What
Is Hypothyroidism?
The thyroid is a small, butterfly-shaped gland located in the front of the neck, which produces hormones that increase oxygen use in cells and stimulate vital processes in every part of the body. These thyroid hormones have a major impact on growth, use of energy, heat production, and infertility. They affect the use of vitamins, proteins, carbohydrates, fats, electrolytes, and water, and regulate the immune response in the intestine. They can also alter the actions of other hormones and drugs.
The two key thyroid hormones are thyroxine (T4) and L-triiodothyronine (T3). Iodine is the raw material used in the manufacture of these hormones; it is extracted from the blood and trapped by the thyroid gland where 80% of the body's iodine is stored. The thyroid mostly produces thyroxine, which in turn, is converted into T3, the more biologically active thyroid hormone. Only about 20% of T3 is actually formed in the thyroid gland, however; the rest is manufactured from circulating thyroxine in tissues outside the thyroid. The whole process of iodine trapping and thyroid hormone production is directly influenced by another important hormone, thyroid-stimulating hormone (TSH or thyrotropin). This hormone is secreted by the pituitary gland and monitored by thyrotropin-releasing hormone (TRH), which is produced in the hypothalamus gland. Both glands are located in the brain. Any abnormality in this intricate system of glands and hormone synthesis and production can have far-reaching consequences.
When there is inadequate secretion of thyroid hormones, hypothyroidism occurs and the body begins to slow down. It was first diagnosed in the late nineteenth century when physicians observed that after surgically removing the thyroid gland, a patient developed swelling of the hands, face, feet, and tissues around the eye. They named this syndrome myxedema and correctly concluded that it was the outcome of the absence of substances -- thyroid hormones -- normally produced by the thyroid gland, i.e., hypothyroidism. A number of conditions can cause this disorder, and it is usually progressive and irreversible. Treatment for hypothyroidism, however, is nearly always completely successful and allows a patient to live a fully normal life.
What Causes Hypothyroidism?
A number of both permanent and temporary conditions can reduce thyroid hormone secretion and cause hypothyroidism. The most common of these are Hashimoto's thyroiditis, an autoimmune condition, and overtreatment of hyperthyroidism. Hypothyroidism almost always occurs from problems that originate in the thyroid gland, but it can also be caused by disorders of the pituitary or hypothalamus glands. Too much or too little iodide can also cause hypothyroidism. If there is a deficiency of iodide, then the body cannot manufacture thyroxine. Too much iodide is a signal to inhibit the conversion process of thyroxine to T3. The end result in both cases is inadequate production of thyroid hormones.
Autoimmune Thyroiditis
In autoimmune disease, the body's immune system attacks its own cells; in the case of autoimmune thyroiditis, the cells under attack are in the thyroid gland. Experts do not know why the immune system starts to injure the thyroid. One theory is that a virus or bacteria with a protein resembling a thyroid protein might trigger the response. This theory is backed up to some extent by the presence of recent infections in people with autoimmune disease. There is an association between hepatitis C, for instance, and the onset of autoimmune hypothyroidism. Some experts believe the infectious-disease theory is not convincing. An alternative hypothesis is that such patients have abnormal thyroid cells -- possibly from a genetic defect -- that provoke a suicidal process leading to a direct attack by T-cells, important agents in the immune-system. The autoimmune diseases of the thyroid may be categorized as Hashimoto's thyroiditis, atrophic thyroiditis, and postpartum thyroiditis. In a rare autoimmune disorder known as Riedel's thyroiditis, patients develop a hard stony mass that suggests cancer, but the disorder responds well to thyroid replacement and steroids.
Hashimoto's Thyroiditis
The most common form of hypothyroidism is Hashimoto's thyroiditis, a genetic disease named after the Japanese physician who first described thyroid inflammation in 1912. An enlargement of the thyroid gland called a goiter is always present; it may appear as a cyst-like or fibrous growth in the neck. Hashimoto's thyroiditis is permanent and requires life-long treatment.
Atrophic Thyroiditis
Atrophic thyroiditis is similar to Hashimoto's thyroiditis, except a goiter is not present.
