Thyroiditis, inflammation of the thyroid gland, has multiple etiologies.

Epidemiology

• Prevalence - 15% of population is affected
• Peak age - 20-50 years
• Sex - F>M

Classification

• Acute - bacterial, tuberculosis, fungal, radiation-induced
• Subacute - Viral, transient hyperthyroidism
• Silent -  includes postpartum
• Focal thyroiditis
• Autoimmune thyroiditis - Graves, Hashimoto

Clinical Presentation

• Hashimoto thyroiditis
  • Firm goiter
  • Disease is slowly progressive
  • May cause hypothyroidism related to glandular destruction
  • Usual symptoms are related to hypothyroidism due to gland destruction
• Graves disease
  • 60-80% of thyrotoxicosis cases are caused by Graves
  • Constitutional
    • Weight loss, heat and cold intolerance, fatigue
  • Cardiovascular
    • Tachycardia, high output heart failure
  • Ophthalmologic
    • Ophthalmopathy
    • Proptosis, usually bilateral

Prognosis

• TSHR - presence after treatment for Graves is indicative of possible relapse

Diagnosis

• Indications for testing - signs of hypo- or hyperthyroidism and family history of thyroid disease
• Laboratory testing
  • Establish if hypo- or hyperthyroidism is present
  • If patient is hypothyroid and TSH is elevated and T4 is low - most likely Hashimoto
  • If patient is hypo- or hyperthyroid and TSH and T4 are elevated - most likely Graves  
• Antibody screening - if thyroid disease identified
  • Thyroid Peroxidase Antibody (TPO)
    • Also known as thyroid microsomal antibody
    • Presence of antibody denotes autoimmune thyroid disease
    • Generally found in Hashimoto and in Graves, postpartum thyroiditis and subacute thyroiditis
    • If found in euthyroid patients, may indicate a risk for autoimmune thyroid disease
    • Presence of TPO antibodies may be associated with
      • Vitiligo
      • Pernicious anemia
      • Diabetes mellitus type 1
      • Hypoparathyroidism
      • Celiac disease
      • Hypophysitis
      • Addison disease
  • Thyroglobulin Antibody (Tg)
    • Less useful antibody compared to TPO in diagnosing autoimmune thyroid disease, but is diagnostic of Hashimoto if present
    • Presence may predict postpartum thyroiditis
    • Presence of Tg antibodies may be associated with
      • Vitiligo
      • Pernicious anemia
      • Diabetes mellitus type 1
      • Hypoparathyroidism
      • Celiac disease
      • Hypophysitis
      • Addison disease
  • Thyroid Stimulating Hormone Receptor Antibody (TSHR)
    • Presence is diagnostic for Graves with hyperthyroidism
  • Thyroid Stimulating Immunoglobulin (TSI)
    • Presence is indicative of Graves

Disease Monitoring

• TSH followed by T4 to assess thyroid status
• Change medication dosing

Differential Diagnosis

• Toxic nodular goiter
• Thyroid cancer
• Thyrotoxicosis factitia
• Viral, subacute thyroiditis
• Pituitary tumor