What is Hypothyroidism?

Hypothyroidism (underactive thyroid) is a condition in which your thyroid gland doesn't produce enough of certain important hormones.

Women, especially those older than age 50, are more likely to have hypothyroidism. Hypothyroidism upsets the normal balance of chemical reactions in your body. It seldom causes symptoms in the early stages, but, over time, untreated hypothyroidism can cause a number of health problems, such as obesity, joint pain, infertility and heart disease. The good news is that accurate thyroid function tests are available to diagnose hypothyroidism, and treatment of hypothyroidism with synthetic thyroid hormone is usually simple, safe and effective once the proper dosage is established.

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 the symptoms of hypothyroidism, such as fatigue and sluggishness, or you may simply attribute them to getting older. But as your metabolism continues to slow, you may develop more obvious signs and symptoms. Hypothyroidism signs and symptom may include:

1) Fatigue
2) Sluggishness
3) Increased sensitivity to cold
4) Constipation
5) Pale, dry skin
6) A puffy face
7) Hoarse voice
8) An elevated blood cholesterol level
9) Unexplained weight gain
10) Muscle aches, tenderness and stiffness
11) Pain, stiffness or swelling in your joints
12) Muscle weakness
13) Heavier than normal menstrual periods
14) Brittle fingernails and hair
15) Depression

When hypothyroidism isn't treated, signs and 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. Signs and symptoms include low blood pressure, decreased breathing, decreased body temperature, unresponsiveness and even coma. In extreme cases, myxedema can be fatal.

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 with hypothyroidism, 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 substance called bilirubin, which normally forms when the body recycles old or damaged red blood cells.

1) Frequent choking.
2) A large, protruding tongue.
3) A puffy appearance to the face.

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

1) Constipation
2) Poor muscle tone
3) Excessive sleepiness

When hypothyroidism in infants is not treated, even mild cases 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:

1) Poor growth, resulting in short stature
2) Delayed development of permanent teeth
3) Delayed puberty
4) Poor mental development

Causes

When your thyroid doesn't produce enough hormones, the balance of chemical reactions in your body can be upset. There can be a number of causes, including autoimmune disease, treatment for hyperthyroidism, radiation therapy, thyroid surgery and certain medications.

Your thyroid is a small, butterfly-shaped gland located at the base of the front of your neck, just below your Adam's apple. Hormones produced by the thyroid gland have an enormous impact on your health, affecting all aspects of your metabolism.

Two main hormones

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 T-4 and T-3 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. 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 T-4 and T-3 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. Hypothyroidism may be due to a number of different factors, including:

Autoimmune disease. People who develop a particular inflammatory disorder known as Hashimoto;s thyroiditis suffer from the most common cause of hypothyroidism. Autoimmune disorders occur when your immune system produces antibodies that attack your own tissues. Sometimes this process involves your thyroid gland. Scientists
aren't sure why the body produces antibodies against itself. Some think a virus or bacterium 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 for hyperthyroidism. People who produce too much thyroid hormone (hyperthyroidism) are often treated with radioactive iodine or anti-thyroid medications to reduce and normalize their thyroid function. However, in some cases, treatment of hyperthyroidism can result in permanent hypothyroidism.

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 gland can diminish or halt hormone production. In that case, you'll need to take thyroid hormone for life.

Medications. A number of medications can contribute to hypothyroidism. One such medication 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. Approximately 1 in 3,000 babies in the United States is born with a defective thyroid gland or no thyroid gland at all. 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 most states now require newborn thyroid screening.

Pituitary disorder. A relatively rare cause of hypothyroidism is the failure of the pituitary gland to produce enough TSH, usually because of 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. In some parts of the world, iodine deficiency is common, but the addition of iodine to table salt has virtually eliminated this problem in the United States.

Western Medicine Treatment

Standard treatment for hypothyroidism involves daily use of the synthetic thyroid hormone levothyroxine (Levothroid, Synthroid, others). This oral medication restores adequate hormone levels, shifting your body back into normal gear. One to two weeks after starting treatment, you'll notice that you're feeling less fatigued. The medication also gradually lowers cholesterol levels elevated by the disease and may reverse any weight gain. Treatment with levothyroxine is usually lifelong, but because the dosage you need may change, your doctor is likely to check your TSH level every year. Determining proper dosage may take time.

To determine the right dosage of levothyroxine initially, your doctor generally checks your level of TSH after two to three months. Excessive amounts of the hormone can cause side effects, such as:

1) Increased appetite
2) Insomnia
3) Heart palpitations
4) Shakiness

If you have coronary artery disease or severe hypothyroidism, your doctor may start treatment with a smaller amount of medication and gradually increase the dosage. Progressive hormone replacement allows your heart to adjust to the increase in metabolism.

Levothyroxine causes virtually no side effects when used in the appropriate dose and is relatively inexpensive. If you change brands, let your doctor know to ensure you're still receiving the right dosage. Also, don't skip doses or stop taking the drug because you're feeling better. If you do, the symptoms of hypothyroidism will gradually return.

Proper absorption of levothyroxine

Certain medications, supplements and even some foods may affect your ability to absorb levothyroxine. Talk to your doctor if you eat large amounts of soy products or a high-fiber diet or you take other medications, such as:

1) Iron supplements
2) Cholestyramine
3) Aluminum hydroxide, which is found in some antacids
4) Calcium supplements

If you have subclinical hypothyroidism, discuss treatment with your doctor. For a relatively mild increase in TSH, you probably won't benefit from thyroid hormone therapy, and treatment could even be harmful. On the other hand, for a higher TSH level, thyroid hormones may improve your cholesterol level, the pumping ability of your heart and your energy level.

Adopted from mayoclinic.com