Hypothyroidism

What is hypothyroidism?

Hypothyroidism is a lack of thyroid hormone. It develops when the thyroid gland does not produce enough of the hormone, which controls the way the body uses energy. A lack of thyroid hormone affects all body systems.

See an illustration of the thyroid gland .

The risk of developing hypothyroidism tends to increase with age; women older than 60 have the highest risk. In rare cases, hypothyroidism occurs in infants and children. Infants will grow and develop normally if hypothyroidism is treated within the first month of life. Untreated hypothyroidism in infants can cause brain damage, leading to mental retardation and developmental delays. Every state in the United States tests newborns for hypothyroidism.

Teens with hypothyroidism typically look much younger than their age. With proper treatment, a teen will catch up in weight and height to healthy teens of the same age.

In adults, untreated hypothyroidism can cause several complications, including fluid around the heart and an increase in the levels of cholesterol and triglycerides (increasing the risk of coronary artery disease and stroke). Severe hypothyroidism can cause a life-threatening condition called myxedema coma.

Whether untreated hypothyroidism gets better or worse depends on its cause and your age. Hypothyroidism caused by Hashimoto's thyroiditis will occasionally disappear on its own. Hashimoto's thyroiditis is a disease in which the body's natural defense (immune) system attacks the thyroid gland. More often, you will have a gradual loss of thyroid function.

Women may develop hypothyroidism during or after pregnancy. Hypothyroidism that developed before pregnancy may become worse during pregnancy.

What causes hypothyroidism?

Hashimoto's thyroiditis is the most common cause of hypothyroidism in the United States. Other common causes include surgical removal of the thyroid gland, radioactive iodine therapy, and thyroiditis after childbirth.

Less common causes include:

• Viral and bacterial infections of the thyroid gland.
• Problems with the pituitary gland or the hypothalamus (areas of the brain that produce hormones).
• Too little or too much iodine in the diet (rarely seen in Western countries).
• Some medicines, including lithium carbonate and interferon alfa.
• Congenital hypothyroidism (present from birth).

What are the symptoms?

The symptoms of hypothyroidism occur throughout the body. In adults, they usually develop slowly and are often mistaken for part of the aging process. Symptoms in adults may include:

• Coarse and thinning hair.
• Brittle nails.
• Dry skin.
• A yellowish tint to the skin.
• Slow body movements and speech.
• Inability to tolerate cold.
• Feeling tired, sluggish, or weak.
• Memory problems, depression, or difficulty concentrating.
• Constipation.
• Heavy or irregular menstrual periods that may last longer than 5 to 7 days.

Other, less common symptoms may include an enlarged thyroid gland (goiter), modest weight gain, a hoarse voice, muscle aches and cramps, a puffy face, and swelling of the arms, hands, legs, and feet.

How is hypothyroidism diagnosed?

A medical history and physical exam are the first steps in diagnosing hypothyroidism. If your health professional thinks you may have hypothyroidism, you will have blood tests to measure your thyroid hormones. If you have no symptoms or mild symptoms of hypothyroidism, and blood tests show slightly abnormal levels of thyroid hormone, you may have mild (subclinical) hypothyroidism.

How is it treated?

Hypothyroidism is treated with thyroid hormone medicine. Symptoms usually disappear within a few months after treatment begins. Most people who develop hypothyroidism need treatment for the rest of their lives.

Can I prevent it?

You cannot prevent hypothyroidism, but you can watch for signs of the disease so it can be treated promptly. Older adults, especially women older than 60, those with a strong family history of hypothyroidism, and those with Addison's disease, rheumatoid arthritis, pernicious anemia, or type 1 diabetes should be tested for hypothyroidism.

Expert groups differ on whether to recommend widespread screening for hypothyroidism. The American Thyroid Association recommends that all adults be tested beginning at age 35 and continuing every 5 years.¹

However, other groups say there is not enough evidence of benefit to recommend screening for everyone. But they do suggest that people who are high risk—women older than 60 and anyone with a family history of thyroid disease or who has other autoimmune diseases—may want to be screened.^{2, 3}

In the United States, the most common cause of hypothyroidism is Hashimoto's thyroiditis, a condition that causes the body's defenses—or immune system—to produce antibodies that over time destroy thyroid tissue. As a result, the thyroid gland cannot make enough thyroid hormone.

