Hypothyroidism is a common and potentially serious endocrine disorder in the general population. It is more common in women, the elderly, and whites. In the United States, the incidence in women over the age of 60 years is up to 20%, and in men over the age of 74 years it is up to 15%.
Common causes of hypothyroidism include inadequate levels of dietary iodine intake, pregnancy, radiotherapy to the thyroid gland, viral infections, surgery, infiltrative disorders including lymphoma, carcinoma and iron overload, autoimmune diseases, type I diabetes, administration of amiodarone or lithium, and rare congenital factors.
The physiological effects of hypothyroidism are widespread and include cardiovascular, renal, gastrointestinal, neurological, and endocrine abnormalities. The clinical manifestations range from asymptomatic individuals to severe symptoms including congestive heart failure, adrenal insufficiency, psychosis, and coma (Table 1).
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