimulating Hormone (TSH)
    2. Free T4
  2. Acute phase reactants
    1. Erythrocyte Sedimentation Rate (ESR) >50 mm/hour
    2. C-Reactive Protein (CRP)
    3. Complete Blood Count
      1. Mild Leukocytosis
      2. Mild Anemia
  3. Thyroid antibodies and other Thyroid studies
    1. Thyroid stimulating Antibody negative (contrast with Grave's Disease)
    2. Thyroid peroxidase Antibody or TPO Antibody positive (but at lower levels than with Hashimoto Thyroiditis)
    3. Thyroglobulin level increased

X. Imaging

  1. Radioiodine Uptake (RAIU)
    1. Decreased uptake diffusely to <1-2%
    2. Contrast with Grave's Disease in which the uptake is increased diffusely
  2. Thyroid Ultrasound
    1. Nonuniform echotexture throughout the Thyroid Gland
    2. Contrast with cystic or solid mass in Hemorrhage or Infectious Thyroiditis

XI. Management

  1. Thyroid pain (may persist for 5 weeks from onset)
    1. NSAIDs (inital medication)
      1. Ibuprofen 600 mg every 6 hours as needed
    2. Prednisone 40-60 mg orally daily for 5-7 days, then taper over 4 weeks
      1. Indicated if pain refractory to NSAIDs after 4-7 days on NSAIDs
      2. Pain relieved in most cases by 48 hours
      3. Not preventive of Thyroid dysfunction or longterm Hypothyroidism
  2. Hyperthyroidism symptoms
    1. See Hyperthyroidism for symptomatic treatment
    2. Beta Blocker (e.g. Propranolol) may be used for symptomatic management
  3. Hypothyroidism management
    1. Levothyroxine indicated in symptomatic Hypothyroidism and chronic Hypothyroidism

XII. Course

  1. Spontaneous resolution in most cases by 12-18 months after onset
  2. Persistent Hypothyroidism occurs in up to 15% of cases
    1. Requires longterm Thyroid replacment
  3. Recurrence in 1 to 4% of cases

XIII. References

  1. Bindra (2006) Am Fam Physician 73(10):1769-76 [PubMed]
  2. Quintero (2021) Am Fam Physician 104(6): 609-17 [PubMed]
  3. Sweeney (2014) Am Fam Physician 90(6): 389-96 [PubMed]

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