Worldwide, iodine deficiency is the number one cause of hypothyroidism. Iodine added to salt, food, and water has eliminated this problem in the United States and other Western countries.

Other common causes of hypothyroidism include:

• Thyroid surgery. Part or all of the thyroid gland may be removed to treat disorders such as having too much thyroid hormone (hyperthyroidism), an enlarged thyroid gland (goiter) that makes swallowing difficult, thyroid cancer, or thyroid nodules that may be overactive or cancerous. Hypothyroidism results when the thyroid gland is removed or when remaining thyroid tissue does not function properly.
• Radioactive iodine therapy, which is often used to treat hyperthyroidism. Radioactive iodine therapy can destroy the thyroid gland, leading to hypothyroidism.
• External beam radiation, which is used to treat some cancers, such as Hodgkin's lymphoma. This radiation treatment can destroy the thyroid gland.

Less common causes include:

• Infections. Viral and bacterial infections can temporarily damage the thyroid gland, causing a short-term form of the condition. Hypothyroidism caused by infection usually does not result in permanent hypothyroidism.
• Medicines. Some medicines can interfere with normal production of thyroid hormone. Lithium carbonate is one of the most common medicines that causes hypothyroidism. Others include amiodarone (such as Amiodarone, Cordarone, and Pacerone) and interferon alfa (such as Infergen, Rebetron, and Wellferon).
• In rare instances, disorders of the pituitary gland or the hypothalamus (secondary and tertiary forms of hypothyroidism). The pituitary gland and hypothalamus produce hormones that control the thyroid and, as a result, affect its ability to produce thyroid hormone.
• Excessive iodine, which, in food or medicines, can reduce the function of the thyroid gland. This is usually temporary.
• Congenital hypothyroidism. About 1 in 4,000 infants is born without a properly functioning thyroid gland. All children born in a hospital in the United States are tested at birth for hypothyroidism.⁴

Mild (subclinical) hypothyroidism is most often caused by inadequate treatment of hypothyroidism, Hashimoto's thyroiditis, or radioactive iodine therapy.⁵ However, it may be caused by anything that causes hypothyroidism.

Pregnancy, which requires an increased production of thyroid hormone, can cause hypothyroidism. About 2% of pregnant women in the United States get hypothyroidism.⁶

Symptoms of hypothyroidism usually appear slowly over months or years. Symptoms and signs may include:

• Coarse and thinning hair.
• Dry skin.
• Brittle nails.
• A yellowish tint to the skin.
• Slow body movements.
• Cold skin.
• Inability to tolerate cold.
• Feeling tired, sluggish, or weak.
• Memory problems, depression, or difficulty concentrating.
• Constipation.
• Heavy or irregular menstrual periods that may last longer than 5 to 7 days.

Other, less common symptoms may include:

• An enlarged thyroid gland (goiter).
• Modest weight gain, often 10 lb (4.5 kg) or less.
• Swelling of the arms, hands, legs, and feet, and facial puffiness, particularly around the eyes.
• Hoarseness.
• Muscle aches and cramps.

In general, how bad your symptoms are depends on your age, how long you have had hypothyroidism, and the seriousness of the condition. The symptoms may be so mild and happen so slowly that they go unnoticed for years. The older you are, the more likely you are to notice symptoms.

Mild (subclinical) hypothyroidism often causes no symptoms or vague symptoms that may be attributed to aging, such as memory problems, dry skin, and fatigue.

Symptoms of hypothyroidism during and after pregnancy include fatigue, weight loss, dizziness, depression, and memory and concentration problems. Some women develop a goiter.

Because of the variety of symptoms, hypothyroidism can be mistaken for depression, especially during and after pregnancy. In older people, it may be confused with Alzheimer's disease, dementia, and other conditions that cause memory problems.

Symptoms of hypothyroidism in infants, children, and teens

Although rare, hypothyroidism can occur in infants, children, and teens. In infants, symptoms of a goiter include a poor appetite and choking on food. Symptoms of hypothyroidism may include dry, scaly skin. In children and teens, symptoms include behavior problems and changes in school performance. Children and teens may gain weight and yet have a slowed growth rate. Teens may have delayed puberty and look much younger than their age.

Untreated hypothyroidism may get better or worse over time, depending on its cause and your age.

