Debra Fulghum Bruce, PhD
Mikio A. Nihira, MD
Feeling all revved up, even at bedtime? Or maybe your throttle's on idle with symptoms of depression, fatigue, and weight gain. In both cases, the root cause may be your thyroid.
The thyroid -- a butterfly-shaped gland in the front of your neck -- makes hormones that control the way your body uses energy. Your thyroid controls your metabolism, which is how your body turns food into energy, and also affects your heart, muscles, bones, and cholesterol.
While thyroid disorders can range from a small, harmless goiter (enlarged gland) to life-threatening cancer, the most common thyroid problems involve an abnormal production of thyroid hormones. If there is too much of these vital body chemicals, the result is a condition known as hyperthyroidism. Too little hormone production leads to hypothyroidism.
Although the effects of thyroid problems are unpleasant or uncomfortable, most thyroid conditions can be managed well if properly diagnosed and treated.
Hyperthyroidism happens when the thyroid becomes overactive and produces too much of its hormones. Hyperthyroidism affects women five times to 10 times more often than men, and is most common in people younger than 40. People with hyperthyroidism have problems that reflect over activity of the body's organs, resulting in such symptoms as sweating, feeling hot, rapid heartbeat, weight loss, and sometimes eye problems.
Hyperthyroidism can occur in several ways:
Graves' disease: The release of excess hormones is triggered by an autoimmune disorder. For some unknown reason, the body attacks the thyroid, causing it to spill out too much hormone.
Toxic adenomas: Nodules (abnormal growths or lumps) develop in the thyroid gland and begin to secrete thyroid hormones, upsetting the body's chemical balance. Some goiters may contain several of these nodules.
Subacute thyroiditis: Painful inflammation of the thyroid causes the gland to enlarge and "leak" excess hormones, resulting in temporary hyperthyroidism, which resolves spontaneously. Subacute thyroiditis generally lasts a few weeks but may persist for months.
Pituitary gland malfunctions or cancerous growths in the thyroid gland: Although rare, hyperthyroidism can also develop from these causes.
Silent thyroiditis: This is usually a temporary state of excess thyroid hormone release causing mild hyperthyroidism. In some cases it can result in permanent damage to the thyroid and low thyroid hormone production by the gland.
Postpartum thyroiditis: This is a type of hyperthyroidism that occurs in a small percentage of women within months of delivery. It last only a few months, followed by several months of reduced amounts of thyroid hormone production by the gland. Typically these women fully recover normal thyroid function.
Ingestion of excess thyroid hormone can result in hyperthyroidism.
Hypothyroidism, by contrast, stems from an underproduction of thyroid hormones. Since your body's energy production requires certain amounts of thyroid hormones, a drop in hormone production leads to lower energy levels, causing you to feel weak and tired.
Approximately 25 million people suffer with hypothyroidism and about half are undiagnosed. Older adults -- particularly women -- are more likely to develop hypothyroidism than younger adults. Hypothyroidism also tends to run in families.
If hypothyroidism is not treated, it can raise your cholesterol levels and make you more likely to have a heart attack or stroke. During pregnancy, untreated hypothyroidism can harm your baby. Luckily, hypothyroidism is easy to treat.
Causes of hypothyroidism may include:
Hashimoto's thyroiditis: In this autoimmune disorder, the body attacks thyroid tissue. The tissue eventually dies and stops producing hormones. Other autoimmune disorders occur with this condition and other family members may also be affected by this condition.
Removal of the thyroid gland: The thyroid may be surgically removed or chemically destroyed as treatment for hyperthyroidism.
Exposure to excessive amounts of iodide: The heart medicine amiodarone may expose you to too much iodine. Radioactive iodine treatment for hyperthyroidism can also result in hypothyroidism. You may be at greater risk for developing hypothyroidism, especially if you have had thyroid problems in the past.
Lithium: This drug has also been linked as a cause of hypothyroidism.