Pregnancy-Induced Hypothyroidism
Hypothyroidism develops during or after pregnancy in up to one out of 2,000 women. Some cases are due to thyroid surgery or radiation treatments. Often, however, hypothyroidism occurs because women develop antibodies to their own thyroid during pregnancy, causing an inflammation of the thyroid after delivery. Postpartum autoimmune thyroiditis, which causes hypothyroidism, occurs in about 5% of women and tends to develop between four and 12 months after delivery; it almost always resolves on its own. It may be interrupted by bouts of hyperthyroidism as well. Occasionally, postpartum hypothyroidism can be permanent, particularly in women who have recurrent episodes after multiple pregnancies and in women who have other autoimmune disorders.
Excess Iodine and Deficiencies
Because iodine is the raw material of thyroid hormone, diets deficient in iodine can lead to hypothyroidism. About 200 million people around the world have goiters because of insufficient iodine in their diets, although the condition is almost unheard of in developed nations, where iodine has been added to salt. Excess iodine intake tends to suppress the production of thyroid hormones in anyone. In people with antibodies to their own thyroid but no symptoms of autoimmune thyroiditis, an increase in iodine can bring on symptoms. Countries with the highest intake of iodine, including the US and Japan, however, also have the highest prevalence of chronic autoimmune thyroiditis, and when people in countries deficient in iodine are given iodine supplements, the rate of this disorder increases.
Treatment of Hyperthyroidism
Graves disease is the most common form of hyperthyroidism, a condition caused by excessive secretion of thyroid hormones. Up to half of patient who receive radioactive iodide -- the standard treatment for Graves disease -- develop permanent hypothyroidism within a year of therapy. By the end of five years, about 65% of patients have developed hypothyroidism, after which the rate of hypothyroidism levels off to about 1% a year. Such patients need to take thyroid hormones for the rest of their lives. Other forms of treatment for overactive thyroid glands using either antithyroid drugs or surgery may also result in hypothyroidism (see Thyroid Surgery, below).
Thyroid Surgery
Complete removal (total thyroidectomy) of the thyroid to treat thyroid cancer requires a lifetime of treatment with an appropriate dosage of thyroid hormone. Removal of one of the two lobes of the thyroid gland (hemithyroidectomy) because of benign growths on the thyroid gland rarely produces hypothyroidism. The remaining thyroid lobe will generally enlarge so that it can produce sufficient amounts of thyroid hormone for normal function. Many physicians recommend thyroid hormone treatment, however, to prevent the formation of additional nodules. The small percentage of Graves' disease patients who require surgery to remove most of both thyroid lobes (subtotal thyroidectomy) may develop hypothyroidism. It is important to find an experienced surgeon for this procedure and to have the thyroid checked at six- or 12-month intervals.
Causes of Hypothyroidism in Infants
A number of unusual conditions can induce hypothyroidism in newborns -- known as congenital hypothyroidism, which occurs in about .04% of infants. Up to 90% of these cases are caused by abnormal development of the thyroid gland while in the womb. Other causes include genetic problems in hormone production, iodine deficiency, and ingestion of antithyroid drugs by the pregnant mother. Congenital hypothyroidism is usually permanent. Pregnant women with antibodies that inhibit thyroid hormone production may pass these antibodies on to their infants, who will then require long-term treatment for hypothyroidism starting at birth. Finally, temporary hypothyroidism can occur in premature infants because the central nervous system connections between the hypothalamus and pituitary glands have not yet matured; this condition generally resolves between four to 16 weeks after birth.
Drugs
Lithium, a drug widely used to treat psychiatric disorders, has multiple effects on thyroid hormone synthesis and secretion. Up to 50% of patients who take lithium develop goiter, with 20% developing symptomatic hypothyroidism and another 20% to 30% developing hypothyroidism without symptoms. The drug amiodarone (Cordarone), which is used to treat abnormal heart rhythms contains iodine and can induce hypothyroidism, particularly in patients with an existing thyroid problem. Certain antidepressants may cause hypothyroidism, although this effect is infrequent. Drugs used for epilepsy, including phenytoin and carbamazepine, reduce thyroid levels. Many other drugs contain iodine or have properties that effect the thyroid, although their effects are almost always reversible when they are stopped. Large doses of selenium, a common over-the-counter supplement, may also lower thyroid levels.
Radioactive Iodine
High-dose radiation for cancers of the head or neck and for Hodgkin's disease can also cause hypothyroidism in up to 65% of patients within 10 years after treatment.
