De Quervain thyroiditis

A 12 year old female presents to the endocrinology clinic with complaints of painful anterior neck swelling for 15 days. She also reports palpitations, sweating, and insomnia. There is a history of a recent upper respiratory infection 2 to 8 weeks prior to the onset of neck pain. On examination, blood pressure is 110/80 mm Hg, pulse rate is 102 beats per minute, respiratory rate is 18 breaths per minute, and temperature is 99.9 F. The thyroid gland is diffusely enlarged and tender on palpation. Thyroid function tests show low TSH with elevated T3 and T4 levels. Radioactive iodine uptake is decreased. Diagnosis?

Diagnosis is De Quervain thyroiditis (subacute granulomatous thyroiditis).

1. Definition

De Quervain thyroiditis is a self-limiting inflammatory disorder of the thyroid, most commonly triggered by a viral infection. It is associated with HLA B35 and is the most common cause of painful thyroiditis.

2. Etiology

2.1 Viral Trigger

1. Usually follows a viral upper respiratory infection
2. Occurs 2 to 8 weeks after infection
3. Often shows seasonal variation

3. Pathophysiology

3.1 Core Mechanism

1. Inflammatory destruction of thyroid follicular cells
2. Release of preformed T3 and T4
3. No new hormone synthesis

3.2 Disease Phases

1. Transient thyrotoxic phase
2. Euthyroid phase
3. Hypothyroid phase
4. Return to euthyroid state

4. Clinical Features

4.1 Core Features

1. Painful, tender thyroid
2. Neck pain radiating to jaw or ear
3. Low grade fever
4. History of recent viral illness

4.2 Thyrotoxic Symptoms

1. Palpitations
2. Sweating
3. Insomnia

4.3 Examination Findings

1. Diffuse thyroid tenderness

5. Diagnostic Evaluation

5.1 Thyroid Function Tests

1. Low TSH
2. Elevated T3 and T4

5.2 Inflammatory Markers

1. Elevated ESR
2. Elevated CRP

5.3 Radioactive Iodine Uptake

1. Low uptake

5.4 Ultrasound

1. Hypoechoic areas with reduced vascularity

5.5 Histopathology

1. Granulomatous inflammation with multinucleated giant cells

6. Key Diagnostic Insight

Painful thyroid + low RAIU + recent viral infection = De Quervain thyroiditis

7. Differential Diagnosis

1. Graves disease with increased RAIU
2. Hashimoto thyroiditis which is painless
3. Acute suppurative thyroiditis with systemic toxicity
4. Painless or postpartum thyroiditis

8. Management

8.1 General Course

1. Self-limiting condition, usually resolving within 3 to 4 months

8.2 Pain Control

1. NSAIDs or aspirin
2. Glucocorticoids for severe pain

8.3 Thyrotoxic Symptoms

1. Beta blockers such as propranolol
2. Antithyroid drugs are not indicated

8.4 Hypothyroid Phase

1. Levothyroxine only if symptomatic or TSH > 10

8.5 Monitoring

1. Thyroid function tests every 2 to 8 weeks

9. Complications

1. Transient hypothyroidism
2. Permanent hypothyroidism in a small percentage
3. Rare thyroid storm or arrhythmias

10. Key Clinical Insight

Hyperthyroidism due to hormone leakage, not increased synthesis, explains low RAIU

11. Exam Level Pearls

1. Painful thyroid is the key differentiator
2. Low RAIU distinguishes it from Graves disease
3. Triphasic course is classic
4. Post viral history is common
5. Antithyroid drugs should not be used