If left untreated for a long period of time, hypothyroidism can bring on a myxedema coma, a rare but potentially fatal condition that requires immediate hormone injections.
Your doctor will ask you about your symptoms and do a physical exam. Then he or she will order blood tests to see how much thyroid hormone your body is making. In addition, your doctor may discover that you have hyperthyroidism while doing a test for another reason.
Signs and Symptoms:
Symptoms of hypothyroidism occur slowly over time. At first you might not notice these symptoms. Or you might mistake them for normal aging. This is not normal aging. See your doctor if you have symptoms like these that get worse or won't go away.
Pregnancy, which requires an increased production of thyroid hormone, can cause hypothyroidism. About 2% of pregnant women in the United States get hypothyroidism.
Hyperthyroidism is easily treated. With treatment, you can lead a healthy life. Without treatment, hyperthyroidism can lead to serious heart problems, bone problems, and a dangerous condition called thyroid storm.
If your symptoms bother you, your doctor may give you pills called beta-blockers. These can help you feel better while you and your doctor decide what your treatment should be. Even if your symptoms do not bother you, you still need treatment because hyperthyroidism can lead to more serious problems.
Radioactive iodine and anti-thyroid medicine are the treatments doctors use most often. The best treatment for you will depend on a number of things, including your age. Some people need more than one kind of treatment.
After treatment, you will need regular blood tests. These tests check to see if your hyperthyroidism has come back. They also check to see if you are making enough thyroid hormone. Sometimes treatment cures hyperthyroidism but causes the opposite problem-too little thyroid hormone. If this happens, you may need to take thyroid hormone pills for the rest of your life.
Doctors usually prescribe thyroid hormone pills to treat hypothyroidism. Most people start to feel better within a week or two. Your symptoms will probably go away within a few months. But you will likely need to keep taking the pills for the rest of your life.
In most cases, thyroid hormone medication works quickly to correct symptoms. People with hypothyroidism who take thyroid hormone medication usually notice:
It's important to take your medicine just the way your doctor tells you to. You will also need to see your doctor for follow-up visits to make sure you have the right dose. Getting too much or too little thyroid hormone can cause problems.
If you have mild (subclinical) hypothyroidism, you may not need treatment now. But you'll want to watch closely for signs that it is getting worse.
According to the American Association of Clinical Endocrinologists (AACE), millions of women with unresolved menopausal-like symptoms, even those taking estrogen, may be suffering from undiagnosed thyroid disease. While symptoms such as fatigue, depression, mood swings, and sleep disturbances are frequently associated with menopause, they may also be signs of hypothyroidism.
A survey done by the AACE showed that only one in four women who have discussed menopause and its symptoms with a physician was also tested for thyroid disease. The thyroid plays a role in regulating overall body metabolism and influences the heart, brain, kidney, and reproductive system, along with muscle strength and appetite.
If you are experiencing symptoms of menopause and the symptoms persist despite appropriate therapy, ask your doctor to do a thyroid screen (TSH). A blood sample is all that is needed to make the initial diagnosis of hypothyroidism and treatment is easily achieved with thyroid replacement therapy.
Cancer of the thyroid gland is quite rare and occurs in less than 10% of thyroid nodules. You might have one or more thyroid nodules for several years before they are determined to be cancerous. People who have received radiation treatment to the head and neck earlier in life, possibly as a remedy for acne, tend to have a higher-than-normal propensity for thyroid cancer.
Some people may not have any symptoms. Their doctors may find a lump or nodule in the neck during a routine physical exam.
Most people who have treatment for thyroid cancer do very well, because the cancer is usually found early and the treatments, including surgery, work well. Once treated, thyroid cancer rarely returns.
WebMD's Medical References: "Understanding Thyroid Problems: The Basics." "Thyroid and Menopause: Confusing the Symptoms." "Thyroid Storm."
WebMD's Medical References: "Hypothyroidism." "Hypothyroidism Cause." "Thyroid hormone medications for hypothyroidism." "Hyperthyroidism."
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