Secondary Hypothyroidism
In rare instances, usually due to a tumor, the pituitary gland will fail to produce thyrotropin (TSH), the hormone that stimulates the thyroid to produce its hormones. In such cases, the thyroid gland withers. When this happens, secondary hypothyroidism occurs.
What Are the Symptoms of Hypothyroidism?
Subclinical Hypothyroidism
Symptoms in adults, particularly those over 50, usually begin so gradually that hypothyroidism is often first diagnosed on blood tests, a condition called subclinical hypothyroidism. This condition occurs in up to 15% of people -- mostly women -- over 60.
Symptomatic Hypothyroidism
Subclinical hypothyroidism progresses to overt hypothyroidism in about 2% of untreated people per year. The symptoms increase as the disease progresses and the metabolism slows down.
Early Symptoms
Many people attribute the early symptoms of hypothyroidism to stress or aging. They begin to feel chronically tired and overly sensitive to cold. Muscle and joint aches often develop. Weight gain is common even though appetite diminishes. Constipation can be a problem, and premenopausal women may experience heavy periods or, in rare cases, a milky discharge from the breasts. As free thyroxine levels fall over the following months, the skin becomes rough and dry, hair coarsens, and mental activity, including concentration and memory, may become slightly impaired. Depression develops. Some experts believe that even mild thyroid failure may increase susceptibility to major depression
Later Symptoms
If untreated, the classic physical changes characteristic of myxedema can develop -- a round puffy face with a sleepy appearance, dry rough skin, and loss of hair. Other later symptoms include a husky voice and numbness of the arms and legs. Muscle pain and weakness may occur, in some cases causing carpal tunnel syndrome. Some people experience hearing loss. Depression, mental confusion, unsteadiness, daytime sleepiness, and memory problems may occur, especially in the elderly. Obstructive sleep apnea is common, in which tissues in the upper throat collapse at intervals during sleep, thereby blocking the passage of air.
Symptoms of Secondary Hypothyroidism
In secondary hypothyroidism, which is caused by pituitary growth, in addition to the usual symptoms of primary hypothyroidism, sexual drive and fertility may be impaired in both men and women. Decreased adrenal gland function may lead to an array of symptoms, including exhaustion, low blood pressure, and salt craving. Headaches and visual disturbances may develop, which are directly related to the pituitary tumor.
Symptoms in Infants and Children
All babies are now screened for hypothyroidism in order to prevent retardation that can occur if the disorder is not detected early. Most children who are born with a defect that causes congenital hypothyroidism have no obvious symptoms. Others may be born late (two to three weeks after term), have jaundice, noisy breathing, and enlarged tongues. Some early symptoms that develop in children who are not treated include feeding problems, failure to thrive, constipation, hoarseness, and sleepiness. Later on, they may have protruding abdomens, rough dry skin, and delayed teething. If they do not receive proper treatment in time, they may be extremely short for their age, have a puffy, bloated appearance, and have below-normal intelligence. A child who grows abnormally slowly should be examined for hypothyroidism.
What Other Diseases Show the Same Symptoms as Hypothyroidism?
Aging-Related Disorders
Some symptoms of hypothyroidism and aging are very similar. Many of the problems of aging, such as vitamin deficiencies, Parkinson's and Alzheimer's diseases, and arthritis have characteristics that can mimic hypothyroidism.
Obesity
Many people who are overweight believe that they have an underactive thyroid gland, but only a small percentage of obese people actually have hypothyroidism. Hypothyroid patients generally show a moderate weight increase of five to 10 pounds, mainly from accumulation of fluid.
Depression
A lack of interest in personal relationships, drowsiness, an increase in sleep, slowing of speech, and general apathy are signs of clinical depression as well as hypothyroidism. Although patients who have clinical depression do not usually have hypothyroidism, hypothyroidism should be considered as a possible cause of chronic depression, particularly in older women. Some psychiatrists suspect that even subclinical hypothyroidism may contribute to depression. Adding thyroid hormones to antidepressants, in fact, hastens a depressed patient's recovery. A recent study indicated that the two may have some common physiological basis. In the study, both L-triiodothyronine (T3) and L-tryptophan (a chemical important for feelings of well-being) appeared to be taken up by red blood cells using the same carrier. Interesting implications of the study are that alterations in one substance may affect that other.
