Hypothyroidism, or low thyroid activity, means your thyroid gland is not making enough hormones. The thyroid gland is located in the front of your neck, just below your Adam’s apple. It makes hormones that control metabolism, the pace of your body’s processes. Metabolism includes things like your heart rate and how quickly you burn calories. Women, especially those over 50, are more likely to have hypothyroidism than men are. If left untreated, hypothyroidism can cause obesity, joint pain, infertility and heart disease.
Hypothyroidism
Hypothyroidism
What is hypothyroidism?
What causes hypothyroidism?
The most common cause of hypothyroidism is an autoimmune disease called Hashimoto’s thyroiditis. Normally, antibodies produced by the immune system help protect the body against viruses, bacteria and other foreign substances. An autoimmune disease is when your immune system produces antibodies that attack your body's tissues and/or organs. With Hashimoto’s thyroiditis, antibodies attack the thyroid and keep it from producing enough hormones.
Other common causes of hypothyroidism include:
Other common causes of hypothyroidism include:
- Treatment for hyperthyroidism, the condition in which the body produces too much thyroid hormone
- Radiation therapy
- Thyroid surgery
- Certain medicines
Some less common causes of hypothyroidism include:
- Congenital disease: About 1 in 3,000 infants in the United States are born with a defective thyroid or no thyroid at all. Most states require doctors to screen newborns for thyroid problems.
- Pituitary disorder: The pituitary gland produces a thyroid-stimulating hormone, which tells the thyroid gland how much thyroid hormone to produce. A pituitary disorder may keep the pituitary gland from producing the right amount of thyroid-stimulating hormone.
- Pregnancy: Some women develop hypothyroidism during or after pregnancy because their bodies produce antibodies that attack the thyroid gland. If it is not treated, hypothyroidism can jeopardize the health of both mother and baby.
- Iodine deficiency: Iodine is a mineral used by the body to make thyroid hormones. Iodine deficiency can keep the body from being able to make enough thyroid hormone. In the United States, table salt has iodine added to it to make sure everyone gets enough.
You have an increased risk of developing hypothyroidism if you:
- Have a close relative with an autoimmune disease
- Have been treated with radioactive iodine or anti-thyroid medicines
- Have received radiation therapy to your neck or upper chest
- Have had thyroid surgery in the past
What are the symptoms of hypothyroidism?
The symptoms of hypothyroidism tend to develop slowly. They can be different from case to case. Initial symptoms include slight fatigue and sluggishness. As your metabolism slows, you may develop other symptoms:
- Increased sensitivity to cold
- Constipation
- Pale, dry skin
- Puffy face
- Hoarse voice
- Elevated blood cholesterol
- Unexpected weight gain
- Muscle aches, cramps, tenderness or stiffness
- Pain, stiffness or swelling in your joints
- Heavier than normal menstrual periods in women
- Depression
- Visibly enlarged thyroid
- Brittle hair and fingernails
- Forgetfulness
Can children have hypothyroidism?
Anyone can develop the condition, including infants and teenagers.
Babies born without a thyroid gland or with a thyroid that doesn’t work properly don’t have many symptoms at first. They may have yellowing of the skin and the whites of their eyes (jaundice), a puffy face, frequent choking and a large tongue that sticks out slightly. As the disease progresses, infants may have trouble feeding and may not grow and develop normally. They may also be constipated, have poor muscle tone or be very sleepy. If it is not treated, hypothyroidism in infants can lead to physical and mental retardation. In the United States, newborn infants are screened for hypothyroidism before leaving the hospital.
Children and teens who develop hypothyroidism have the same symptoms as adults, but they may also experience:
Babies born without a thyroid gland or with a thyroid that doesn’t work properly don’t have many symptoms at first. They may have yellowing of the skin and the whites of their eyes (jaundice), a puffy face, frequent choking and a large tongue that sticks out slightly. As the disease progresses, infants may have trouble feeding and may not grow and develop normally. They may also be constipated, have poor muscle tone or be very sleepy. If it is not treated, hypothyroidism in infants can lead to physical and mental retardation. In the United States, newborn infants are screened for hypothyroidism before leaving the hospital.
Children and teens who develop hypothyroidism have the same symptoms as adults, but they may also experience:
- Very slow growth
- Delayed development of permanent teeth
- Delayed puberty
- Slow mental development
How will my doctor know I have hypothyroidism?
If you have symptoms of an underactive thyroid, your doctor will do tests that measure the levels of thyroid hormone and thyroid-stimulating hormone in your blood.
Some doctors recommend screening older women for hypothyroidism during routine physical examinations. Some also recommend screening pregnant women and women who are thinking about becoming pregnant.
Some doctors recommend screening older women for hypothyroidism during routine physical examinations. Some also recommend screening pregnant women and women who are thinking about becoming pregnant.
Are there any complications I should know about?
If it is not treated, hypothyroidism can lead to other health problems. These include:
- Goiter: Hypothyroidism can cause your thyroid to become larger, creating a swollen lump on your neck called a goiter. A goiter can affect your appearance and can even make it hard for you to swallow or eat.
- An increased risk of heart disease: An underactive thyroid causes high levels of “bad” (LDL) cholesterol.
- Mental health issues. Depression that occurs with hypothyroidism can become worse over time, especially if left untreated.
- Myxedema: A rare, life-threatening condition characterized by intense sensitivity to cold, drowsiness followed by severe sluggishness, leading to unconsciousness and even coma.
- Birth defects: Babies born to women who have untreated hypothyroidism may have birth defects.
- Infertility. Low hormone levels can make it difficult for a woman who has hypothyroidism to become pregnant.
How is hypothyroidism treated?
Treatment for an underactive thyroid is synthetic thyroid hormone taken daily in pill form. This medicine will regulate hormone levels and shift your metabolism back to normal. It will also lower your LDL cholesterol and may help reverse weight gain. It may take a few tries to get the right dose of synthetic thyroid hormone. If you are not taking enough, you may continue to experience symptoms of hypothyroidism. If you are taking too much, you may have symptoms similar to those of hyperthyroidism (overactive thyroid disease). Your doctor can tell if you are taking the right dose of thyroid hormone based on how you feel, by examination and by blood testing.
Some medicines, supplements and foods may affect your body’s ability to absorb the synthetic thyroid hormone. Tell your doctor if you eat large amounts of soy products, are on a high-fiber diet or take other medicines such as iron supplements, calcium supplements, cholestyramine or aluminum hydroxide (found in some antacids).
Some medicines, supplements and foods may affect your body’s ability to absorb the synthetic thyroid hormone. Tell your doctor if you eat large amounts of soy products, are on a high-fiber diet or take other medicines such as iron supplements, calcium supplements, cholestyramine or aluminum hydroxide (found in some antacids).
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Written by familydoctor.org editorial staff.
American Academy of Family Physicians
Reviewed/Updated: 03/09
Created: 09/07