Symptoms and Treatment for Underactive Thyroid
Thyroid symptoms can be hard to recognize. Learn what to look for and what to expect at the doctor visit for an underactive thyroid.

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image of woman with thyroid ailment Symptoms and Treatment for Underactive Thyroid

You're tired. Your whole body seems to have slowed down. Maybe your skin is dry and you always feel cold. The problem could be your thyroid gland. This is a flat, butterfly shaped organ in the front of the neck. It makes thyroid hormone. Nearly every tissue uses thyroid hormone. It affects body temperature, use of energy, muscle strength and many other functions. If your thyroid doesn't make enough hormone, you could have hypothyroidism, or an underactive thyroid.

About one out of 10 Americans suffer from thyroid disease. Many go undiagnosed, in part because the symptoms are so vague. Although the disease is more common in women, it also strikes men, especially elderly men.

What is hypothyroidism?
In hypothyroidism the thyroid does not produce enough thyroid hormone. This slows down body function. You may:

  • Feel cold, even though it's warm
  • Tire more easily
  • Have dry skin
  • Be forgetful
  • Feel depressed
  • Have constipation

Getting your thyroid back on track is critical. Thyroid problems increase your risk for:

  • High cholesterol and coronary artery disease.
  • Depression.
  • Reproductive problems, including infertility and miscarriage.
  • Goiter. Constant stimulation of an underactive thyroid can make the gland grow larger. A large "goiter" can make it hard to breathe or swallow.

Untreated hypothyroidism can also become life-threatening, especially in the elderly. If women with hypothyroidism are not treated during pregnancy, the development of the baby's nervous system may be affected.

What causes hypothyroidism?
The most common cause for hypothyroidism is Hashimoto's thyroiditis. This is an autoimmune condition in which the body's own antibodies attack and destroy the thyroid gland. Other causes of hypothyroidism include:

  • Treatment for an overactive thyroid (hyperthyroidism). Treatment to slow thyroid hormone production can lead to hypothyroidism. Treatments for overactive thyroid might include surgery to remove the thyroid or other treatments that require lifelong thyroid hormone replacement.
  • Radiation to the neck. Radiation to treat head and neck cancer, breast cancer or Hodgkin's disease can lead to hypothyroidism.
  • Certain drugs. These include amiodarone and interferon. These can affect the thyroid's ability to produce hormone.  
  • Not enough iodine in the diet. This is the leading cause of hypothyroidism worldwide. The thyroid needs iodine to make thyroid hormone. Lack of iodine leads both to low thyroid hormone levels and an enlarged thyroid gland (goiter). Hypothyroidism due to iodine deficiency is rare in the U.S. because there is enough iodine in the diet.
  • Pituitary gland damage. The pituitary gland tells the thyroid how much hormone to make. Tumor, radiation or surgery can damage the pituitary gland and the thyroid may not make enough hormone.
  • Thyroiditis. Inflammation of the thyroid gland after certain viral infections can lead to temporary hyperthyroidism followed by hypothyroidism.

The doctor visit for a thyroid problem
Your doctor will start by taking a medical history. Tell your doctor about any symptoms. Bring in your medications, both prescription and over-the-counter.

Your doctor may examine your thyroid and may also check your heart rate and reflexes. Your thyroid gland could be of normal size. Or it may be enlarged and/or tender.

Based on your medical history and examination, your doctor will decide what tests you need. Tests include:

  • TSH (thyroid stimulating hormone). TSH is secreted from the pituitary gland, a tiny gland under the brain, which drives the thyroid gland. A normal TSH value is between 0.3 and 3. A TSH above 3 means the thyroid is underactive. The thyroid is being stimulated to make hormone because there is not enough in circulation.
  • Thyroid hormones. The thyroid makes two hormones: T4 and T3. Low levels of these hormones in the blood confirm that the thyroid is underactive.
  • Thyroid antibody tests. If your doctor suspects Hashimoto's thyroiditis, your doctor will do a blood test for the antibody that causes this disease.

How is hypothyroidism treated?
Hypothyroidism cannot be cured. But, it can usually be treated by replacing the thyroid hormone that your thyroid gland is not making. If you are diagnosed with hypothyroidism, you will probably start taking the thyroid hormone medication levothyroxine (Synthroid). You will likely have to take this medicine for the rest of your life.

Your doctor will determine the dose based on your age, weight and other medical conditions. You will likely start on a low dose. Your doctor will adjust the dose until he or she finds the best dose for you. The only danger of thyroid hormone replacement is not taking enough or taking too much. If you are on hormone replacement therapy, your doctor will monitor your treatment and adjust your thyroid medication if needed.

When should I see my doctor for hypothyroidism?
Continue to see your doctor if you are on thyroid hormone. You will need to have your thyroid hormone level monitored. You should also see your doctor for the following reasons:

  • You gain or lose a lot of weight
  • Your symptoms of hypothyroidism return
  • You develop symptoms of hypothyroidism
By Louis Neipris, MD, Staff Writer
Created on 03/11/2003
Updated on 04/03/2009
  • American Thyroid Association. Hypothyroidism.
  • National Endocrine and Metabolic Disease Information Service. Hypothyroidism.
  • Ferri FF. Hypothyroidism. In: Ferri: Ferri's Clinical Advisor 2009, 1st ed. Philadelphia, PA: Mosby Elsevier; 2009.
  • U.S. Food and Drug Administration. Thyroid Medications: Q & A with Mary Parks, M.D.
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