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Alternative namesMyxedema; Adult hypothyroidism
Hypothyroidism is a condition in which the thyroid gland fails to produce enough thyroid hormone.
Causes, incidence, and risk factorsThe thyroid gland, located in the front of the neck just below the larynx, secretes hormones that control metabolism . These hormones are thyroxine ( T4 ) and triiodothyronine ( T3 ).
The secretion of T3 and T4 is controlled by the pituitary gland and the hypothalamus , which is part of the brain. Thyroid disorders may result not only from defects in the thyroid gland itself, but also from abnormalities of the pituitary or hypothalamus.
Hypothyroidism, or underactivity of the thyroid gland, may cause a variety of symptoms and may affect all body functions. The body's normal rate of functioning slows, causing mental and physical sluggishness. The symptoms may vary from mild to severe, with the most severe form called myxedema, which is a medical emergency.
Risk factors include age over 50 years, female gender, obesity , thyroid surgery, and exposure of the neck to x-ray or radiation treatments.
Additional symptoms that may be associated with this disease:
Signs and tests
A physical examination reveals delayed relaxation of muscles during tests of reflexes. Pale, yellow skin; loss of the outer edge of the eyebrows; thin and brittle hair; coarse facial features; brittle nails; firm swelling of the arms and legs; and mental slowing may be noted. Vital signs may reveal slow heart rate , low blood pressure , and low temperature.
Additional laboratory abnormalities may include:
The purpose of treatment is to replace the deficient thyroid hormone. Levothyroxine is the most commonly used medication. The lowest dose effective in relieving symptoms and normalizing the TSH is used. Life-long therapy is needed. Medication must be continued even when symptoms subside. Thyroid hormone levels should be monitored yearly after a stable dose of medication is determined.
With treatment, return to the normal state is usual. Life-long medication is needed. Myxedema coma can result in death.
Myxedema coma , the most severe form of hypothyroidism, is rare. It may be caused by an infection, illness, exposure to cold, or certain medications in an individual with untreated hypothyroidism. Symptoms and signs of myxedema coma include unresponsiveness, decreased breathing, low blood pressure , low blood sugar , and below normal temperature.
Calling your health care provider
Call your health care provider if signs of hypothyroidism (or myxedema) are present.
There is no prevention for hypothyroidism; however, screening tests in newborns can detect congenital hypothyroidism.
Update Date: 5/10/2002Stephanie Fish, M.D., Division of Endocrinology, University of Pennsylvania Medical Center, Philadelphia, PA. Review provided by VeriMed Healthcare Network.
Last updated: Tue, 06 Jan 2009 00:20:03 GMT