A hyphema is an accumulation of blood in the front (anterior) chamber of the eye. It is usually caused by blunt eye trauma. The anterior chamber (AC) is located behind the front of the eye. The AC is filled with a fluid called aqueous humor. This fluid helps form a cushion for the eye and provides an important route for nutrient and waste transport. Contusive forces from high velocity projectiles …
Hypnotherapy is the treatment of a variety of health conditions by hypnotism or by inducing prolonged sleep. Pioneers in this field, such as James Braid and James Esdaile discovered that hypnosis could be used to successfully anesthetize patients for surgeries. James Braid accidentally discovered that one of his patients began to enter a hypnotic state while staring at a fixed light as he waited f…
Hypocalcemia, a low bood calcium level, occurs when the concentration of free calcium ions in the blood falls below 4.0 mg/dL (dL=one tenth of a liter). The normal concentration of free calcium ions in the blood serum is 4.0–6.0 mg/dL. Calcium is an important mineral for maintaining human helath. It is not only a component of bones and teeth, but is also essential for normal blood clotting …
Hypochondriasis is a mental disorder characterized by excessive fear of or preoccupation with a serious illness, despite medical testing and reassurance to the contrary. It was formerly called hypochondriacal neurosis. Although hypochondriasis is often considered a disorder that primarily affects adults, it is now increasingly recognized in children and adolescents. In addition, hypochondriasis ma…
The condition called hypoglycemia is literally translated as low blood sugar. Hypoglycemia occurs when blood sugar (or blood glucose) concentrations fall below a level necessary to properly support the body's need for energy and stability throughout its cells. Carbohydrates are the main dietary source of the glucose that is manufactured in the liver and absorbed into the bloodstream to fuel…
Hypogonadism is the condition more prevalent in males in which the production of sex hormones and germ cells are inadequate. Gonads are the organs of sexual differentiation—in the female, they are ovaries; in the male, the testes. Along with producing eggs and sperm, they produce sex hormones that generate all the differences between men and women. If they produce too little sex hormone, th…
Hypokalemia is a condition of below normal levels of potassium in the blood serum. Potassium, a necessary electrolyte, facilitates nerve impulse conduction and the contraction of skeletal and smooth muscles, including the heart. It also facilitates cell membrane function and proper enzyme activity. Levels must be kept in a proper (homeostatic) balance for the maintenance of health. The normal conc…
Hypolipoproteinemia (or hypolipidemia) is the lack of fat in the blood. Although quite rare, hypolipoproteinemia is a serious condition. Blood absorbs fat from food in the intestine and transports it as a combined package with proteins and other chemicals like cholesterol. Much of the fat goes straight into the liver for processing. The cholesterol, a waste product, ends up in the bile. The protei…
The normal concentration of sodium in the blood plasma is 136–145 mM. Hyponatremia occurs when sodium falls below 130 mM. Plasma sodium levels of 125 mM or less are dangerous and can result in seizures and coma. Sodium is an atom, or ion, that carries a single positive charge. The sodium ion may be abbreviated as Na+ or as simply Na. Sodium can occur as a salt in a crystalline solid. Sodium…
Hypoparathyroidism is the result of a decrease in production of parathyroid hormones by the parathyroid glands located behind the thyroid glands in the neck. The result is a low level of calcium in the blood. Parathyroid glands consist of four pea-shaped glands located on the back and side of the thyroid gland. The gland produces parathyroid hormone which, along with vitamin D and calcitonin, are …
Hypophysectomy or hypophysis is the removal of the pituitary gland. The pituitary gland is in the middle of the head. Removing this master gland is a drastic step that was taken in the extreme circumstance of two cancers that had escaped all other forms of treatment. Cancers of the female breast and male prostate grow faster in the presence of sex hormones. It used to be that sex hormones could be…
Hypopituitarism is loss of function in an endocrine gland due to failure of the pituitary gland to secrete hormones which stimulate that gland's function. The pituitary gland is located at the base of the brain. Patients diagnosed with hypopituitarism may be deficient in one single hormone, several hormones, or have complete pituitary failure. The pituitary is a pea-sized gland located at t…
Hypospadias is a congenital defect, primarily of males, in which the urethra opens on the underside (ventrum) of the penis. The corresponding defect in females is an opening of the urethra into the vagina and is rare. Epispadias (also called bladder exstrophy) is a congenital defect of males in which the urethra opens on the In hypospadias, the urethra opens along the penile shaft rather than …