Hypothyroidism in infants and children

Although rare, hypothyroidism can occur in infants and children. If hypothyroidism is treated within the first month of life, a child will grow and develop normally. Untreated hypothyroidism in infants can cause brain damage, leading to mental retardation and developmental delays. In the United States, all children are tested for hypothyroidism at birth.

Mental retardation usually does not occur if hypothyroidism develops after age 3. However, untreated childhood hypothyroidism typically delays physical growth and sexual development, including the onset of puberty. Children may gain weight yet have a slowed growth rate.

Hypothyroidism in adults

Hypothyroidism caused by Hashimoto's thyroiditis occasionally will disappear on its own. More often, the disorder causes a gradual loss of thyroid function, so your symptoms may develop slowly and be so mild that you do not notice them for years. However, symptoms usually grow worse, and health problems may develop as the disease continues.

If untreated, hypothyroidism may lead to:

• Myxedema, a condition that causes swelling of tissues, increased fluid around the heart and lungs, slowed muscle reflexes, and a slowed ability to think.
• Myxedema coma, a rare, life-threatening condition. This can occur if you have had hypothyroidism for many years that becomes markedly worse. It usually occurs when older adults who have severe hypothyroidism become ill with another condition, suffer from cold exposure, or take painkillers or sleeping pills. Symptoms include mental deterioration, such as apathy, confusion, and psychosis. You may lose consciousness (coma) and may have an extremely low body temperature (hypothermia), slow heartbeat (fewer than 60 beats per minute), heart failure, and difficulty breathing.
• Complications, such as:
  • Increased levels of cholesterol and triglycerides (increasing the risk of coronary artery disease and stroke).
  • Fluid around the heart (pericardial effusion).
  • Sleep apnea, which causes you to stop breathing for 10 seconds or longer while sleeping.
  • Forgetfulness and dementia.

People with mild (subclinical) hypothyroidism have only slightly abnormal thyroid blood test results and often do not have obvious symptoms or health problems. Some people with mild hypothyroidism regain normal thyroid function, but every year about 2% to 5% of people with subclinical disease develop hypothyroidism; about 20% of women older than 60 have subclinical hypothyroidism.³

If your thyroid gland has been removed during surgery, hypothyroidism will occur within a few weeks. If you have been treated with radioactive iodine therapy, hypothyroidism may develop within a year.⁵ In these cases, thyroid function generally does not return, and you have to take thyroid hormone medicine for the rest of your life.

Hypothyroidism during and after pregnancy

Women who have hypothyroidism or mild hypothyroidism before they become pregnant may develop more severe hypothyroidism during their pregnancy. If not treated, pregnant women with hypothyroidism can develop high blood pressure (preeclampsia) and have a premature delivery. Children born to women with untreated hypothyroidism during pregnancy are at risk for having hypothyroidism at birth and low birth weight and may score lower on intelligence tests than children of healthy mothers.⁷

After delivery, women may develop a thyroid disorder called postpartum thyroiditis. This condition occurs in about 5% of women who do not have a history of thyroid disease.⁷ It is often mistaken for depression.

Women with postpartum thyroiditis often develop hypothyroidism 4 to 8 months after delivery. The hypothyroidism usually lasts 2 to 8 weeks but may last up to 12 weeks.⁵ It sometimes occurs after an initial episode of postpartum thyroiditis that causes symptoms from too much thyroid hormone (hyperthyroidism). Hypothyroidism becomes permanent in about 25% to 50% of women with postpartum thyroiditis.⁵ Even if thyroid gland function returns to normal, postpartum thyroiditis usually comes back during later pregnancies.

Many factors may increase your risk for developing hypothyroidism. These include:

• Age and sex. Older adults are more likely to develop hypothyroidism than younger people, and women are more likely than men to develop thyroid disease.⁸
• Family history. Hypothyroidism tends to run in families.
• Previous thyroid problems. Thyroid disease, an enlarged thyroid (goiter), and surgery or radiation therapy to treat thyroid problems increase the likelihood of developing hypothyroidism in the future.
• Some lifelong conditions. Diabetes, an autoimmune disease that causes patches of light skin (vitiligo), pernicious anemia, and premature gray hair (leukotrichia) are seen more often in people with hypothyroidism.
• Iodine deficiency. This is rare in the United States but common in areas where iodine is not added to salt, food, and water.
• Medicines. Some medicines can interfere with normal thyroid function, particularly lithium carbonate, amiodarone (such as Amiodarone, Cordarone, and Pacerone), and interferon alfa (such as Infergen, Rebetron, and Wellferon).

