Hypothyroidism
The butterfly-shaped thyroid gland is located just below your Adam's apple, at the front of your neck. This vital gland is part of the endocrine system and churns out hormones that dictate how your body uses energy — which is your metabolism — namely thyroxine (T4) and triiodothyronine (T3).
People whose bodies produce inadequate amounts of thyroid hormone develop hypothyroidism. Women are more prone to hypothyroidism than men, especially after the age of forty. Experts estimate that 20 million people in the United States have hypothyroidism.
The most common cause of hypothyroidism is an autoimmune condition called Hashimoto's thyroiditis, in which antibodies attack the thyroid and damage it, reducing its ability to produce hormones. Other causes include radiation treatments, medications, and thyroid surgery. Hypothyroidism may also be caused by a malfunction of the pituitary gland, which releases a hormone called thyroid-stimulating hormone (TSH). TSH regulates the production of thyroid hormones.
Symptoms and Diagnosis
Hypothyroidism typically causes fatigue, weakness, and joint or muscle pain, especially in the shoulders and hips. Women who have it are susceptible to depression and sensitive to the cold. They may also develop puffiness in the skin. Other symptoms include dry skin, brittle nails, hair loss, constipation, and irregular menstrual periods. Some women experience an increase in their cholesterol levels and gain weight.
Diagnosing hypothyroidism is based on a doctor's thorough examination as well as blood tests that measure levels of T4 and serum TSH in the blood. If your thyroid isn't making enough hormones, your pituitary will release more TSH in order to compensate for the shortfall.
Treatment
The goal in treating hypothyroidism is to restore the deficient hormone to its normal levels. To do that, patients are generally given additional thyroid hormone. You will receive treatment the rest of your life, but it's important to monitor your hormone levels. The dosage of your medications can vary, depending on changes in your hormones.
Alert
Women who have a hypothyroid have another reason to quit smoking. Studies show that women who smoke had higher levels of LDL, the bad cholesterol, as well as higher total cholesterol levels, both risks for heart disease. The smokers also had more muscle problems. Cigarette smoking apparently impairs the secretion and action of thyroid hormone.
How Hypothyroidism Differs from FMS
It's easy to see why hypothyroidism is sometimes confused with FMS. The widespread aches and fatigue are symptoms of both conditions. But simple blood tests that measure hormone levels can determine whether an underactive thyroid is the culprit. Interestingly, many people who thought they had fibromyalgia have seen their symptoms completely disappear when they were later diagnosed with and treated for hypothyroidism.

