Intestinal obstruction is the partial or complete mechanical or nonmechanical blockage of the small or large intestine. There are two types of intestinal obstructions—mechanical and nonmechanical. Mechanical obstructions occur because the bowel is physically blocked and its contents cannot get past the obstruction. Mechanical obstructions can occur for several reasons. Sometimes the bowel t…
The word polyp refers to any overgrowth of tissue from the surface of mucous membranes. Intestinal polyps grow out of the lining of the small and large bowels. Polyps come in a variety of shapes—round, droplet, and irregular being the most common. Polyps are one of many forms of tissue overproduction that can occur in the body. Cells in many body tissues sometimes keep growing beyond their …
Intrauterine growth retardation (IUGR) occurs when the unborn baby is at or below the 10th weight percentile for his or her age (in weeks). There are standards or averages in weight for unborn babies according their age in weeks. When the baby's weight is at or below the tenth percentile for his or her age, it is called intrauterine growth retardation or fetal growth restriction. These babi…
Sterile water solutions containing small amounts of salt or sugar, are injected into the body through a tube attached to a needle that is inserted into a vein. Fever, vomiting, and diarrhea can cause a person to become dehydrated fairly quickly. Infants and children are especially vulnerable to dehydration. Patients can become dehydrated due to an illness, surgery, or accident. Athletes who have o…
Intravenous urography is a test that x rays the urinary system using intravenous dye for diagnostic purposes. Of the many ways to obtain images of the urinary system, the intravenous injection of a contrast agent has been traditionally considered the best. The kidneys excrete the dye into the urine. X rays can then create pictures of every structure through which the urine passes. The procedure ha…
Intussusception is the enfolding of one segment of the intestine within another. It is characterized by and initially presents with recurring attacks of cramping abdominal pain that gradually become more painful. Intussusception occurs when part of the bowel or intestine is wrapped around itself, producing a mass-like object on the right side of the abdomen during palpation (a procedure used durin…
Ipecac is a medicine commonly used to induce vomiting in cases of accidental poisoning. It is also a homeopathic remedy. Standard medical practice uses ipecac to cause vomiting in cases of poisoning in order to remove the toxic substance from the stomach before absorption occurs. It can be used on animals as well as humans. Ipecac is safer and more effective than many other methods for inducing vo…
Anemia can be caused by iron deficiency, folate deficiency, vitamin B12 deficiency, and other causes. The term iron deficiency anemia means anemia that is due to iron deficiency. Iron deficiency anemia is characterized by the production of small red blood cells. When examined under a microscope, the red blood cells also appear pale or light-colored. For this reason, the anemia that occurs with iro…
Iron tests are a group of blood tests that are done to evaluate the iron level in blood serum, the body's capacity to absorb iron, and the amount of iron actually stored in the body. Iron is an essential trace element; it is necessary for the formation of red blood cells and certain enzymes. At the other extreme, high levels of iron can be poisonous. There are four different types of tests …
Irritable bowel syndrome (IBS) is a common intestinal condition characterized by abdominal pain and cramps; changes in bowel movements (diarrhea, constipation, or both); gassiness; bloating; nausea; and other symptoms. There is no cure for IBS. Much about the condition remains unknown or poorly understood; however, dietary changes, drugs, and psychological treatment are often able to eliminate or …
Ischemia is an insufficient supply of blood to an organ, usually due to a blocked artery. Myocardial ischemia is an intermediate condition in coronary artery disease during which the heart tissue is slowly or suddenly starved of oxygen and other nutrients. Eventually, the affected heart tissue will die. When blood flow is completely blocked to the heart, ischemia can lead to a heart attack. Ischem…
Isolation refers to the precautions that are taken in the hospital to prevent the spread of an infectious agent from an infected or colonized patient to susceptible persons. Isolation practices are designed to minimize the transmission of infection in the hospital, using current understanding of the way infections can transmit. Isolation should be done in a user-friendly, well-accepted, inexpensiv…