Diseases of Muscles and Joints
Joint and muscle pain may be the first symptoms of hypothyroidism. Most likely, however, such pain is not caused by hypothyroidism if other thyroid symptoms remain absent. Numerous conditions can cause muscle and joint pain, and if thyroid levels are normal the physician should look for other causes.
Who Gets Hypothyroidism?
Age and Gender
Experts estimate that as many as 13 million Americans have a thyroid disorder, but up to eight million may go undiagnosed, since many people do not know that they have a thyroid deficiency. Mild thyroid failure occurs in 4% to 17% of women and 2% to 7% of men, with the risk increasing with age. The elderly are most susceptible, but hypothyroidism can affect people of all ages. For example, one out of every 4,000 infants is born with congenital hypothyroidism; female infants are at higher risk than males. Hashimoto's thyroiditis affects about 5% of adults, and women are three to eight times more likely than men to develop the disorder. Some experts estimate that as many as 10% of women over 50 have some indication of this condition.
Genetic Defects
Heredity plays a role in both underactive and overactive thyroid. About half of those with close relatives with chronic autoimmune disease have antibodies to the thyroid. (Antibodies are the immune system's agents for attacking specific proteins.) Thyroid disease will often skip generations; someone with an underactive thyroid may have healthy parents but have grandparents who had thyroid troubles. Some people inherit a tendency to thyroid problems but never become ill, while others become very sick. As many as half of those with Turner's syndrome, one of the most common genetic diseases in women, have hypothyroidism, usually from Hashimoto's thyroiditis.
Smoking
Pregnant women with subclinical hypothyroidism who smoke between one and two packs of cigarettes daily are at risk for even lower thyroid function as well as decreased action of TSH in areas outside the thyroid, such as the liver. These women may also develop significantly higher levels of total cholesterol and LDL, the so-called bad, cholesterol than non-smoking women with subclinical hypothyroidism.
Risk Factors for Pregnant Women
Women who have diabetes or other autoimmune conditions have a 25% risk for hypothyroidism during gestation. Having a miscarriage, in some cases, may be indicate the presence of antithyroid antibodies during early pregnancy; autoimmune thyroiditis can develop during the subsequent year.
Other Risk Factors
Hypothyroidism occasionally occurs with Addison's disease, pernicious anemia, and myasthenia gravis. It is also associated with ovarian failure, sleep apnea, premature gray hair, left-handedness, insulin-dependent diabetes, and rheumatoid arthritis. Physicians should check for hypothyroidism in older people with any of these conditions. People with anorexia or bulimia are at risk for hypothyroidism; in these cases, however, reduced thyroid function may be an adaptation to malnutrition and therefore some experts think only the eating disorder should be treated, not hypothyroidism. So many drugs affect the thyroid, that anyone being treated for a chronic disease, who is taking thyroid medication and requires other drugs, or who is at risk for thyroid disorder and needs to take medications should discuss the impact of the drug on their thyroid.
How Serious Is Hypothyroidism?
Although hypothyroidism carries serious risks for all ages, it is now easily diagnosed, and treatment with thyroid hormones will restore normal thyroid function and relieve symptoms and physical signs of the disease. With such treatment, a patient should expect to live a normal life, free of harmful consequences. It should be noted, however, iodine deficiency and goiter are still major problems in less developed nations, causing varying degrees of mental retardation in 20 million people.
Effects on Health
Hypothyroidism is associated with atherosclerosis (commonly known as hardening of the arteries) and heart disease. Most likely this higher risk is because high levels of low-density lipoprotein (LDL) cholesterol (the "bad" cholesterol) often occur in people with hypothyroidism. LDL levels may be high even in subclinical hypothyroidism. Another elevated risk factor for heart disease in those with hypothyroidism is a cholesterol-carrying molecule called lipoprotein(a), or lp(a). Treatment of hypothyroidism can significantly reduce total cholesterol, LDL, and lp(a), helping to prevent the development of atherosclerosis.
Hypothyroidism may also slow the heart rate to less than 60 beats per minute and reduce the hearts' pumping capacity. For this reason there has been some concern about an increased risk for high blood pressure. A recent study has found no such association, at least in older women. Hypothyroidism does increase the risk for high blood pressure in pregnant women however. In any case, all patients with chronic hypothyroidism should have their blood pressures checked regularly.
Hypothyroidism is also commonly associated with iron deficiency anemia and respiratory problems. Some research has associated hypothyroidism with an increased risk for glaucoma.
