Your thyroid is a butterfly-shaped gland located at the base of your neck, just below your Adam's apple. Although it weighs less than an ounce, the thyroid gland has an enormous effect on your health. All aspects of your metabolism, from the rate at which your heart beats to how quickly you burn calories, are regulated by thyroid hormones.

As long as your thyroid releases the proper amounts of these hormones, your system functions normally. But sometimes your thyroid doesn't produce enough hormones, upsetting the delicate balance of chemical reactions in your body. This condition is known as hypothyroidism.

Signs and symptoms

The signs and symptoms of hypothyroidism vary widely, depending on the severity of the hormone deficiency. But in general, any problems you do have tend to develop slowly, often over a number of years.

At first, you may barely notice symptoms such as fatigue and sluggishness, or you may simply attribute them to getting older.

• Cold

• Depression

• Fatigue

But as your metabolism continues to slow, you may develop more obvious signs and symptoms, including:

• Increased sensitivity to cold.

• Constipation.

• Pale, dry skin.

• A puffy face.

• Hoarse voice.

• An elevated blood cholesterol level.

• Unexplained weight gain. Many people attribute their weight gain to an underactive thyroid, but this is true only in a few cases. Hypothyroidism will rarely cause you to gain more than 10 to 20 pounds — most of which is fluid.

• Muscle aches, tenderness and stiffness, especially in your shoulders and hips.

• Pain and stiffness in your joints and swelling in your knees or the small joints in your hands and feet.

• Muscle weakness, especially in your lower extremities.

• Heavier than normal menstrual periods.

• Depression.

When hypothyroidism isn't treated, symptoms can gradually become more severe. Constant stimulation of your thyroid to release more hormones may lead to an enlarged thyroid (goiter). In addition, you may become more forgetful, your thought processes may slow or you may feel depressed.

Advanced hypothyroidism, known as myxedema, is rare, but when it occurs it can be life-threatening. Symptoms include drowsiness and intense intolerance to cold followed by profound lethargy and unconsciousness. In some cases, myxedema can be fatal.

• Cold

• Goiter

• Hypothyroidism – Prevention

• Hypothyroidism – Natural Remedies

• Symptoms and Causes of Hypothyroidism

Hypothyroidism in children and teens
Although hypothyroidism most often affects middle-aged and older women, anyone can develop the condition, including infants and teenagers. Initially, babies born without a thyroid gland or with a gland that doesn't work properly may have few signs and symptoms. When newborns do have problems, they may include:

• Yellowing of the skin and whites of the eyes (jaundice). In most cases, this occurs when a baby's liver can't metabolize a molecule called bilirubin, which normally forms when the body recycles old or damaged red blood cells.

• Noisy breathing.

• A large, protruding tongue.

As the disease progresses, infants are likely to have trouble feeding and may fail to grow and develop normally. They may also have:

• Rough, dry skin

• Constipation

• Poor muscle tone

• Excessive sleepiness

Left untreated, even mild hypothyroidism in infants can lead to severe physical and mental retardation.

In general, children and teens who develop hypothyroidism have the same signs and symptoms as adults do, but they may also experience:

• Poor growth, resulting in short stature

• Delayed development of permanent teeth

• Delayed puberty

• Difficulty in school

Causes

Your thyroid gland produces two main hormones, thyroxine (T-4) and triiodothyronine (T-3). They maintain the rate at which your body uses fats and carbohydrates, help control your body temperature, influence your heart rate and help regulate the production of protein. Your thyroid gland also produces calcitonin, a hormone that regulates the amount of calcium in your blood.

The rate at which thyroxine and triiodothyronine are released is controlled by your pituitary gland and your hypothalamus — an area at the base of your brain that acts as a thermostat for your whole system. Here's how the process works:

The hypothalamus signals your pituitary gland to make a hormone called thyroid-stimulating hormone (TSH). Your pituitary gland then releases TSH — the amount depends on how much thyroxine and triiodothyronine are in your blood. Finally, your thyroid gland regulates its production of hormones based on the amount of TSH it receives.