Up to 20% of women older than 60 have mild (subclinical) hypothyroidism; about 2% to 5% of people with subclinical disease develop hypothyroidism every year.^{3, 8} Many of the same factors that increase your risk for hypothyroidism also increase your risk for mild hypothyroidism.

Call 911 or other emergency services immediately if you or a person you know has hypothyroidism and has signs of myxedema coma, such as:

• Mental deterioration, such as apathy, confusion, and psychosis.
• Extreme weakness and fatigue that progress to loss of consciousness (coma).
• Severe breathing difficulties, slow heart rate (less than 60 beats per minute), or low body temperature [95° (35°) or below].

See your health professional if you have any symptoms that don't go away, including:

• Feeling tired, sluggish, or weak.
• Memory problems, depression, or difficulty concentrating.
• An inability to tolerate cold.
• Dry skin, brittle nails, or a yellowish tint to the skin.
• Constipation.
• Heavy or irregular menstrual periods that may last longer than 5 to 7 days.

If you have one or two of the above symptoms that have not changed or have changed very little over a long period of time, it is less likely that the symptoms are caused by hypothyroidism. Consult your health professional.

Talk to a health professional if you are pregnant and have some of the above symptoms. Also talk to a health professional if you have hypothyroidism and are pregnant or are trying to become pregnant: your dose of thyroid hormone medicine may need to be changed.

Watchful Waiting

Watchful waiting—a period of time during which you and your health professional observe your symptoms or condition without using medical treatment—is not appropriate for hypothyroidism that is causing symptoms. Treatment should begin as soon as the condition is diagnosed.

Watchful waiting may be appropriate for certain adults with mild (subclinical) hypothyroidism whose blood tests show only modest changes. Talk to your health professional about treatment, its cost and possible risks and benefits. Watch for any signs that you may be getting hypothyroidism. Health professionals often want people to have yearly thyroid function blood tests to check to see if thyroid hormone production is normal.

Who To See

Hypothyroidism can be diagnosed by a:

• Family medicine doctor or other primary care doctor.
• Internist.
• Pediatrician.
• Physician assistant.
• Nurse practitioner.

Hypothyroidism also may be diagnosed by a specialist, such as a gastroenterologist, gynecologist, or psychiatrist, depending on the symptoms you have and who you see to evaluate the symptoms.

Complicated or unusual cases of hypothyroidism may require consultation with an endocrinologist.

To prepare for your appointment, see the topic Making the Most of Your Appointment.

A thorough medical history and physical exam are the first steps in diagnosing hypothyroidism or mild (subclinical) hypothyroidism. If the results lead your health professional to suspect you have hypothyroidism or subclinical hypothyroidism, you will have tests to confirm the diagnosis.

Blood tests are always used to confirm a diagnosis of hypothyroidism or mild hypothyroidism. The tests used most often are:

• Thyroid-stimulating hormone (TSH) assay.
• Thyroxine (T4) measurement.

If the above tests are not normal, the antithyroid antibody test may determine whether you have the autoimmune disease Hashimoto's thyroiditis, in which the body's defense system attacks the thyroid gland:

On rare occasions, the following imaging tests may be used to evaluate a thyroid gland that appears to be abnormal during physical examination:

• Thyroid ultrasound
• Thyroid scan and radioactive iodine uptake (RAIU) test

A blood test called the thyrotropin-releasing hormone (TRH) stimulation test is sometimes used to diagnose rare forms of hypothyroidism caused by diseases affecting the hypothalamus or the pituitary gland. A computed tomography (CT) scan or magnetic resonance imaging (MRI) of the hypothalamus or pituitary gland also may be done to look for any changes in these areas of the brain.

Early Detection

Because of the possibility of mental retardation in infants with hypothyroidism, every state in the United States tests newborns for hypothyroidism. If your baby was not born in a hospital, or if you believe your baby may not have been tested, talk to your health professional. Screening tests for hypothyroidism are not always accurate. Watch your child for symptoms of hypothyroidism, even if test results are negative.

