Geriatrics

Geriatrics, specialized branch of medicine that deals with the diseases of older persons and their therapy. The study of the aging process itself is called gerontology. Increased interest in geriatrics is due largely to the greater number of older persons in society, which is in turn a result of social and medical changes that have extended the life expectancy in the United States from an average of 47 years in 1900 to 76.3 years in 2000. The elderly population is expected to increase rapidly over the next 30 years, with the number of persons over 85 growing most rapidly.

In 1975 the U.S. Congress established the National Institute on Aging (NIA) to sponsor research on aging and on therapy for the problems of older persons. In 1978 the Institute of Medicine of the National Academy of Sciences issued a report recommending greater integration of knowledge on aging and geriatrics into the curriculum of medical schools. Some physicians have advocated establishing special geriatric care units in hospitals and outpatient health clinics. Nevertheless, Robert Butler, the first director of the NIA, identified one of the limits to advancing the study of geriatric medicine when he observed that traditional medical education trains physicians to think in terms of cure. This concept is not usually applicable in geriatrics, as many medical conditions of elderly persons can only be ameliorated, not cured.

One problem of the elderly is intellectual impairment. A 1980 task force of the NIA stated that 10 percent of persons over the age of 65 years have some serious mental impairment. They disputed, however, the notion of the inevitability of the process and stated that normal aging does not include gross intellectual impairment, confusion, depression, hallucinations, or delusions. The task force estimated that intellectual impairment can be reversed in close to 20 percent of these cases. Treatable causes of mental deterioration include alterations in functioning of the thyroid gland, sleep disorders, depression resulting from bereavement, infectious and metabolic diseases, and the side effects of therapeutic drugs. This last cause is especially important, because the average person over the age of 65 takes 13 different medicines in a year. Because some of these drugs may interact and cause toxic effects, and because the human metabolism clears drugs from the body less rapidly as people get older, an increased probability exists of interference with mental function. The NIA task force stressed that physicians treating older persons must be alert to these effects.

Mental changes in the elderly may also be due to irreversible conditions, such as the degenerative brain disease called Alzheimer's disease. No cure exists and the course of the illness is variable, usually leading to death within five to ten years. Mental impairment can also result from multiple small strokes.

Older persons are also more susceptible to diseases found in people of all ages, as witnessed by their increased risk of death from influenza infection or exposure to cold. Heat, too, is more dangerous to the elderly. In the heat wave of 1980 the mortality rate among persons over the age of 65 was found to be more than ten times greater than that among other age groups.

In addition, progressive diseases tend to become more severe in old age. These include heart disease (see Heart; arthritis; diabetes mellitus; glaucoma), and cataracts. The weakening of the immune system may lead to an increased incidence of cancer in older persons.

See also Aging.

Pulmonary Diseases

Pulmonary Diseases, diseases affecting the lungs. Though the mouth, nose, and throat help filter and clean the air we breathe, the lungs are subject to inhaled pathogens, such as bacteria and viruses, as well as such toxic substances as cigarette smoke or air pollution.

For information on:

• bacterial and viral diseases affecting the lungs, see Influenza; Legionnaires' Disease; Pneumonia; Tuberculosis
• lung problems caused by environmental factors, see Altitude Sickness; Bronchitis; Emphysema
• pulmonary problems due to allergy or other causes, see Bronchial Asthma; Croup
• congenital pulmonary diseases, see Cystic Fibrosis; Heart: Congenital Diseases
• areas where climate is beneficial to sufferers, see Adirondack Mountains

Hematology

Hematology, medical specialty concerned with the study of blood and blood-forming tissues. Physicians in this field are known as hematologists. They study, diagnose, and treat blood disorders such as leukemia, anemia, and hemophilia, as well as diseases of the organs that produce blood, including the lymph nodes, bone marrow, and spleen.

Hematologists use laboratory-based blood tests to diagnose a variety of disorders. Of particular importance are blood tests that provide information about the cellular components of a patient's blood. The most common test, called a complete blood count (CBC), indicates the number of red blood cells, white blood cells, and platelets in a given unit of blood. Hematologists also examine blood samples under a microscope to identify abnormal blood cells and diagnose blood diseases. In addition to testing for blood diseases, hematologists may also be called on to diagnose other types of disorders, such as hepatitis C, a chronic liver disease that is detected in the blood.

Hematologists treat chronic blood disorders such as leukemia, a broad group of cancerous diseases of blood-forming organs. The condition affects white blood cells and is usually diagnosed by blood tests that indicate abnormal numbers of these cells. Treatment, which often is coordinated by hematologists and cancer specialists called oncologists, typically involves a combination of drug and radiation therapy and may also include a bone marrow transplant (see Medical Transplantation).

Another blood disorder commonly treated by hematologists is anemia, a deficiency of hemoglobin, the component of red blood cells responsible for transporting oxygen. The disorder, which reduces the oxygen-carrying capability of blood, is often caused by the inability of the bone marrow to produce enough new red blood cells. Hematologists detect anemia with a blood test and treat the various types of the disease with such methods as vitamin and mineral supplements, hormone therapy, and blood transfusions.

Hemophilia, a genetic blood disorder studied and treated by hematologists, impairs blood clotting. The disease is detected by a blood test; more recently, genetic tests have been used to diagnose hemophilia as well as to determine a parent’s risk of passing the disorder to the next generation. People with hemophilia usually receive transfusions of plasma, the fluid component of blood, containing concentrated doses of a protein that aids clotting.

