What is Hypothyroidism?
Hypothyroidism, also called underactive thyroid, is a condition in which the thyroid gland does not produce enough hormone. Hypothyroidism can be caused by the autoimmune disorder Hashimoto’s thyroiditis, irradiation or surgical removal of the thyroid gland, and medications that reduce thyroid hormone levels. Anyone can develop hypothyroidism, but people who are most at risk include those who are over age 50 and female. However, only a small percentage of people have full-blown (overt) hypothyroidism. Many more have mildly underactive glands (subclinical hypothyroidism).
Symptoms of hypothyroidism include:
- Difficulty concentrating
- Feeling cold
- Muscle and joint aches
- Weight gain, despite diminished appetite
- Dry skin
- Coarse hair, hair loss
- Hoarse voice
- Menstrual irregularities (either heavier-than-normal or lighter-than-normal bleeding)
- Milky discharge from the breasts (galactorrhea)
Diagnosis and Treatment
Hypothyroidism can cause serious complications if left untreated. Fortunately, it can be easily diagnosed with blood tests that measure levels of the thyroid hormone thyroxine (T4) and thyroid-stimulating hormone (TSH). Your doctor may also want to test for antithyroid antibodies and check your cholesterol levels. Based on these test results, the doctor will decide whether to prescribe medication or simply have you get lab tests every 6 - 12 months.
The standard drug treatment for hypothyroidism is a daily dose of a synthetic thyroid hormone called levothyroxine. This drug helps normalize blood levels of T4, TSH, and a third hormone called triidothyronine(T3). Many prescription medications can interact with levothyroxine and either increase or decrease its potency. (Make sure your doctor knows all medications you are taking.) Large amounts of dietary fiber can also interfere with levothyroxine treatment. People who eat high-fiber diets may need higher doses of the drug.
Review Date: 05/03/2011
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.