Some health professionals now recommend routine testing for people at risk for hypothyroidism, including:

• People age 35 and older. The American Thyroid Association guidelines recommend that screening begin at age 35 and continue every 5 years thereafter.¹
• People with a strong family history of hypothyroidism.
• People with conditions associated with Hashimoto's thyroiditis, including Addison's disease, rheumatoid arthritis, pernicious anemia, and type 1 diabetes.
• Pregnant women. In pregnant women known to have hypothyroidism, tests should be done at regular intervals to determine whether the dosage of thyroid hormone medicine is adequate.
• Women who are having symptoms of hypothyroidism after pregnancy (postpartum hypothyroidism), such as depression, memory and concentration problems, or thyroid enlargement (goiter). Women who have had hypothyroidism during or after pregnancy should be retested if they become pregnant again.

Not all experts agree on whether to recommend widespread screening for hypothyroidism. Some groups say there is not enough evidence of benefit to recommend screening for everyone. But people who are at high risk—women older than 60 and anyone with a family history of thyroid disease or who has other autoimmune diseases—may want to be screened.^{2, 3}

Hypothyroidism can be easily treated using thyroid hormone medicine. The most effective and reliable thyroid replacement hormone is man-made (synthetic). After starting treatment, you will have regular visits with your health professional to make sure you have the right dose of medicine.

In most cases, symptoms of hypothyroidism start to improve within the first week after you start treatment. All symptoms usually disappear within a few months. Infants and children with hypothyroidism should always be treated. Older adults and people who are in poor health may take longer to respond to the medicine.

• If you have had radiation therapy and have hypothyroidism, or if your thyroid gland has been removed, you will most likely need treatment for the rest of your life. If your hypothyroidism is caused by Hashimoto's thyroiditis, you might also need treatment for the rest of your life. Occasionally, thyroid gland function returns on its own in Hashimoto's thyroiditis.
• If a serious illness or infection triggered your hypothyroidism, your thyroid function most likely will return to normal when you recover.
• Some medicines may cause hypothyroidism. Your thyroid function will return to normal when you stop the medicines.
• If you have mild (subclinical) hypothyroidism, you may not need treatment but should be watched for signs of hypothyroidism getting worse. Current research does not provide clear evidence to support treatment, and many health professionals disagree about whether mild hypothyroidism should be treated. When making the decision to treat mild hypothyroidism, you and your health professional will talk about the possible benefits of improved symptoms compared to potential risks and the costs of medicine and monitoring symptoms. The dose of thyroid medicine must be monitored carefully in people with heart disease because too much medicine increases the risk of chest pain (angina) and irregular heartbeats (atrial fibrillation).

Initial treatment

Your health professional will treat your hypothyroidism with the thyroid medicine levothyroxine sodium (for example, Synthroid, Levoxyl, or Levothroid). Take your medicine as directed. Your health professional will want to see you 6 to 8 weeks later to make sure the dose is right for you.

If you take too little medicine, you may have symptoms of hypothyroidism, such as constipation, feeling cold or sluggish, and gaining weight. Too much medicine can cause nervousness, difficulty sleeping, and shaking (tremors). If you have heart disease, too much medicine can cause irregular heartbeats and chest pain. People with heart disease often start on a low dose of levothyroxine, which is increased gradually.

If you have severe hypothyroidism by the time you are diagnosed, you will need immediate treatment. Severe, untreated hypothyroidism can cause myxedema coma, a rare, life-threatening condition.

Treatment for myxedema coma involves care in an intensive care unit (ICU). Thyroid hormone is given intravenously (IV). If you have trouble breathing, a ventilator may be used. You will also be monitored for heart problems, including heart attack, and treated if necessary.

Treatment during pregnancy is especially important because hypothyroidism can harm the developing fetus.

• If you develop hypothyroidism during pregnancy, treatment should be started immediately. If you have hypothyroidism before you become pregnant, your thyroid hormone levels need to be monitored to determine whether the dosage of thyroid medicine is correct. During pregnancy, your dose of medicine may need to be increased by 25% to 50%.⁶
• You also may need treatment if you develop hypothyroidism after pregnancy (postpartum hypothyroidism). You will be retested for hypothyroidism if you become pregnant again. In some cases, hypothyroidism will go away on its own; in other cases, it is permanent and requires lifelong treatment.

