admittomedicine

thyroiditis

2 min read

clinical identity

Inflammation of the thyroid gland resulting in the release of pre-formed hormone (“Leak”). Characterized by Thyrotoxicosis Hypothyroidism Recovery and Low RAI Uptake.

pathophysiology & phases

  1. Thyrotoxic Phase (2–6 weeks): Follicular destruction releases stored T4/T3.
    • Labs: TSH, fT4/fT3. Low RAIU (<5%).
  2. Hypothyroid Phase (weeks to months): Stored hormone depleted; gland repairing.
    • Labs: TSH, fT4.
  3. Recovery: Euthyroidism (usually within 12 months).

classification by pain

The most clinically useful distinction for the exam is Painful vs Painless.

1. painful thyroiditis

  • Subacute Granulomatous (De Quervain’s):
    • Aetiology: Post-viral.
    • Presentation: Exquisite neck pain (radiates to jaw/ear), fever, malaise, symptoms of hyperthyroidism.
    • Labs: Markedly ESR/CRP. Negative/low antibodies.
    • Treatment: NSAIDs (first line). Prednisone 40mg taper if severe/refractory. Beta-blockers for symptoms.
  • Suppurative (Acute):
    • Aetiology: Bacterial infection (Staph/Strep), often via pyriform sinus fistula (children/young adults).
    • Presentation: Abscess formation, fever, fluctuant mass.
    • Tx: Antibiotics + Drainage.

2. painless thyroiditis

  • Silent (Lymphocytic) Thyroiditis:
    • Aetiology: Autoimmune (variant of Hashimoto’s).
    • Presentation: Mild thyrotoxicosis, nontender goitre.
    • Labs: Positive Anti-TPO. Normal ESR.
    • Tx: Beta-blockers only.
  • Postpartum Thyroiditis:
    • Definition: Occurs within 12 months of delivery.
    • Course: Classic Triphasic (Toxic Hypo Eu).
    • Recurrence: High risk in future pregnancies.
  • Drug-Induced:

management principles

Antithyroid Drugs (Methimazole/PTU) are not useful for thyroiditis.

mechanism of thyroiditis is release of pre-formed hormone, not new synthesis. ATDs target synthesis (TPO) and will be ineffective.

  • Thyrotoxic Phase: Symptomatic control with Beta-Blockers (Propranolol/Atenolol).
  • Hypothyroid Phase: Transient Levothyroxine if symptomatic.
    • Monitoring: Check TSH every 6–8 weeks. Attempt to wean T4 after 6–12 months to assess for permanent hypothyroidism (occurs in ~20% of Silent/Postpartum cases).