Itching is an intense, distracting irritation or tickling sensation that may be felt all over the skin's surface, or confined to just one area. The medical term for itching is "pruritus." Itching instinctively leads most people to scratch the affected area. Different people can tolerate different amounts of itching, and anyone's threshold of tolerance can be changed due…
Japanese encephalitis is an infection of the brain caused by a virus. The virus is transmitted to humans by mosquitoes. The virus that causes Japanese encephalitis is called an arbovirus, which is an arthropod-borne virus. Mosquitoes are a type of arthropod. Mosquitoes in a number of regions carry this virus and are responsible for passing it along to humans. Many of these areas are in Asia, inclu…
Jaundice is a condition in which a person's skin and the whites of the eyes are discolored yellow due to an increased level of bile pigments in the blood resulting from liver disease. Jaundice is sometimes called icterus, from a Greek word for the condition. In order to understand jaundice, it is useful to know about the role of the liver in producing bile. The most important function of th…
Jaw wiring, also known as maxillomandibular fixation, is a surgical procedure where metal pins and wires are anchored into the jaw bones and surrounding tissues to keep the jaw from moving. Sports injuries, automobile accidents, falls, or fist-fights are a few of the situations where the jaw might be fractured or broken. In these cases, jaw wiring may be necessary to keep the bones aligned and sta…
Jet lag is a condition marked by fatigue, insomnia, and irritability that is caused by air travel through changing time zones. Living organisms are accustomed to periods of night and day alternating at set intervals. Most of the human body's regulating hormones follow this cycle, known as circadian rhythm. The word circadian comes from the Latin, circa, meaning about, and dies, meaning day.…
A joint or synovial membrane biopsy refers to a procedure where a sample of the joint lining or synovial membrane is taken. A joint biopsy is performed to determine why a joint is painful or swollen. It is usually reserved for more difficult cases where the diagnosis is not clear. The test can be used to diagnose bacterial or fungal infections, an abnormal buildup of iron, cancer, or other disease…
Joint fluid analysis, also called synovial fluid analysis, or arthrocentesis, is a procedure used to assess joint-related abnormalities, such as in the knee or elbow. The purpose of a joint fluid analysis is to identify the cause of swelling in the joints, to relieve pain and distention from fluid accumulation in the joint, and to diagnose certain types of arthritis and inflammatory joint diseases…
Joint replacement is the surgical replacement of a joint with an artificial prosthesis. Great advances have been made in joint replacement since the first hip replacement was performed in the United States in 1969. Improvements have been made in the endurance and compatibility of materials used and the surgical techniques to install artificial joints. Custom joints can be made using a mold of the …
Juvenile arthritis (JA) refers to a number of different conditions, all of which strike children, and all of which have joint inflammation as their major manifestation. The skeletal system of the body is made up of different types of the strong, fibrous tissue known as connective tissue. Bone, cartilage, ligaments, and tendons are all forms of connective tissue that have different compositions, an…
Kaposi's sarcoma is a form of skin cancer that can involve internal organs. It is most often found in patients with acquired immunodeficiency syndrome (AIDS), and can be fatal. Kaposi's sarcoma (KS) was once a very rare form of cancer, primarily affecting elderly men of Mediterranean and eastern European background, until the 1980s, when it began to appear among AIDS patients. It man…
Kawasaki syndrome is a potentially fatal inflammatory disease that affects several organ systems in the body, including the heart, circulatory system, mucous membranes, skin, and immune system. It occurs primarily in infants and children but has also been identified in adults as old as 34 years. Its cause is unknown. Kawasaki syndrome, also called mucocutaneous lymph node syndrome (MLNS), is an in…
Keloids are overgrowths of fibrous tissue or scars that can occur after an injury to the skin. These heavy scars are also called cheloid or hypertrophic scars. In individuals prone to keloids, even minor traumas to the skin, such as ear piercing, can cause keloids. Keloids can occur anywhere on the body, but they are most common on the earlobes, upper back, shoulders, and chest. They consist of ha…