Ongoing treatment

You are likely to need treatment for hypothyroidism for the rest of your life. As a result, you need to take your medicine as directed. For some people, hypothyroidism is a progressive disease and the dosage of thyroid medicine may have to be increased gradually as the thyroid continues to slow down.

Most people treated with thyroid hormone develop symptoms again if their medicine is stopped. If this occurs, medicine needs to be restarted.

If a serious illness or infection triggers your hypothyroidism, your thyroid function most likely will return to normal when you recover. To determine whether thyroid function has returned to normal, thyroid hormone medicine may be stopped for a short time. In most people, a brief period of hypothyroidism occurs after thyroid medicine is stopped; there is often a delay in the body's signals that tell the thyroid to start working again. If the thyroid can produce enough hormone on its own, treatment is no longer needed. But if hormone levels remain too low, you need to restart thyroid medicine.

While taking thyroid hormone medicine, you need to see your health professional every 6 to 12 months for checkups. You will have a blood test (thyroid-stimulating hormone (TSH) assay) to make sure you have a normal hormone level.

Treatment if the condition gets worse

Sometimes symptoms of hypothyroidism continue, such as sluggishness, constipation, confusion, and feeling cold. This may occur if you are not taking enough thyroid hormone or if your medicine is not absorbed from your gastrointestinal tract. Having a bowel disease or taking certain other medicines may block thyroid hormone. Your health professional may increase your dose of thyroid medicine if you are taking calcium carbonate, cholestyramine, sucralfate, aluminum hydroxide, ferrous sulfate, or estrogen.⁶ Take calcium supplements at least 4 hours before or after taking thyroid hormone.⁹

If your dose of thyroid hormone is too high, you may develop complications such as irregular heartbeats and, over time, osteoporosis. If you have heart disease, too much medicine can cause pain (angina) and irregular heartbeats. Your health professional will monitor your thyroid levels using a thyroid-stimulating hormone (TSH) assay. If necessary, your health professional will lower your dose.

Most cases of hypothyroidism in the United States are caused by Hashimoto's thyroiditis, which cannot be prevented.

Although you cannot prevent hypothyroidism, you can watch for signs of the disease so it can be treated promptly. Some people who are at high risk of having hypothyroidism but do not have symptoms can be tested to see whether they have mild, or subclinical, hypothyroidism.

Expert groups differ in their recommendations for screening:

• The American Thyroid Association recommends that all adults be tested beginning at age 35 and continuing every 5 years.¹ Older adults, especially women older than 60, those with a family history of hypothyroidism, and those with Addison's disease, rheumatoid arthritis, pernicious anemia, and type 1 diabetes should also be tested, according to these recommendations.
• The U.S. Preventive Services Task Force makes no recommendation for or against thyroid screening for people who do not have symptoms of hypothyroidism. Its statement indicates there is not enough evidence to support screening.²
• Another panel of experts from several medical specialties recommends against widespread screening.³ However, these health professionals say that if you are high risk, you may want to be screened. Those at high risk include women older than age 60 and people who have type 1 diabetes or other autoimmune diseases.³ Talk to your health professional about whether you should be screened.

If you have hypothyroidism, see your health professional every 6 to 12 months so your condition can be closely monitored and your treatment adjusted, if necessary.

It is important to take thyroid hormone medicine correctly. Talk with your health professional if you do not understand the reason for taking medicine regularly or if you think you have any side effects from the medicine. You usually need to have regular blood tests to determine whether you are receiving the correct amount of thyroid hormone.

Children with hypothyroidism also need to see a health professional regularly because the amount of thyroid hormone medicine they need changes as they grow. Untreated hypothyroidism in infants and very young children can have severe consequences. As soon as you think your child is old enough to share the responsibility for his or her own health care (usually around age 9 or 10), teach him or her about hypothyroidism, the importance of taking medicine correctly, and why regular health checkups are important.

Some health food stores in the United States sell “natural” forms of thyroid hormone. The quality and effectiveness of these natural agents are unregulated. Some may not work at all. Others may have an active ingredient that does work but that may be dangerous to certain people.

Thyroid hormone medicine is the only effective way to treat hypothyroidism. In most cases, thyroid hormone medicine:

• Reduces or eliminates symptoms of hypothyroidism. Symptoms usually improve within the first week after you begin therapy. All symptoms usually disappear within a few months.
• May reduce the risk of slowed physical growth, mental retardation, and behavioral problems in infants and children.

