Hypothyroidism is a condition in which the thyroid gland does not produce adequate amounts of thyroid hormone, resulting in an abnormal slowing of the body's chemical and cellular functions.
The thyroid gland is a small bow-tie shaped endocrine gland located in the lower neck. It produces thyroid hormone under regulation by the brain and the pituitary gland.
Thyroid hormone, which is released into the body, regulates multiple body functions. It is important in maintaining normal metabolism. Thyroid hormone also helps maintain normal cholesterol balance, heart function, and brain function. Almost every system of the body is affected by hypothyroidism.
Early in the course of hypothyroidism, symptoms may be quite subtle. These may include: fatiguedecreased concentrationintolerance to cold environmentsconstipationloss of appetitemuscle cramping and stiffnessweight gainsome individuals may notice hair loss, dry skin, or nail changes
If left untreated, the symptoms of hypothyroidism will progress. This can lead to fluid retention around the eyes or legs. Untreated hypothyroidism can also cause congestive heart failure, a condition in which a weakened heart is unable to pump enough blood to body organs.
In extreme cases, the brain itself is affected. The person can lose mental function and even go into a coma.
Hypothyroidism is most commonly caused by an autoimmune disorder, a condition in which the body produces antibodies that attack its own cells for no known reason.
Hashimoto's thyroiditis is an example of an autoimmune disorder that attacks the thyroid gland. Over time, this makes the thyroid gland unable to produce normal amounts of thyroid hormone.
Some individuals have an overactive thyroid, a condition known as hyperthyroidism. Medications can be given to destroy a portion of an overactive thyroid. If too much medication is given, the person can develop low thyroid function, or hypothyroidism.
Surgery to remove the thyroid gland in someone with a condition such as thyroid cancer can also cause hypothyroidism.
There is no known way to prevent autoimmune disorders that cause hypothyroidism, such as Hashimoto's thyroiditis. Careful monitoring of medications used to treat an overactive thyroid can help prevent hypothyroidism caused by destruction of too much of the gland tissue.
Diagnosis of hypothyroidism begins with a complete history and physical examination. Thyroid function tests and other related blood chemistry tests are needed. An antibody titer blood test may be done to see if the hypothyroidism is caused by an autoimmune disorder.
The long-term effects of untreated hypothyroidism can be profound. Severe, prolonged hypothyroidism can lead to multiple abnormalities within any system of the body including heart, brain, and skin. Untreated hypothyroidism can cause heart disease, osteoporosis or thinning of the bones, and infertility in women.
If left untreated for many years, severe hypothyroidism can eventually lead to death. The findings of a recent study have shown that pregnant women with hypothyroidism have 4 times the risk of miscarriage in the second trimester compared to other women. If hypothyroidism in pregnancy is not treated appropriately, it can lead to mental retardation in the child.
Hypothyroidism is not contagious and poses no risk to others.
Generally, there is no way to reverse the damage done to the thyroid gland. The healthcare professional will prescribe thyroid hormone, such as levothyroxine (i.e., Levothroid, Levoxyl, Synthroid, Unithroid) or liothyronine (i.e., Cytomel, Triostat), to be taken on a daily basis. The right dose of medication should resolve the signs and symptoms of hypothyroidism.
If a person has had hypothyroidism for many years, the replacement of thyroid hormone may be started slowly and eventually increased to normal levels. Because the thyroid hormone medication is chemically identical to the body's thyroid hormone, side effects or allergic reactions to the medications are quite rare.
If too much thyroid hormone is given, the person may develop arrhythmias, or irregular heartbeats, and osteoporosis, or thinning of the bones.
Treatment of hypothyroidism is lifelong.
The healthcare professional will use periodic thyroid function tests to monitor the level of medication needed. These blood tests may initially be done every 6 to 8 weeks, until a normal level of thyroid is restored.
After the right dose of medication is established, thyroid function tests may then be done every 6 to 12 months. Any new or worsening symptoms should be reported to the healthcare professional.