Endocrinology · Thyroid Disorders
The facts most likely to be tested
Subacute thyroiditis typically presents as a painful, tender thyroid gland following a recent viral upper respiratory infection.
The clinical course follows a triphasic pattern starting with transient hyperthyroidism due to follicular rupture and hormone release.
Laboratory findings demonstrate a suppressed TSH, elevated T4/T3, and a significantly elevated erythrocyte sedimentation rate (ESR).
Radioactive iodine uptake (RAIU) scan will show diffusely decreased uptake because the gland is damaged and unable to synthesize new hormone.
Histopathology of the thyroid gland reveals granulomatous inflammation with multinucleated giant cells.
First-line treatment for pain and inflammation is nonsteroidal anti-inflammatory drugs (NSAIDs).
Beta-blockers are indicated for symptomatic management of thyrotoxicosis during the initial hyperthyroid phase.
Vignette unlocked
A 34-year-old woman presents with a 1-week history of severe anterior neck pain that radiates to her jaw. She reports a recent episode of fever and rhinorrhea two weeks ago. On physical exam, the patient is tachycardic and the thyroid gland is exquisitely tender to palpation. Laboratory studies reveal a suppressed TSH, elevated free T4, and an ESR of 85 mm/hr. A radioactive iodine uptake scan shows near-absent uptake throughout the gland.
What is the most appropriate initial treatment for this patient's condition?
NSAIDs
The patient presents with the classic triad of post-viral neck pain, thyrotoxicosis, and elevated ESR, diagnostic of subacute thyroiditis; NSAIDs are the first-line treatment for pain and inflammation.
Full handout
High yield triage
Etiology / Epidemiology
Post-viral inflammatory process, most common in women 30-50 years old.
Clinical Manifestations
Classic painful thyroid following a viral URI with transient hyperthyroidism.
Diagnosis
Diagnosis is clinical; elevated ESR and low radioactive iodine uptake (RAIU) are diagnostic.
Treatment
NSAIDs are first-line for pain; avoid antithyroid drugs as the process is self-limiting.
Prognosis
Most patients achieve euthyroid status within 12 months; rare progression to permanent hypothyroidism.
Full handout
Epidemiology & Etiology
Typically follows a viral upper respiratory infection (e.g., coxsackievirus, mumps, or influenza). It is the most common cause of a painful thyroid gland. Incidence peaks in middle-aged women.
Pertinent Anatomy
The thyroid gland becomes enlarged and firm due to granulomatous inflammation. The tenderness is often localized to one lobe but frequently migrates to the contralateral side.
Pathophysiology
Viral infection triggers a granulomatous inflammatory response, causing follicular cell destruction. This leads to the release of preformed T4 and T3 into the circulation, resulting in a transient thyrotoxic phase. As stores deplete, the patient may transition to a transient hypothyroid phase before recovery.
Clinical Manifestations
Patients present with a painful, tender thyroid and systemic symptoms like fever and malaise. The physical exam reveals a firm, tender goiter. Red flags include severe dysphagia or airway compromise due to rapid gland enlargement.
Diagnosis
The erythrocyte sedimentation rate (ESR) is characteristically markedly elevated (often >50-100 mm/hr). The radioactive iodine uptake (RAIU) scan is the gold standard to differentiate from Graves disease, showing near-absent uptake due to suppressed TSH. TSH is low and T4/T3 are high during the initial phase.
Treatment
NSAIDs (e.g., ibuprofen or naproxen) are the first-line treatment for pain and inflammation. Do not use antithyroid medications (e.g., methimazole) because the thyrotoxicosis is due to leakage, not overproduction. Use beta-blockers (e.g., propranolol) for symptomatic relief of palpitations or tremors.
Prognosis
The condition is self-limiting, with most patients returning to a euthyroid state within weeks to months. Approximately 5-10% of patients may develop permanent hypothyroidism requiring lifelong levothyroxine.
Differential Diagnosis
Graves disease: diffuse goiter with high RAIU
Suppurative thyroiditis: acute bacterial infection with abscess formation
Silent thyroiditis: painless thyroid gland
Hashimoto thyroiditis: painless, firm, rubbery goiter
Amiodarone-induced thyroiditis: history of medication use