Keratitis is an inflammation of the cornea, the transparent membrane that covers the colored part of the eye (iris) and pupil of the eye. There are many types and causes of keratitis. Keratitis occurs in both children and adults. Organisms cannot generally invade an intact, healthy cornea. However, certain conditions can allow an infection to occur. For example, a scratch can leave the cornea open…
Keratosis pilaris is a common skin condition that looks like small goose bumps, which are actually dead skin cells that build up around the hair follicle. Keratosis pilaris is a disorder that occurs around the hair follicles of the upper arms, thighs, and sometimes the buttocks. It presents as small, benign bumps or papules that are actually waxy build-ups of keratin. Normally skin sloughs off. Ho…
Kidney biopsy is a medical procedure in which a small piece of tissue is removed from the kidney for microscopic examination. The test is usually done to diagnose kidney disease and to evaluate the extent of damage to the kidney. A biopsy is also frequently ordered to detect the reason for acute renal failure when normal office procedures and tests fail to establish the cause. In addition, informa…
Kidney cancer is a disease in which the cells in certain tissues of the kidney start to grow uncontrollably and form tumors. Renal cell carcinoma, which occurs in the cells lining the kidneys (epithelial cells), is the most common type of kidney cancer. Eighty-five percent of all kidney tumors are renal cell carcinomas. Wilms' tumor is a rapidly developing cancer of the kidney most often fo…
Kidney function tests is a collective term for a variety of individual tests and procedures that can be done to evaluate how well the kidneys are functioning. The kidneys, the body's natural filtration system, perform many vital functions, including removing metabolic waste products from the bloodstream, regulating the body's water balance, and maintaining the pH (acidity/alkalinity)…
A kidney nuclear medicine scan, or study, is a simple outpatient test that involves administering small amounts of radioactive substances, called tracers, into the body and then imaging the kidneys and bladder with a special camera. The images obtained can help in the diagnosis and treatment of certain kidney diseases. While many tests, such as x rays, ultrasound exams, or computed tomography scan…
Kidney stones are solid accumulations of material that form in the tubal system of the kidney. Kidney stones cause problems when they block the flow of urine through or out of the kidney. When the stones move along the ureter, they cause severe pain. Urine is formed by the kidneys. Blood flows into the kidneys, and specialized tubes (nephrons) within the kidneys allow a certain amount of fluid fro…
Kidney transplantation is a surgical procedure to remove a healthy, functioning kidney from a living or brain-dead donor and implant it into a patient with nonfunctioning kidneys. Kidney transplantation is performed on patients with chronic kidney failure, or end-stage renal disease (ESRD). ESRD occurs when a disease or disorder damages the kidneys so that they are no longer capable of adequately …
A kidney, ureter, and bladder (KUB) x-ray study is an abdominal x ray. Despite its name, KUB does not show the ureters and only sometimes shows the kidneys and bladder and, even then, with uncertainty. An x-ray image of a human torso and abdomen showing a blocked ureter. (Custom Medical Stock Photo. Reproduced by permission.) The KUB study is a diagnostic test used to detect kidney stones a…
Kinesiology is a series of tests that locate weaknesses in specific muscles reflecting imbalances throughout the body. Then specific massages or acupressure techniques are used in an attempt to rebalance what has been revealed by the kinesiology tests. Thus, kinesiology is used as both an assessment tool and as a limited therapeutic modality. Kinesiology claims to be a healing system that detects …
Klinefelter syndrome is a chromosome disorder in males. People with this condition are born with at least one extra X chromosome. Klinefelter syndrome is a condition where one or more extra X-chromosomes are present in a male. Boys with this condition appear normal at birth. They enter puberty normally, but by mid puberty have low levels of testosterone causing small testicles and the inability to…
Kneecap removal, or patellectomy, is the surgical removal of the patella, commonly called the kneecap. Kneecap removal is done under three circumstances: A person of any age can break a kneecap in an accident. When the bone is shattered beyond repair, the kneecap is removed. No prosthesis or artificial replacement part is put in its place. Dislocation of the kneecap is most common in young girls b…
