Thyroiditis

Key Features

Essentials of Diagnosis

Autoimmune thyroiditis

• Chronic lymphocytic (Hashimoto) thyroiditis is the most common thyroiditis and often progresses to hypothyroidism

• Postpartum thyroiditis and subacute lymphocytic thyroiditis (silent thyroiditis) can cause transient hyperthyroidism due to passive release of stored thyroid hormone

• Thyroid peroxidase antibodies (TPO Ab) or thyroglobulin antibodies (Tg Ab) are usually high

Painful subacute thyroiditis (de Quervain thyroiditis)

• Hallmark is tender thyroid gland with painful dysphagia

• Elevated erythrocyte sedimentation rate (ESR)

• Viral etiology. Antithyroid antibodies are absent or low, distinguishing it from autoimmune thyroiditis.

Infectious (suppurative) thyroiditis

• Severe, painful thyroid gland

• Febrile with leukocytosis and elevated ESR

IgG₄-related thyroiditis (Riedel thyroiditis)

• Most often in middle age or older women

• Usually part of a systemic fibrosing syndrome

General Considerations

Autoimmune thyroiditis

• Chronic lymphocytic thyroiditis, also known as "Hashimoto thyroiditis," is the most common thyroid disorder in the United States

• Often progresses to hypothyroidism

• Incidence of autoimmune thyroiditis varies by kindred, race, and sex; it is commonly familial

• In the United States, elevated levels of antithyroid antibodies are found in

  • 14.3% of Whites

  • 10.9% of Mexican Americans

  • 5.3% of Blacks

• Dietary iodine supplementation (especially when excessive) increases the risk of autoimmune thyroiditis

• Certain medications can trigger autoimmune thyroiditis, including

  • Tyrosine kinase inhibitors

  • Alemtuzumab

  • Interferon-alpha

  • Interleukin-2

  • Thalidomide, lenalidomide

  • Lithium

  • Amiodarone

  • Immune checkpoint inhibitors

• Thyroiditis is frequently associated with other autoimmune conditions

  • Pernicious anemia

  • Sjögren syndrome

  • Vitiligo

  • Inflammatory bowel disease, celiac disease, and gluten sensitivity

• Chronic hepatitis C

  • Associated with an increased risk of autoimmune thyroiditis

  • 21% of affected patients having antithyroid antibodies

  • 13% having hypothyroidism

• Postpartum thyroiditis

  • An acute autoimmune thyroiditis that occurs soon after delivery in about 7% of women

  • Most women recover normal thyroid function

  • Occurs commonly in women who have

    • High levels of TPO Ab in the first trimester of pregnancy or immediately after delivery

    • Preexistent type 1 diabetes mellitus

    • Other autoimmunity

    • Family history of autoimmune thyroiditis

• Painless (silent) sporadic subacute thyroiditis

  • A form of autoimmune thyroiditis that is similar to postpartum thyroiditis, except that it is not related to pregnancy

  • Causes include amiodarone and immunotherapy

  • Accounts for about 1% of cases of thyrotoxicosis and is followed by hypothyroidism that may resolve spontaneously

Painful subacute thyroiditis

• Also called de Quervain thyroiditis, granulomatous thyroiditis, and giant cell thyroiditis

• Relatively common

• Most affected patients have transient hyperthyroidism, followed by hypothyroidism

• Typically associated with a viral infection (including COVID-19) and often follows an upper respiratory tract infection

• Incidence peaks in the summer to early autumn

• Affects both sexes; young and middle-aged women are most commonly affected

Infectious (suppurative) thyroiditis