Thyroid, Autoimmune

Thyroid, Autoimmune

 

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

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  
  • Order antibody screening
    • 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

Differential Diagnosis

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

Disease Monitoring

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

Prognosis

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

See Also