Although this process usually works well, the thyroid sometimes fails to produce enough hormones. This may be due to a number of different factors, including:

• Autoimmune disease (Hashimoto's thyroiditis). Autoimmune disorders occur when your immune system produces antibodies that attack your own tissues. Sometimes this process occurs within the thyroid gland. Scientists aren't sure why the body produces antibodies against itself. Some think a virus or bacteria might trigger the response, while others believe a genetic flaw may be involved. Most likely, autoimmune diseases result from more than one factor. But however it happens, these antibodies affect the thyroid's ability to produce hormones.

• Treatment with radioactive iodine. The most common treatment for people who produce too much thyroid hormone (hyperthyroidism) is radioactive iodine. The radioactive material becomes concentrated in the thyroid gland, reducing its function. Often, however, function is reduced too much, resulting in hypothyroidism. Anti-thyroid drugs such as methimazole (Tapazole) — also used to treat conditions in which the thyroid produces too much thyroid hormone — may cause hypothyroidism as well.

• Radiation therapy. Radiation used to treat cancers of the head and neck can affect your thyroid gland and may lead to hypothyroidism.

• Thyroid surgery. Removing all or a large portion of your thyroid can diminish or halt hormone production. In that case, you'll need to take thyroid hormones for life.

• Medications. A number of medications can contribute to hypothyroidism. One of the most common is lithium, which is used to treat certain psychiatric disorders. If you're taking medication, ask your doctor about its effect on your thyroid gland.

Less often, hypothyroidism may result from one of the following:

• Congenital disease. In most cases, the thyroid gland didn't develop normally for unknown reasons, but some children have an inherited form of the disorder. Often, infants with congenital hypothyroidism appear normal at birth. That's one reason why doctors now recommend that all newborns receive thyroid tests when they're between 24 and 72 hours old.

• Pituitary disorder. About 1 percent of cases of hypothyroidism are caused by the failure of the pituitary gland to produce enough TSH — usually due to a benign tumor of the pituitary gland.

• Pregnancy. Some women develop hypothyroidism during or after pregnancy (postpartum hypothyroidism), often because they produce antibodies to their own thyroid gland. Left untreated, hypothyroidism increases the risk of miscarriage, premature delivery and preeclampsia — a condition that causes a significant rise in a woman's blood pressure during the last three months of pregnancy. It can also seriously affect the developing fetus.

• Iodine deficiency. The trace mineral iodine — found primarily in seafood, seaweed, plants grown in iodine-rich soil and iodized salt — is essential for the production of thyroid hormones. Before the 1920s, it wasn't unusual for people to develop hypothyroidism because they consumed too little of this mineral. In other parts of the world, however, as many as 200 million people may have iodine deficiencies.

Risk factors

Although anyone can develop hypothyroidism, it occurs mainly in women older than 40, and the risk of developing the disorder increases with age. You also have an increased risk if you:

• Have a close relative, such as a parent or grandparent, with an autoimmune disease

• Have diabetes, which moderately increases the risk that you'll develop hypothyroidism during or after pregnancy

• Have been treated with radioactive iodine or anti-thyroid medications

• Received radiation to your neck or upper chest, even if the treatment occurred years ago

• Have had thyroid surgery (thyroidectomy)

When to seek medical advice

See your doctor if you're feeling tired for no reason or have any of the other symptoms of hypothyroidism, such as dry skin, a pale, puffy face, constipation or a hoarse voice.

• constipation

• High Blood Cholesterol

You'll also need to see your doctor for periodic testing of your thyroid function if you've had previous thyroid surgery, treatment with radioactive iodine or anti-thyroid medications, or radiation therapy to your head, neck or upper chest.

If you have high blood cholesterol, talk to your doctor about whether hypothyroidism may be a cause. And if you're receiving hormone therapy for hypothyroidism, schedule follow-up visits as often as your doctor recommends. Initially, it's important to make sure you're receiving the correct dose of medicine. And over time, the dose you need to keep your thyroid functioning normally may change.

To learn about ways to cure this condition continue reading.

• Hypothyroidism – Prevention

• Hypothyroidism – Natural Remedies

• Symptoms and Causes of Hypothyroidism