Myxedema Coma
If hypothyroidism is not treated, or if drugs, infections, stress, or other traumatic situations worsen existing hypothyroidism, an emergency condition can develop with severe manifestation of myxedema. The patient can experience a severe drop in body temperature (hypothermia), seizures, stupor, and finally coma.
Effects on the Mind
Depression is common even in early stages and can become severe. Untreated hypothyroidism can, over time, cause mental and behavioral impairment, and eventually may even cause dementia. Whether treatment can completely reverse problems in memory and concentration is uncertain, although many experts believe that only mental impairment in hypothyroid that occurs at birth is permanent.
Risks for Infants and Children
Infants born with congenital hypothyroidism need to receive treatment as soon as possible after birth to prevent mental retardation, stunted growth, and other aspects of abnormal development -- a condition known as cretinism. It has been estimated that untreated infants lose three to five IQ points per month during the first year. An early start of life-long treatment avoids or minimizes this damage. Transient hypothyroidism is common among premature infants; severe cases can cause difficulties in neurologic and mental development.
If hypothyroidism develops in children after two years, mental retardation is not a danger, but physical growth may be slowed and new teeth delayed. If treatment is given late, adult growth could be affected. Even with treatment, some children with severe hypothyroidism may have attention problems and hyperactivity.
Infertility and Pregnancy
Most women with hypothyroidism fail to produce eggs, and they may receive a diagnosis of hypothyroidism for the first time during a fertility evaluation. A pregnant woman with hypothyroidism is at higher risk for miscarriage. Those who remain hypothyroid near the time of delivery are in danger of developing high blood pressure and premature delivery. They are also prone to postpartum thyroiditis, which is said to be a contributor to postpartum depression. Children born to untreated women are at risk for mental defects.
Childhood X-Ray Treatments
Two million Americans, mostly children, received x-ray treatments to the head or neck between 1920 and 1960 for acne, enlarged thymus gland, recurrent tonsillitis, or chronic ear infections. The risk of developing thyroid nodules and thyroid cancers is increased in these individuals. Cancer can develop as long as 40 years after the original treatment and is a particular risk in those who develop hypothyroidism. Everyone who has had head and neck radiation should be sure to have their thyroid glands examined regularly.
Well-Connected Board of Editors
Harvey Simon, M.D., Editor-in-Chief
Massachusetts Institute of Technology; Physician, Massachusetts General
Hospital
Masha J. Etkin, M.D., Gynecology
Harvard Medical School; Physician, Massachusetts General Hospital
John E. Godine, M.D., Ph.D., Metabolism
Harvard Medical School; Associate Physician, Massachusetts General
Hospital
Daniel Heller, M.D., Pediatrics
Harvard Medical School; Associate Pediatrician, Massachusetts General
Hospital; Active Staff, Children's Hospital
Irene Kuter, M.D., D. Phil., Oncology
Harvard Medical School; Assistant Physician, Massachusetts General
Hospital
Paul C. Shellito, M.D., Surgery
Harvard Medical School; Associate Visiting Surgeon, Massachusetts General
Hospital
Theodore A. Stern, M.D., Psychiatry
Harvard Medical School; Psychiatrist and Chief, Psychiatric Consultation
Service, Massachusetts General Hospital
Carol Peckham, Editorial Director
Cynthia Chevins, Publisher
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What
Tests Will Confirm the Diagnosis of Hypothyroidism? Advances in diagnostic methods now make it possible to detect hypothyroidism in almost all cases before severe symptoms develop. Physicians can make the diagnosis of hypothyroidism after completing a history and physical exam of the patient and performing sensitive laboratory tests on the patient's blood. Some physicians believe that because thyroid problems are so common in the elderly and thyroid hormone tests are so inexpensive, blood tests for thyroid function should be routine. One study reported that in elderly patients who require emergency surgery and have undiagnosed hypothyroidism, the consequences can be very serious, even fatal. The American College of Physicians now recommends that women over 50 years old should be screened every five years. Researchers in one study, in fact, reported that screening men and women at age 35 and every five years afterward would be cost-effective and would prevent progression to hypothyroidism in people with mild thyroid failure but no symptoms (subclinical hypothyroidism). It might also help prevent unhealthy cholesterol levels in such people. Other experts feel, however, that cholesterol levels can be lowered through other means and that there is no evidence that treating people who have only mildly abnormal thyroid levels and no symptoms would improve their lives. Physical Examination A goiter (an enlarged thyroid) may be evident on examination. A rubbery, painless goiter may be an indication of Hashimoto's disease. If the thyroid is tender and enlarged but not necessarily symmetrical, the physician may suspect subacute thyroiditis. A diffusely enlarged gland may occur in hereditary hypothyroidism, in postpartum patients, or from use of iodides or lithium. The physician will check the heart, eyes, hair, skin, and reflexes. Measuring Thyroid Hormone