Hypotension is the medical term for low blood pressure. The pressure of the blood in the arteries rises and falls as the heart and muscles handle demands of daily living, such as exercise, sleep and stress. Some healthy people have blood pressure well below the average for their age, even though they have a completely normal heart and blood vessels. This is often true of athletes who are in superi…
Hypothermia, a potentially fatal condition, occurs when body temperature falls below 95°F (35°C). Although hypothermia is an obvious danger for people living in cold climates, many cases have occurred when the air temperature is well above the freezing mark. Elderly people, for instance, have succumbed to hypothermia after prolonged exposure to indoor air temperatures of 50–65…
Hypothyroidism, or underactive thyroid, develops when the thyroid gland fails to produce or secrete as much thyroxine (T4) as the body needs. Because T4 regulates such essential functions as heart rate, digestion, physical growth, and mental development, an insufficient supply of this hormone can slow life-sustaining processes, damage organs and tissues in every part of the body, and lead to life-…
Hypotonic duodenography is an x-ray procedure that produces images of the duodenum. The duodenum is the first part of the small intestine. Hypotonic duodenography may be ordered to detect tumors of the head of the pancreas or the area where the pancreatic and bile ducts meet the small intestine. Lesions causing upper abdominal pain may be demonstrated by duodenography, and the procedure can aid in…
Hysterectomy is the surgical removal of the uterus. In a total hysterectomy, the uterus and cervix are removed. In some cases, the fallopian tubes and ovaries are removed along with the uterus (called hysterectomy with bilateral salpingo-oophorectomy). In a subtotal hysterectomy, only the uterus is removed. In a radical hysterectomy, the uterus, cervix, ovaries, oviducts, lymph nodes, and lymph ch…
The term "hysteria" has been in use for over 2,000 years and its definition has become broader and more diffuse over time. In modern psychology and psychiatry, hysteria is a feature of hysterical disorders in which a patient experiences physical symptoms that have a psychological, rather than an organic, cause; and histrionic personality disorder characterized by excessive emotions, …
Hysterosalpingography is a procedure where x rays are taken of a woman's reproductive tract after a dye is injected. Hystero means uterus and salpingo means tubes, so hysterosalpingography literally means to take pictures of the uterus and fallopian tubes. This procedure may also be called hysterography (or HSG). Hysterosalpingography is used to determine if the fallopian tubes are open, or…
Hysteroscopy is a procedure that allows a physician to look through the vagina and neck of the uterus (cervix) to inspect the cavity of the uterus. A telescope-like instrument called a hysteroscope is used. Hysteroscopy is used as both a diagnostic and a treatment tool. Diagnostic hysteroscopy may be used to evaluate the cause of infertility, to determine the cause of repeated miscarriages, or to …
Hysterosonography, which is also called sonohysterography, is a new noninvasive technique that involves the slow infusion of sterile saline solution into a woman's uterus during ultrasound imaging. Hysterosonography allows the doctor to evaluate abnormal growths inside the uterus; abnormalities of the tissue lining the uterus (the endometrium); or disorders affecting deeper tissue layers. H…
Derived from the Greek word meaning fish disease, ichthyosis is a congenital (meaning present at birth) dermatological (skin) disease that is represented by thick, scaly skin. The ichthyoses are a group of genetic skin diseases caused by an abnormality in skin growth that results in drying and scaling. There are at least 20 types of ichthyosis. Ichthyosis can be more or less severe, sometimes accu…
The term idiopathic means "cause unknown." The idiopathic infiltrative lung diseases, also known as interstitial lung diseases, are a group of more than a hundred disorders seen in both adults and (less often) in children, whose cause is unknown but which tend to spread, or "infiltrate" through much or all of the lung tissue. They range from mild conditions that respond…
This syndrome includes a group of disorders characterized by blood and protein in the urine and by damage to the kidney glomeruli (filtering structures) that may lead to kidney failure. This syndrome, also known as Berger's disease or IgA nephropathy, arises when internal kidney structures called glomeruli become inflamed and injured. It can occur at any age, but the great majority of patie…
Idiopathic thrombocytopenic purpura, or ITP, is a bleeding disorder caused by an abnormally low level of platelets in the patient's blood. Platelets are small plate-shaped bodies in the blood that combine to form a plug when a blood vessel is injured. The platelet plug then binds certain proteins in the blood to form a clot that stops bleeding. ITP's name describes its cause and two …
