This topic provides information about hypothyroidism. Hypothyroidism means your thyroid is not making enough thyroid hormone. If you are looking for information about when the thyroid makes too much thyroid hormone, see the topic Hyperthyroidism.
Hypothyroidism means your thyroid is not making enough thyroid hormone. The thyroid is a butterfly-shaped gland in the front of your neck. It makes hormones that control the way your body uses energy.
Having a low level of thyroid hormone affects your whole body. It can make you feel tired and weak. If hypothyroidism is not treated, it can raise your cholesterol levels. During pregnancy, untreated hypothyroidism can harm your baby. But hypothyroidism can be treated with medicine that can help you feel like yourself again.
People of any age can get hypothyroidism, but older adults are more likely to get it. Women age 60 and older have the highest risk. You are more likely to get the disease if it runs in your family.
In the United States, the most common cause is Hashimoto's thyroiditis. It causes the body's immune system to attack thyroid tissue. As a result, the gland can't make enough thyroid hormone.
Other things that can lead to low levels of thyroid hormone include surgery to remove the thyroid gland and radiation therapy for cancer. Less common causes include viral infections and some drugs, such as amiodarone and lithium.
Hypothyroidism can cause many different symptoms, such as:
- Feeling tired, weak, or depressed.
- Dry skin and brittle nails.
- Not being able to stand the cold.
- Memory problems or having trouble thinking clearly.
- Heavy or irregular menstrual periods.
Symptoms occur slowly over time. At first you might not notice them, or you might mistake them for normal aging. See your doctor if you have symptoms like these that get worse or won't go away.
Your doctor will ask questions about your symptoms. You will also have a physical exam. If your doctor thinks you have hypothyroidism, a simple blood test can show if your thyroid hormone level is too low.