The KOH test takes its name from the chemical formula for potassium hydroxide (KOH), which is the substance used in the test. The test, which is also called a potassium hydroxide preparation, is done to rapidly diagnose fungal infections of the hair, skin, or nails. A sample of the infected area is analyzed under a microscope following the addition of a few drops of potassium hydroxide. The primar…
Korsakoff's syndrome is a memory disorder which is caused by a deficiency of vitamin B1, also called thiamine. In the United States, the most common cause of thiamine deficiency is alcoholism. Other conditions that cause thiamine deficiency occur quite rarely, but can be seen in patients undergoing dialysis (a procedure used primarily for patients suffering from kidney failure, during which…
Kyphosis is the extreme curvature of the upper back also known as a hunchback. This patient's spine shows excessive backward curvature at the level of the upper chest. (Custom Medical Stock Photo. Reproduced by permission.) The upper back bone (thoracic region), is normally curved forward. If the curve exceeds 50° it is considered abnormal (kyphotic). Kyphosis can be divided i…
Labyrinthitis is an inflammation of the inner ear that is often a complication of otitis media. It is caused by the spread of bacterial or viral infections from the head or respiratory tract into the inner ear. Labyrinthitis is characterized by dizziness or feelings of motion sickness caused by disturbance of the sense of balance. The disease agents that cause labyrinthitis may reach the inner ear…
A laceration is a wound caused by a sharp object producing edges that may be jagged, dirty, or bleeding. Lacerations most often affect the skin, but any tissue may be lacerated, including subcutaneous fat, tendon, muscle, or bone. A laceration should be repaired if it: Lacerations are less likely to become infected if they are repaired soon after they occur. Many physicians will not repair a lacer…
A lacrimal duct obstruction is blockage of the tear duct, the thin channel that normally drains tears from the surface of the eye. The lacrimal glands, located above each eyeball, produce tears. The tears flow over the eye, then drain through the nasolacrimal ducts. A tiny hole at the inner edge of each eyelid marks the opening of the ducts, which lead to the lacrimal sacs located on the side of t…
The enzyme lactate dehydrogenase (also known as lactic dehydrogenase, or LDH) is found in the cells of almost all body tissues. The enzyme is especially concentrated in the heart, liver, red blood cells, kidneys, muscles, brain, and lungs. The total LDH can be further separated into five components or fractions labeled by number: LDH-1, LDH-2, LDH-3, LDH-4, and LDH-5. Each of these fractions, call…
Lactate dehydrogenase, also called lactic dehydrogenase, or LDH, is an enzyme found in the cells of many body tissues, including the heart, liver, kidneys, skeletal muscle, brain, red blood cells, and lungs. It is responsible for converting muscle lactic acid into pyruvic acid, an essential step in producing cellular energy. Lactic dehydrogenase is present in almost all body tissues, so the LDH te…
Lactation is the medical term for breastfeeding, a natural method of feeding an infant from birth to the time he or she can eat solid food. Human milk contains the ideal amount of nutrients for the infant, and provides important protection from diseases through the mother's natural defenses. Early in a woman's pregnancy her milk-producing glands begin to prepare for her baby's…
Lactic acid is an acid produced by cells during chemical processes in the body that do not require oxygen (anaerobic metabolism). Anaerobic metabolism occurs only when too little oxygen is present for the more usual aerobic metabolism (oxygen requiring). Lactic acid is a contributing factor in muscle cramps. It is also produced in tissues when conditions such as heart attack or shock reduce the bl…
Lactose intolerance refers to the inability of the body to digest lactose. Lactose is the form of sugar present in milk. The enzyme lactase, which is normally produced by cells lining the small intestine, breaks down lactose into substances that can be absorbed into the bloodstream. When dairy products are ingested, the lactose reaches the digestive system and is broken down by lactase into the si…
Laparoscopy is a type of surgical procedure in which a small incision is made, usually in the navel, through which a viewing tube (laparoscope) is inserted. The viewing tube has a small camera on the eyepiece. This allows the doctor to examine the abdominal and pelvic organs on a video monitor connected to the tube. Other small incisions can be made to insert instruments to perform procedures. Lap…