Ileus is a partial or complete non-mechanical blockage of the small and/or large intestine. There are two types of intestinal obstructions, mechanical and non-mechanical. Mechanical obstructions occur because the bowel is physically blocked and its contents can not pass the point of the obstruction. This happens when the bowel twists on itself (volvulus) or as the result of hernias, impacted feces…
Immobilization refers to the process of holding a joint or bone in place with a splint, cast, or brace. This is done to prevent an injured area from moving while it heals. Splints, casts, and braces support and protect broken bones, dislocated joints, and such injured soft tissue as tendons and ligaments. Immobilization restricts motion to allow the injured area to heal. It can help reduce pain, s…
These tests evaluate the immune system, whose function is to defend the body against such invaders as bacteria and viruses. The immune system also plays a role in the control of cancer, and is responsible for the phenomena of allergy, hypersensitivity, and rejection problems when organs or tissue are transplanted. One of the ways the immune system protects the body is by producing proteins called …
Immunodeficiency disorders are a group of disorders in which part of the immune system is missing or defective. Therefore, the body's ability to fight infections is impaired. As a result, the person with an immunodeficiency disorder will have frequent infections that are generally more severe and last longer than usual. The immune system is the body's main system to fight infections.…
Immunoelectrophoresis, also called gamma globulin electrophoresis, or immunoglobulin electrophoresis, is a method of determining the blood levels of three major immunoglobulins: immunoglobulin M (IgM), immunoglobulin G (IgG), and immunoglobulin A (IgA). Immunoelectrophoresis is a powerful analytical technique with high resolving power as it combines separation of antigens by electrophoresis with i…
Immunoglobulin deficiency syndromes are a group of immunodeficiency disorders in which the patient has a reduced number of or lack of antibodies. Immunoglobulins (Ig) are antibodies. There are five major classes of antibodies: IgG, IgM, IgA, IgD, and IgE. All antibodies are made by B-lymphocytes (B-cells). Any disease that harms the development or function of B-cells will cause a decrease in the a…
Immunologic therapy is the treatment of disease using medicines that boost the body's natural immune response. Immunologic therapy is used to improve the immune system's natural ability to fight such diseases as cancer, hepatitis and AIDS. These drugs may also be used to help the body recover from immunosuppression resulting from such treatments as chemotherapy or radiation therapy. …
Immunosuppressant drugs, also called anti-rejection drugs, are used to prevent the body from rejecting a transplanted organ. When an organ, such as a liver, a heart or a kidney, is transplanted from one person (the donor) into another (the recipient), the immune system of the recipient triggers the same response against the new organ it would have to any foreign material, setting off a chain of ev…
An impacted tooth is any tooth that is prevented from reaching its normal position in the mouth by tissue, bone, or another tooth. The teeth that most commonly become impacted are the third molars, also called wisdom teeth. These large teeth are the last to develop, beginning to form when a person is about nine years old, but not breaking through the gum tissue until the late teens or early twenti…
Impedance phlebography is a noninvasive test that uses electrical monitoring to measure blood flow in veins of the leg. Information from this test helps a doctor to detect deep vein thrombosis (blood clots or thrombophlebitis). Impedance phlebography may be done in order to: Blood clots in the legs can lead to more serious problems. If a clot breaks loose from a leg vein, it may travel to the lung…
Impetigo refers to a very localized bacterial infection of the skin. There are two types, bullous and epidemic. Impetigo is a contagious bacterial skin infection that mostly affects the area around the nose and mouth. Usually caused by staphylococci, this person's impetigo was triggered by herpes simplex. (Photo Researchers, Inc. Reproduced by permission.) Impetigo is a skin infectio…
The implantable cardioverter-defibrillator is an electronic device to treat life-threatening heartbeat irregularities. It is surgically implanted. The implantable cardioverter-defibrillator is used to detect and stop serious ventricular arrhythmias and restore a normal heartbeat in people who are at high risk of sudden death. The American Heart Association recommends that implantable cardioverter-…
