1. W HAT IS H ASHIMOTO ’ S T HYROIDITIS ?

2. D EFINITION Hashimoto thyroiditis is part of the spectrum of autoimmune thyroid diseases (AITDs) and is characterized by the destruction of thyroid cells by various cell- and antibody-mediated immune processes. The most common cause of hypothyroidism in the United States in individuals older than 6 years. It was first described by the Japanese specialist Hakaru Hashimoto in Germany in 1912.

3. S TATISTICS United States It is the most common cause of hypothyroidism in the United States after age 6 years, with the incidence estimated to be 1.3% in a series of 5000 children aged 11-18 years International occurrence The annual incidence of Hashimoto thyroiditis worldwide is estimated to be 0.3-1.5 cases per 1000 persons.

4. P HYSICAL FINDINGS : Fatigue Constipation Dry skin Weight gain Puffy face and periorbital edema Cold, dry skin, which may be rough and scaly Peripheral edema of hands and feet, typically nonpitting Thickened and brittle nails (may appear ridged) Bradycardia Elevated blood pressure (typically diastolic hypertension) Diminished deep tendon reflexes and the classic prolonged relaxation phase Macroglossia Slow speech Ataxia Common S/S: Diagnosis:

6. PATHOPHYSIOLOGY Click here to see video.

7. MANAGEMENT Thyroid hormone replacement The drug of choice is individually tailored and titrated levothyroxine sodium administered orally, usually for life. A large goiter with obstructive symptoms, such as dysphagia, voice hoarseness, and stridor, caused by extrinsic obstruction of airflow Presence of a malignant nodule, as demonstrated by cytologic examination Presence of a lymphoma diagnosed on fine-needle aspiration Cosmetic reasons (eg, large, unsightly goiters) PharmacotherapySurgery

8. P ATIENT EDUCATION Patients should know that thyroid replacement therapy in Hashimoto thyroiditis is, except in very rare cases, lifelong. Patients must be informed about the importance of compliance with their replacement therapy and must be instructed to report any symptoms suggestive of hyperthyroidism caused by overreplacement. Patients must be instructed to separate—by at least 4 hours—ingestion of levothyroxine from ingestion of cholestyramine, ferrous sulfate, sucralfate, calcium carbonate, aluminum hydroxide (and other antacids), and iron-containing multivitamins, all of which impair the absorption of levothyroxine.