subacute lymphocytic thyroiditis

Introduction

A poorly understood & uncommon cause of goitrous hyperthyroidism.

Etiology

• viral etiology suggested for sporadic form
• autoimmune etiology suggested for postpartum form

Pathology

• foci of lymphocytic infiltration
• increased interstitial fibrous tissue (occasional)

Clinical manifestations

• abrupt onset of hyperthyroidism
• mild, goitrous enlargement of gland
• painless thyroiditis
• may progress to hypothyroidism
• usually self-limited without sequelae

Laboratory

• increased T3 & T4
• antithyroid microsomal Ab may be seen in low titers
• erythrocyte sedimentation rate (ESR) normal or mildly elevated
• antimicrosomal (thyroid peroxidase) antibody may be positive in postpartum form

Radiology

• radioactive iodide uptake is low

Differential diagnosis

• Graves disease
• subacute granulomatous thyroiditis
• multinodular goiter
  • thyrotoxicosis after exposure to iodine containing contrast media
  • thyroid nodules

Management

• reassurance & observation
• pharmacologic agents
  • propranolol 20-40 mg PO QID for hyperthyroidism
  • Synthroid 0.05 to 0.15 mg QD for hypothyroidism
  • prednisone 20-40 mg QD
    • severe cases not responding to other therapy
    • taper after 1 week with discontinuation in 2-4 weeks
    • restart if pain recurs
• thyroidectomy for recurrent, disabling episodes
• follow-up
  • 54% with persistent thyroid abnormality
  • anti-microsomal Ab positive postpartum thyroiditis generally resolves in 2-4 months
  • patients with postpartum thyroiditis should be monitored for development of hypothyroidism
  • anti microsomal antibody screening
    • prior history of postpartum thyroiditis
    • prior history of thyroid disease

More general terms

• thyroiditis
• hyperthyroidism

More specific terms

• postpartum thyroiditis