In recent years hematologists have undertaken serious efforts to improve the safety of the blood supply. In the past, blood transfusions were implicated in the spread of infectious diseases transmitted by contaminated blood. With biochemists, hematologists developed screening tests to detect the presence of many infectious diseases, including several forms of viral hepatitis and acquired immunodeficiency syndrome (AIDS). Donated blood is now screened for infectious diseases to ensure its safety before it is used in transfusions.

Those seeking a career in hematology must obtain a medical degree and complete a three-year in-hospital training program called a residency, followed by one or two years of additional clinical training in hematology.

Gastroenterology

Gastroenterology, medical specialty that focuses on the human digestive system and the diseases that affect it. Specialists in the field, called gastroenterologists, study and treat disorders of the esophagus, stomach, small and large intestines, and colon—collectively called the gastrointestinal tract—as well as disorders of the liver, gallbladder, and other organs involved in digestion.

Among the most common conditions that gastroenterologists care for are disorders of the stomach, the organ that receives, stores, and partially digests food in the early steps of human digestion. Gastritis, for example, is an inflammation of the stomach lining that often results in abdominal pain, nausea, and vomiting. Gastritis may be caused by the bacterium Helicobacter pylori, viral infections, stress, allergies, and reactions to alcohol, aspirin, or other substances. A gastroenterologist must identify the causative agent in order to treat this inflammation.

Gastroenterologists also specialize in treating peptic ulcers, sores or erosions in the lining of the stomach or the first portion of the small intestine, called the duodenum. Superficial ulcers cause indigestion and other pain; ulcers causing deeper erosion may lead to abdominal bleeding and, if untreated, death. In recent years, researchers have found a definitive link between Heliobacter pylori and chronic ulcers. Gastroenterologists prescribe antibiotics that kill this bacterium, as well as medications that buffer the acidity in the stomach or slow the stomach’s secretion of digestive acids.

Gastroenterologists treat many diseases related to other organs involved in digestion. The esophagus, for example, can become inflamed from the presence of gastric acid from the stomach, causing heartburn. This condition, known as acid reflux, may be treated with weight loss, drugs that limit the secretion and acidity of gastric acid, and surgical procedures. In the liver, common disorders include hepatitis, an inflammation caused by infection or toxic agents, and cirrhosis, a condition frequently caused by alcohol damage that can ultimately lead to liver failure. Gastroenterologists also treat gallstones, lumps of solid matter found in the gallbladder; inflammation of the pancreas, called pancreatitis; and inflammation of the colon, called colitis.

Gastroenterologists use a variety of highly specialized tools to examine, diagnose, and treat disorders of the gastrointestinal tract. In a procedure called endoscopy, physicians use a long, flexible tube with magnifying lenses and a light source, called an endoscope, to examine internal body cavities. Endoscopes are fitted with specialized attachments, such as grasping forceps or brushes, that enable the physician to remove small tissue samples for laboratory analysis, in a procedure called a biopsy. Endoscopes are also equipped with lasers that enable gastroenterologists to treat disorders without performing more invasive surgery. For example, gastroenterologists cauterize, or burn, peptic ulcers with laser-equipped endoscopes.

Those seeking a career in gastroenterology must first earn a medical degree, then complete a three-year in-hospital training program called a residency, followed by two years of specialized training in gastroenterology and a certification exam.

Internal Medicine

Internal Medicine, nonsurgical medical specialty concerned with diseases of internal organs in adults. Physicians who specialize in the field, known as internists, are skilled in disease prevention and in managing complex disorders of the body. Internists may be either generalists or specialists.

General internists typically act as personal physicians, developing long-term relationships with patients. Internists give patients regular physical examinations, offer preventive care, diagnose and treat most nonsurgical illnesses, and refer serious or unusual cases to an appropriate specialist. If a patient complains of persistent stomach problems, for example, a general internist might refer the patient to a gastroenterologist, an internist who specializes in disorders of the digestive system.

Within the field of internal medicine, nine subspecialties are recognized: cardiology, the treatment of diseases of the heart and blood vessels; endocrinology, the study of glands and other structures that secrete hormones; gastroenterology, the care of conditions of the digestive tract, liver, and pancreas; hematology, the study of blood and blood-forming tissues; infectious disease, the study of severe or unusual infections; nephrology, the diagnosis and treatment of kidney diseases; oncology, the study and treatment of cancerous tumors; pulmonary disease, concerned with disorders of the lungs and other components of the respiratory system; and rheumatology, the treatment of disorders involving joints and other connective tissues. An additional subspecialty gaining prominence is geriatrics, the study of diseases affecting older adults.

The development and widespread use of many technologies have enabled internists to perform procedures that formerly were considered the responsibility of surgeons. For example, a procedure called endoscopy, performed using an illuminated tubular instrument called an endoscope, permits doctors to examine and photograph internal organs and manipulate tools inside the body without invasive surgery. Another tool, a narrow tubular device called a cardiac catheter, permits physicians to inject drugs or fluids directly into the heart.

The origins of internal medicine date back to the late 19th century, when the practices of general medicine and surgery began to split into separate disciplines. Over time, internists became hospital-based generalists who played a role somewhere between those played today by family physicians and surgical specialists. Since the mid-1900s internal medicine in the United States has shifted from a primarily generalist field to a discipline in which roughly 65 percent of all internists are certified as subspecialists.

Those seeking a career in internal medicine must obtain a medical degree and complete a three-year in-hospital internal medicine training program. Internists interested in a subspecialty must spend one or two additional years studying that discipline and must pass a certification test. The specialty board for internal medicine, the American Board of Internal Medicine, was established in 1936.