A 48-year-old woman with a history of autoimmune thyroid disease presents with acute onset of severe thyroid pain, fever, and elevated inflammatory markers (ESR 95 mm/h, CRP 12 mg/dL). Thyroid ultrasound shows heterogeneous echotexture with preserved vascularity on Doppler. TSH is suppressed and free T4 is elevated. Fine-needle aspiration shows lymphocytic infiltration without suppuration. What is the drug of choice for acute phase management of subacute (de Quervain) thyroiditis?

Explanation

## Subacute (de Quervain) Thyroiditis: Viral-Mediated Autoimmune Inflammation ### Pathophysiology Subacute de Quervain thyroiditis is a self-limited, viral-triggered autoimmune inflammation of the thyroid characterized by lymphocytic infiltration, granuloma formation, and destruction of thyroid follicles. It typically follows an upper respiratory viral infection and progresses through three phases: thyrotoxic, euthyroid, and hypothyroid. ### Drug of Choice for Acute Phase **Key Point:** NSAIDs (e.g., ibuprofen, indomethacin) or prednisolone are first-line agents for acute subacute thyroiditis. NSAIDs are preferred for mild-to-moderate disease; prednisolone is reserved for severe symptoms or NSAID failure. ### Treatment Algorithm by Severity ```mermaid flowchart TD A[Subacute de Quervain Thyroiditis]:::outcome --> B{Symptom Severity?}:::decision B -->|Mild-Moderate| C[NSAIDs: Ibuprofen or Indomethacin]:::action B -->|Severe/Refractory| D[Prednisolone 20-40 mg daily, taper over 4-6 weeks]:::action C --> E{Response in 1-2 weeks?}:::decision E -->|Yes| F[Continue NSAID, monitor TSH]:::action E -->|No| G[Switch to prednisolone]:::action D --> H[Gradual taper as symptoms resolve]:::action H --> I[Monitor for hypothyroid phase]:::outcome ``` ### Phase-Specific Management | Phase | Duration | Pathophysiology | Management | |---|---|---|---| | **Thyrotoxic** | 2–6 weeks | Follicular destruction, hormone release | NSAIDs or prednisolone for pain/inflammation | | **Euthyroid** | 1–3 weeks | Hormone depletion, recovery begins | Supportive care only | | **Hypothyroid** | Variable | Persistent thyroid damage, TSH rise | Levothyroxine if TSH elevated and symptomatic | ### NSAID vs. Prednisolone Selection **High-Yield:** NSAIDs (ibuprofen 400–600 mg TID, indomethacin 50–100 mg daily) are first-line for mild-to-moderate disease. Prednisolone (20–40 mg daily, tapered over 4–6 weeks) is reserved for: - Severe, disabling pain unresponsive to NSAIDs - Recurrent episodes - Immunocompromised patients - Intolerance to NSAIDs **Clinical Pearl:** Prednisolone provides faster symptom relief than NSAIDs and reduces recurrence risk, but prolonged use carries metabolic and immunosuppressive risks. NSAIDs are preferred as first-line to minimize steroid exposure. ### Why Other Options Are Incorrect **Amoxicillin-clavulanate:** Subacute thyroiditis is viral-triggered, not bacterial. Antibiotics have no role unless secondary bacterial infection occurs (rare). **Levothyroxine monotherapy:** Levothyroxine is indicated only in the hypothyroid phase if TSH is elevated and symptoms persist. It is not used in the acute thyrotoxic phase and does not treat inflammation. **Propylthiouracil (PTU):** PTU blocks thyroid hormone synthesis and is used in Graves' disease (autoimmune thyroid stimulation). In subacute thyroiditis, thyroid hormone is released from destroyed follicles, not newly synthesized—PTU is ineffective and unnecessary. **Mnemonic:** **NSAID-First for de Quervain** — NSAIDs are the first-line anti-inflammatory; prednisolone is the second-line for severe disease. Avoid antibiotics (not bacterial), levothyroxine (not acute phase), and PTU (hormone release, not synthesis). [cite:Harrison 21e Ch 405; Robbins 10e Ch 24]