Thyroid hormone medicine does not cause side effects if you take the correct dose.

Medication Choices

Thyroid hormone medicine, such as levothyroxine sodium (for example, Synthroid, Levoxyl, or Levothroid)

What To Think About

People with hypothyroidism need treatment with thyroid hormone medicine. Depending on the cause of their hypothyroidism, they may need treatment for the rest of their lives.

Taking certain supplements, such as calcium or iron (or both), at the same time as thyroid hormone medicine may reduce the amount of thyroid hormone medicine absorbed by the body. Take calcium supplements at least 4 hours before or after taking thyroid hormone medicine.⁹ Also avoid taking iron supplements at the same time as thyroid medicine.

Talk to your health professional about whether you need to change your dose of thyroid medicine if you also take birth control pills or other hormones. You may need to take more thyroid hormone medicine than you would if you were not taking these hormones.¹⁰

Follow-up visits with your health professional are important to make sure that you are taking the correct dose of medicine. Most people return to their health professional for blood tests 6 to 8 weeks after starting treatment. After thyroid hormone levels return to normal, thyroid function tests are rechecked every 6 to 12 months.

There is no surgical treatment for hypothyroidism.

There is no other treatment for hypothyroidism at this time.

Organizations

• Hyperthyroidism
• Thyroid Cancer
• Thyroid Nodules

Citations

1. Ladenson PW, et al. (2000). American Thyroid Association guidelines for detection of thyroid dysfunction. Archives of Internal Medicine, 160: 1573–1575.

2. U.S. Preventive Services Task Force (2004). Screening for thyroid disease: Recommendation statement. Annals of Internal Medicine, 140: 125–141.

3. Surks MI, et al. (2004). Subclinical thyroid disease: Scientific review and guidelines for diagnosis and management. JAMA, 291(2): 228–238.

4. LaFranchi S (2004). Hypothyroidism section of Disorders of the thyroid gland. In RE Behrman et al., eds., Nelson Textbook of Pediatrics, 17th ed., pp. 1872–1979. Philadelphia: Saunders.

5. Utiger RD (2001). Hypothyroidism section of The thyroid: Physiology, thyrotoxicosis, hypothyroidism, and the painful thyroid. In P Felig, L Frohman, eds., Endocrinology and Metabolism, 4th ed., pp. 315–329. New York: McGraw-Hill.

6. Larsen PR, Davies TF (2003). Hypothyroidism and thyroiditis. In PR Larsen, ed., Williams Textbook of Endocrinology, 10th ed., pp. 423–455. Philadelphia: Saunders.

7. American College of Obstetricians and Gynecologists (2002). Thyroid disease in pregnancy. ACOG Practice Bulletin No. 37. Obstetrics and Gynecology, 100(2): 387–396.

8. Singer PA (2005). Hypothyroidism. In RE Rakel, ET Bope, eds., Conn's Current Therapy, pp. 760—763. Philadelphia: Elsevier Saunders.

9. Singh N, et al. (2000). Effects of calcium carbonate on the absorption of levothyroxine. JAMA, 283(21): 2822–2825.

10. Roberts CG, Ladenson PW (2004). Hypothyroidism. Lancet, 363: 793–803.

Other Works Consulted

• Abramowicz M, ed. (2006). Drugs for hypothyroidism and hyperthyroidism. Treatment Guidelines from the Medical Letter, 4(44): 17–24.

• Greenspan FS (2004). The thyroid gland. In FS Greenspan, DG Gardner, eds., Basic and Clinical Endocrinology, 7th ed., pp. 215–294. New York: McGraw-Hill.

• Jameson JL, Weetman AP (2005). Disorders of the thyroid gland. In DL Kasper et al., eds., Harrison's Principles of Medicine, 16th ed., vol. 2, pp. 2104–2127. New York: McGraw-Hill.

• Nygaard B (2005). Primary hypothyroidism. Online version of Clinical Evidence (14): 1–6.

Author:	Sabra L. Katz-Wise	Last Updated August 22, 2006
Medical Review:	Kathleen Romito, MD - Family Medicine Hanan Bassyouni, MD - Endocrinology and Metabolism
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