Laryngeal cancer is cancer of the larynx or voice box. The larynx is located where the throat divides into the esophagus and the trachea. The esophagus is the tube that takes food to the stomach. The trachea, or windpipe, takes air to the lungs. The area where the larynx is located is sometimes called the Adam's apple. The larynx has two main functions. It contains the vocal cords, cartilag…
Laryngectomy is the partial or complete surgical removal of the larynx, usually as a treatment for cancer of the larynx. Normally a laryngectomy is performed to remove tumors or cancerous tissue. In rare cases, it may be done when the larynx is badly damaged by gunshot, automobile injuries, or similar violent accidents. Laryngectomies can be total or partial. Total laryngectomies are done when can…
Laryngitis is caused by inflammation of the larynx, resulting in hoarseness of the voice. When air is breathed in (inspired), it passes through the nose and the nasopharynx or through the mouth and the oropharynx. These are both connected to the larynx, a tube made of cartilage. The vocal cords, responsible for setting up the vibrations necessary for speech, are located within the larynx. The air …
Laryngoscopy refers to a procedure used to view the inside of the larynx (the voice box). The purpose and advantage of seeing inside the larynx is to detect tumors, foreign bodies, nerve or structural injury, or other abnormalities. Two methods allow the larynx to be seen directly during the examination. In one, a flexible tube with a fiber-optic device is threaded through the nasal passage and do…
Laser (light amplification by stimulated emission of radiation) surgery uses an intensely hot, precisely focused beam of light to remove or vaporize tissue and control bleeding in a wide variety of non-invasive and minimally invasive procedures. Laser surgery is used to: Anyone who is thinking about having laser surgery should ask his doctor to: Because some lasers can temporarily or permanently d…
Laxatives are products that promote bowel movements. Laxatives are used to treat constipation—the passage of small amounts of hard, dry stools, usually fewer than three times a week. Before recommending use of laxatives, differential diagnosis should be performed. Prolonged constipation may be evidence of a significant problem, such as localized peritonitis or diverticulitis. Complaints of …
Lead poisoning occurs when a person swallows or inhales lead in any form. The result can be damage to the brain, nerves, and many other parts of the body. Acute lead poisoning, which is relatively rare, occurs when a large amount of lead is taken into the body over a short period of time. Chronic lead poisoning, which is a common problem in children, occurs when small amounts of lead are taken in …
Learning disorders are academic difficulties experienced by children and adults of average to above-average intelligence. People with learning disorders have difficulty with reading, writing, mathematics, or a combination of the three. These difficulties significantly interfere with academic achievement or daily living. Learning disorders, or disabilities, affect approximately 2 million children b…
Leeches are bloodsucking worms with segmented bodies. They belong to the same large classification of worms as earthworms and certain oceanic worms. Leeches can primarily be found in freshwater lakes, ponds, or rivers. They range in size from 0.2 in (5 mm) to nearly 18 in (45 cm) and have two characteristic suckers located at either end of their bodies. Leeches consume the blood of a wide variety …
Legionnaires' disease is a type of pneumonia caused by Legionella bacteria. The bacterial species responsible for Legionnaires' disease is L. pneumophila. Major symptoms include fever, chills, muscle aches, and a cough that is initially nonproductive. Definitive diagnosis relies on specific laboratory tests for the bacteria, bacterial antigens, or antibodies produced by the body�…
Leishmaniasis refers to several different illnesses caused by infection with an organism called a protozoan. Protozoa are considered to be the most simple organisms in the animal kingdom. They are all single-celled. The types of protozoa which cause leishmaniasis are carried by the blood-sucking sandfly. The sandfly is referred to as the disease vector, simply meaning that the infectious agent (th…
Leprosy is a slowly progressing bacterial infection that affects the skin, peripheral nerves in the hands and feet, and mucous membranes of the nose, throat, and eyes. Destruction of the nerve endings causes the the affected areas to lose sensation. Occasionally, because of the loss of feeling, the fingers and toes become mutilated and fall off, causing the deformities that are typically associate…
