Thyroiditis

Key Features

Essentials of Diagnosis

• Autoimmune thyroiditis (Hashimoto)

  • Most common thyroiditis

  • Antithyroperoxidase or antithyroglobulin antibodies usually high

  • Often progresses to hypothyroidism

• Painful subacute thyroiditis

  • Hallmark is tender thyroid gland with painful dysphagia

  • Elevated erythrocyte sedimentation rate (ESR)

  • Low antithyroid antibodies distinguish it from autoimmune thyroiditis

• Infectious thyroiditis

  • Severe, painful thyroid gland

  • Febrile with leukocytosis and elevated ESR

• Riedel thyroiditis

  • Most often in middle age or older women

  • Usually part of a systemic fibrosing syndrome

General Considerations

• Classification

  • Autoimmune (Hashimoto) thyroiditis (chronic lymphocytic thyroiditis)

    • Most common thyroid disorder in the United States

    • Due to autoimmunity

    • Frequency increased by dietary iodine supplementation

    • Certain drugs can trigger autoimmune thyroiditis: alemtuzumab, amiodarone, interferon-alpha, interleukin-2, ipilimumab, lenalidomide, lithium, thalidomide, tremelimumab, and tyrosine kinase inhibitors

    • Associated with other autoimmune diseases, eg, inflammatory bowel disease, pernicious anemia, Sjögren syndrome, vitiligo, and celiac disease (gluten enteropathy)

    • Rarely associated with other autoimmune conditions such as alopecia areata, hypophysitis, encephalitis, membranous nephropathy myocarditis, or primary pulmonary hypertension

  • Subacute thyroiditis (de Quervain thyroiditis, granulomatous thyroiditis, and giant cell thyroiditis)

    • Relatively common

    • Believed to be caused by viral infection

  • Infectious thyroiditis: rare, caused by pyogenic organisms, usually during systemic infection

  • Postpartum thyroiditis (autoimmune): causes transient hyperthyroidism followed by hypothyroidism

  • Riedel thyroiditis (also known as invasive fibrous thyroiditis, Riedel struma, woody thyroiditis, ligneous thyroiditis, and invasive thyroiditis)

    • Rarest form

    • Usually a manifestation of a multifocal systemic fibrosis syndrome

    • May occur a thyroid manifestation of IgG₄-related systemic disease

• Chronic hepatitis C is associated with an increased risk of autoimmune thyroiditis, with 21% of affected patients having antithyroid antibodies and 13% having hypothyroidism

Demographics

• Autoimmune (Hashimoto) thyroiditis

  • Often familial, varies by kindred and by race

  • Six times more common in women

• Antithyroid antibodies in US adolescents and adults found in

  • 3% of men and 13% of women

  • 25% of women over age 60 years

  • 14% of whites

  • 11% of Mexican Americans

  • 5% of blacks

• Subacute thyroiditis accounts for 5% of clinical thyroid disease

• Riedel thyroiditis usually affects middle-aged or elderly women

• 40% of women and 20% of men exhibit focal thyroiditis at autopsy

Clinical Findings

Symptoms and Signs

Autoimmune (Hashimoto) thyroiditis

• Thyroid gland usually diffusely enlarged, firm, and finely nodular

• One lobe may be asymmetrically enlarged, raising concern for neoplasm

• Neck tightness; pain and tenderness not usually present

• The thyroid is fibrotic and atrophic in about 10% of cases, particularly in older women

• Mild dry mouth (xerostomia) or dry eyes (keratoconjunctivitis sicca) related to Sjögren syndrome in ~33%

• Diplopia due to coexistent myasthenia gravis

• Manifestations of other autoimmune diseases listed above

Painful subacute thyroiditis

• Acute, usually painful, thyroid enlargement, with dysphagia

• Pain may radiate to ears

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