infectious thyroiditis; suppurative thyroiditis; acute thyroiditis

Introduction

Infectious thyroiditis, suppurative thyroiditis or acute thyroiditis is an uncommon form of thyroiditis caused by bacterial seeding of the thyroid, almost invariably from a blood-borne primary infection originating elsewhere.

Etiology

• bacterial (68%)
  • Staphylococcus
  • Streptococcus
  • Salmonella
  • Enterobacter
  • Mycobacterium tuberculosis
• fungi (15%)
  • Candida
  • Aspergillus
  • Mucor
• parasitic (<1%)

(Viral thyroiditis causes subacute granulomatous thyroiditis)

Epidemiology

• most common in women 20-40 years of age
• 50-60% of patients have pre-existing thyroid disease
• 70% have concurrent upper respiratory tract infection

Clinical manifestations

• abrupt onset of illness, may be preceded by upper respiratory tract infection (URI)
  • anterior neck pain (100%)
  • fever (92%)
  • dysphagia (91%)
• 4 phases of disease occurring over 4-6 months
  • initial acute hyperthyroid phase (2-3 weeks)
  • euthyroid phase
  • hypothyroid phase (weeks to months)
  • asymptomatic recovery phase

Laboratory

• complete blood count (CBC) - increased WBC (70%)
• fine-needle aspiration (FNA), Gram stain & culture
• T4 generally normal
• radioactive iodine uptake (RAIU) generally normal
• thyroid auto-antibodies generally negative

Radiology

ultrasound to exclude cervical abscess

Differential diagnosis

• hemorrhage into adenoma or carcinoma
• malignant neoplasm of thyroid
  • fast growth with focal necrosis may mimic pyogenic infection
  • hyperthyroidism may result from neoplasm by release of colloid-stored thyroxine
• subacute granulomatous thyroiditis

Management

• parenteral antibiotics
• non-steroidal anti-inflammatory drugs (NSAIDs)
• surgical drainage of abscess
• rest & local heat
• follow-up
  • permanent sequelae rare
  • hypothyroidism may occur if gland destruction is extensive
  • recurrences suggest anatomic anomaly
    • persistent thyroglossal duct
    • fistula

More general terms

• thyroiditis

Additional terms

• radioactive iodine uptake (RAIU) test