The purpose of treatment is to replace the thyroid hormone that is lacking. Levothyroxine is the most commonly used medication. Doctors will prescribe the lowest dose that effectively relieves symptoms and brings the TSH level to a normal range. If you have heart disease or you are older, your doctor may start with a very small dose.

Lifelong therapy is required unless you have a condition called transient viral thyroiditis.

You must continue taking your medication even when your symptoms go away. When starting your medication, your doctor may check your hormone levels every 2 - 3 months. After that, your thyroid hormone levels should be monitored at least every year.

Important things to remember when you are taking thyroid hormone are:

• Do NOT stop taking the medication when you feel better. Continue taking the medication exactly as directed by your doctor.
• If you change brands of thyroid medicine, let your doctor know. Your levels may need to be checked.
• Some dietary changes can change the way your body absorbs the thyroid medicine. Talk with your doctor if you are eating a lot of soy products or a high-fiber diet.
• Thyroid medicine works best on an empty stomach and when taken 1 hour before any other medications. Do NOT take thyroid hormone with calcium, iron, multivitamins, aluminum hydroxide antacids, colestipol, or other medicines that bind bile acids, or fiber supplements.

After you start taking replacement therapy, tell your doctor if you have any symptoms of increased thyroid activity (hyperthyroidism) such as:

• Rapid weight loss
• Restlessness or shakiness
• Sweating

Myxedema coma is a medical emergency that occurs when the body's level of thyroid hormones becomes extremely low. It is treated with intravenous thyroid hormone replacement and steroid medications. Some patients may need supportive therapy (oxygen, breathing assistance, fluid replacement) and intensive-care nursing.

In most cases, thyroid levels return to with proper treatment. However, thyroid hormone replacement must be taken for the rest of your life.

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 people with untreated hypothyroidism.

Symptoms and signs of myxedema coma include:

• Below normal temperature
• Decreased breathing
• Low blood pressure
• Low blood sugar
• Unresponsiveness

Other complications are:

• Heart disease
• Increased risk of infection
• Infertility
• Miscarriage

People with untreated hypothyroidism are at increased risk for:

• Giving birth to a baby with birth defects
• Heart disease because of higher levels of LDL ("bad") cholesterol
• Heart failure

People treated with too much thyroid hormone are at risk for angina or heart attack, as well as osteoporosis (thinning of the bones).

Call your health care provider if you have symptoms of hypothyroidism (or myxedema).

If you are being treated for hypothyroidism, call your doctor if:

• You develop chest pain or rapid heartbeat
• You have an infection
• Your symptoms get worse or do not improve with treatment
• You develop new symptoms