Subacute Thyroiditis (de Quervain Thyroiditis)

Presentation

• Often post-URTI onset.

• Presents as a tender, painful thyroid with diffuse goitre.

• Pain may radiate to the ear or jaw.

• Associated symptoms may include fever and malaise.

____________________________________

Disease Course

• Typically progresses through three phases:

  • Hyperthyroid phase lasting a few weeks.

  • Hypothyroid phase lasting up to 6 months.

  • Returns to normal in most cases; however, 1/3 may develop permanent hypothyroidism.

• High recurrence rate for those who revert to normal.

____________________________________

Differentials

• Infectious thyroiditis

• Hashimoto's thyroiditis

• Graves' disease

• Thyroid cancer

• Postpartum thyroiditis (resolve within 6–12 months; 1/3 may develop permanent hypothyroidism)

____________________________________

Diagnosis

• Radionuclide scan: shows no uptake (indicative of thyroiditis).

• ESR/CRP: typically elevated.

• Thyroid function tests (TFTs): should be monitored every 4–8 weeks.

• Thyroid peroxidase (TPO) antibodies: test if postpartum thyroiditis is suspected to confirm diagnosis.

____________________________________

Management

Anti-inflammatory Medications:

• Aspirin: 600 mg QID for mild cases.

• Ibuprofen: 400 mg TDS.

Beta-blocker (Propranolol):

• 10 mg BD for symptom management in hyperthyroid phase.

• No need for thionamides (antithyroid drugs) in hyperthyroid phase as it's not due to overproduction of thyroid hormones.

Thyroxine:

• If symptomatic for hypothyroidism or TSH >10 mIU/L.

• Start at 50-100 mcg daily for 4-8 weeks, adjust as needed based on follow-up.

Corticosteroids (for severe cases):

• Prednisolone: Start at 40 mg daily, downtitrating over 2-4 weeks if severe and if NSAIDs are ineffective.

____________________________________

Prognosis and Follow-up

• Subacute thyroiditis typically resolves within 6–12 months.

• Monitor TSH levels every 4-8 weeks initially, then every 6-12 months if stable.

• Long-term risk of hypothyroidism; hence, continue yearly TSH monitoring even if thyroid function returns to normal.

____________________________________

Notes:

• Etiology: Exact cause is unknown, but it is often triggered by viral infections, hence sometimes referred to as post-viral thyroiditis.

• Patient Education: Inform patients about the transient nature of the disease, typical course, and the importance of follow-up testing to prevent long-term complications.