The Thyroid Book Health Article

It doesn't look like much—a small, butterfly-shaped gland, just below your Adam's apple. But your thyroid gland has a big effect on the way your body works. The thyroid controls your body's energy level, and problems with your thyroid gland can interfere with your life. However, these problems can be treated. You and your doctor can discuss how best to handle your thyroid problem.

Problems with Your Thyroid

You may not hear much about thyroid problems, but they're common and affect many people. Having a thyroid problem may mean that your thyroid gland is underactive and doesn't work hard enough. Or, it may mean that your gland is overactive and works too hard. Your thyroid gland may also grow larger or develop lumps.

An Underactive Thyroid

When the thyroid doesn't work hard enough, it's called hypothyroidism. If you have hypothyroidism, your body runs more slowly and you have less energy. You may notice one or more of these symptoms:

• Feeling sluggish and tired

• Getting cold easily

• Gaining weight more easily

An Overactive Thyroid

When the thyroid works too hard, it's called hyperthyroidism. If you have hyperthyroidism, your body runs faster. You may notice one or more of these symptoms:

• Getting hot easily

• Feeling wired and jittery, but also burned out and tired

• Losing weight without dieting

Thyroid Nodules

Your thyroid gland may develop one or more small lumps. These lumps are called nodules. If you have nodules, your thyroid usually continues to work at the right pace. As a result, you may not have any symptoms, although you may be able to feel the nodule in your neck. Nodules are usually harmless, but occasionally they may be a sign of thyroid cancer.

Thyroid Problems Can Be Treated

Problems with the thyroid gland are often easy to treat. Even most forms of thyroid cancer are treatable, and the treatment often has a good outcome. Your doctor will evaluate your problem and discuss your treatment options with you. Depending on your type of problem, possible treatments include medications, thyroid hormone pills, surgery, and other procedures.

The Healthy Thyroid

Your thyroid gland may be small, but it has an important job. It regulates the rate at which every part of your body works. This is called your metabolism. When your thyroid is healthy, your metabolism stays at a steady pace, not too fast or too slow. A healthy thyroid keeps your body working right and keeps you feeling good.

Keeping Your Body Working Right

By controlling your metabolism, your thyroid helps keep your body working right. The speed of your metabolism affects the workings of your organs, such as your heart and brain. Your metabolism acts on your digestive system to control how efficiently you burn calories. It keeps your skin, hair, and nails healthy and your muscles and nerves in good condition. It can even influence how you think and feel. Your thyroid gland regulates your metabolism by making thyroid hormone — a chemical that carries messages from the thyroid to the rest of the body. Thyroid hormone travels through the bloodstream to your heart, skin, brain, and all the other parts of your body. It tells these parts of your body how fast to work.

Thyroid Hormone: The Thyroid's Messenger

Your thyroid gland makes thyroid hormone from iodine, which is absorbed from the food you eat. When a large amount of thyroid hormone is produced, the cells work faster. When less thyroid hormone is produced, the cells work slower. To control the amount of thyroid hormone that's produced, the pituitary gland monitors the level of thyroid hormone in your blood and tells the thyroid when it needs to make more.

The Pituitary Gland

The pituitary gland, a pea-sized gland at the base of your brain, controls how much hormone the thyroid makes. The pituitary gland produces thyroid stimulating hormone (TSH) if it senses that there's not enough thyroid hormone in the bloodstream. TSH then tells the thyroid to make more thyroid hormone. The pituitary gland produces TSH more slowly when it senses that enough thyroid hormone is in the bloodstream.

The Parathyroid Glands

Four parathyroid glands regulate the amount of calcium in the blood. These glands sit close to the underside of the thyroid gland.

Thyroid Hormone and TSH

In general, levels of thyroid stimulating hormone (TSH) in the bloodstream go up when there's less thyroid hormone and down when there's more thyroid hormone.

• With hypothyroidism, the thyroid produces less thyroid hormone than normal. This prompts the pituitary to send extra TSH into the bloodstream to try to get the thyroid to make more hormone.

• With hyperthyroidism, the thyroid produces more thyroid hormone than normal. The pituitary then cuts back on the amount of TSH it sends into the bloodstream.