Levels Thyroid-stimulating hormone (TSH) and thyroxine (T4) levels are usually both measured using blood samples, although TSH is the more sensitive indicator of hypothyroidism. Its function is to stimulate thyroxine production when levels drop, and so the pituitary gland secretes more TSH as soon as it senses even slight reductions in thyroxine levels. In fact, thyroxine may still be within normal range when the pituitary begins to increase the supply of TSH. If TSH levels are elevated above 6 mU/L regardless of thyroxine levels -- the physician can still make a diagnosis of hypothyroidism, although the condition is considered to be subclinical if thyroxine levels are normal and the patient has no symptoms. In the very elderly or seriously ill patients and during pregnancy both thyroxine and TSH levels may be extremely variable; in such patients measurements of the hormones should be repeated before starting thyroid-hormone therapy. Tests called sensitive thyroid-stimulating hormone (sTSH) assays and so-called free thyroxine (fT4) assays have been developed and are believed to be very accurate; one study reported that sTSH was so accurate that the fT4 test was not needed. Childhood Screening Almost all newborns with hypothyroidism are identified shortly after birth through an effective national screening program using a thyroid blood test. Each year over 1,500 children are now saved from subnormal intelligence. Testing during Pregnancy Because untreated hypothyroidism is a serious problem for the unborn child, all pregnant women should be tested for thyroid function. Elevated levels of estrogen during pregnancy cause thyroid hormone levels to rise. Therefore, a pregnant women with an underactive thyroid may have what appears to be normal levels of thyroid hormones, but she may actually be hypothyroid. A blood test showing elevated TSH levels, however, is a reliable indicator of an underactive thyroid, even in pregnancy. Antithyroid Antibodies A blood test for antithyroid antibodies is sometimes used to detect Hashimoto's thyroiditis, particularly in patients who have knobby goiters. If high levels of antibodies are present Hashimoto's thyroiditis is a certain diagnosis. Even if patients have no symptoms at the time of the test, a positive result usually means that a patient has a 4% to 8% chance of developing symptoms each year. Imaging Tests Imaging procedures including x-rays and ultrasound may be used to visualize the thyroid, but they do not measure the thyroid gland's function. Thyroid scans are then used to determine whether the thyroid is producing normal amounts of hormone. The patient drinks a small amount of radioactive iodine or technetium and waits until it has been through the thyroid. Images of a properly functioning thyroid would show uniform levels of absorption throughout the gland. Overactive areas would show up white and underactive areas would appear dark. Thyroid scans are usually unnecessary unless the physician needs to rule out suspected cancer. If laboratory tests suggest that a pituitary or hypothalamus problem is causing hypothyroidism, the physician will usually order brain imaging procedures using computed tomography (CT) scans or magnetic resonance imaging (MRI). Needle Aspiration Biopsy Needle aspiration biopsy is a common procedure performed in a doctor's office and used to obtain thyroid cells for microscopic evaluation. Much like drawing blood, the physician injects a small needle into the thyroid gland and draws cells from the gland into a syringe. The cells are put onto a slide, stained, and examined under a microscope. Other Blood Tests Other blood tests may be performed to detect levels of calcitonin, calcium, prolactin, thyroglobulin and to check for anemia and liver function, all of which may be affected by hypothyroidism. Well-Connected Board of Editors Harvey Simon, M.D., Editor-in-Chief Masha J. Etkin, M.D., Gynecology John E. Godine, M.D., Ph.D., Metabolism Daniel Heller, M.D., Pediatrics Irene Kuter, M.D., D. Phil., Oncology Paul C. Shellito, M.D., Surgery Theodore A. Stern, M.D., Psychiatry Carol Peckham, Editorial Director Cynthia Chevins, Publisher |
