Description

Autoimmune disease in which thyroid-stimulating hormone (TSH) receptor activation by thyrotropin receptor antibodies (TRAb) cause increased thyroid hormone secretion; most common cause of hyperthyroidism; classic findings are thyrotoxicosis, diffuse goiter, ophthalmopathy (orbitopathy), and occasionally localized dermopathy (pretibial myxedema).

Epidemiology

Incidence

• Annual incidence of 20 to 50 cases per 100,000 persons
• Peaks between 30 and 50 years of age
• Occurs in 0.2% of pregnancies, of which 95% is due to Graves disease
• Graves disease accounts for 60–80% of all cases of hyperthyroidism.

Prevalence
Has been reported to affect 1–1.5% of the world population

Etiology and Pathophysiology

• Excessive production of TSH receptor antibodies from B cells primarily within the thyroid, likely due to genetic clonal lack of suppressor T cells
• Binding of these antibodies to TSH receptors in the thyroid activates the receptor, stimulating thyroid hormone synthesis and secretion as well as thyroid growth (leading to goiter).
• Binding to similar antigen in retro-orbital connective tissue causes ocular symptoms.

Genetics

• Higher risk with personal or family history of any autoimmune disease, especially Hashimoto thyroiditis
• Twin studies show concordance rate as high as 20%.

Risk Factors

• Female gender (5 to 10 times more than men)
• Postpartum period
• Family history (15% of patients with Graves disease have an affected relative.)
• Medications: iodine, selenium, amiodarone, lithium, highly active antiretroviral therapy (HAART); rarely, immune-modulating medications (e.g., interferon therapy)
• Smoking (higher risk of developing ophthalmopathy)
• Low vitamin D levels
• Bacterial/viral infections

General Prevention

Screening TSH in asymptomatic patients is not recommended.

Commonly Associated Conditions

• Mitral valve prolapse
• Type 1 diabetes mellitus
• Addison disease, hypokalemic periodic paralysis
• Vitiligo, alopecia areata
• Other autoimmune disorders