Impotence, often called erectile dysfunction, refers to the male's inability to achieve or maintain an erection long enough to engage in sexual intercourse. Under normal circumstances, when a man is sexually stimulated, his brain sends a message down the spinal cord and into the nerves of the penis. The nerve endings in the penis release chemical messengers called neurotransmitters that sig…
Impulse control disorders are characterized by an inability to resist the impulse to perform an action that is harmful to one's self or others. This is a relatively new class of personality disorders. The most common of these are intermittent explosive disorder, kleptomania, pyromania, compulsive gambling disorder, and trichotillomania. All of these impulse control disorders involve the los…
In vitro fertilization (IVF) is a procedure in which eggs (ova) from a woman's ovary are removed. They are fertilized with sperm in a laboratory procedure, and then the fertilized egg (embryo) is returned to the woman's uterus. IVF is one of several assisted reproductive techniques (ART) used to help infertile couples to conceive a child. If after one year of having sexual intercours…
Inclusion conjunctivitis is an inflammation of the conjunctiva (the membrane that lines the eyelids and covers the white part, or sclera, of the eyeball) by Chlamydia trachomatis. Chlamydia is a sexually transmitted organism. Inclusion conjunctivitis, known as neonatal inclusion conjunctivitis in the newborn and adult inclusion conjunctivitis in the adult, is also called inclusion blennorrhea, chl…
A cervix (the structure at the bottom of the uterus) that is incompetent is abnormally weak, and therefore it can gradually widen during pregnancy. Left untreated, this can result in repeated pregnancy losses or premature delivery. Incompetent cervix is the result of an anatomical abnormality. Normally, the cervix remains closed throughout pregnancy until labor begins. An incompetent cervix gradua…
Indigestion, which is sometimes called dyspepsia,is a general term covering a group of nonspecific symptoms in the digestive tract. It is often described as a feeling of fullness, bloating, nausea, heartburn, or gassy discomfort in the chest or abdomen. The symptoms develop during meals or shortly afterward. In most cases, indigestion is a minor problem that often clears up without professional tr…
A scanning procedure in which a patient's white blood cells are first labeled with the radioactive substance indium, and then the patient's body is scanned as a way of tracking the white blood cells at the site of possible infection. The procedure is used to detect inflammatory processes in the body such as infections. By labelling the leukocytes (white blood cells), radiologists or …
Induction of labor involves using artificial means to assist the mother in delivering her baby. Labor is brought on, or induced, when the pregnancy has extended significantly beyond the expected delivery date and the mother shows no signs of going into labor. Generally, if the unborn baby is more than two weeks past due, labor will be induced. In most cases, a mother delivers her baby between 38 a…
Infant massage refers to massage therapy as specifically applied to infants. In most cases, oil or lotion is used as it would be on an adult subject by a trained and licensed massage therapist. Medical professionals caring for infants might also use massage techniques on infants born prematurely, on those with motor or gastrointestinal problems, or on those who have been exposed to cocaine in uter…
Infectious arthritis, which is sometimes called septic arthritis or pyogenic arthritis, is a serious infection of the joints characterized by pain, fever, occasional chills, inflammation and swelling in one or more joints, and loss of function in the affected joints. It is considered a medical emergency. Infectious arthritis can occur in any age group, including newborns and children. In adults, i…
Infection control refers to policies and procedures used to minimize the risk of spreading infections, especially in hospitals and health care facilities. The purpose of infection control is to reduce the occurrence of infectious diseases. These diseases are usually caused by bacteria or viruses and can be spread by human-to-human contact, animal-to-human contact, human contact with an infected su…
Infectious mononucleosis is a contagious illness caused by the Epstein-Barr virus, which can affect the liver, lymph nodes, and oral cavity. While mononucleosis is not usually a serious disease, its primary symptoms of fatigue and lack of energy can linger for several months. Infectious mononucleosis, frequently called "mono" or the "kissing disease," is caused by the E…
Infertility is the failure of a couple to conceive a pregnancy after trying to do so for at least one full year. In primary infertility, pregnancy has never occurred. In secondary infertility, one or both members of the couple have previously conceived, but are unable to conceive again after a full year of trying. Currently, in the United States, about 20% of couples struggle with infertility at a…
Infertility drugs are medicines that help bring about pregnancy. Infertility is the inability of a man and woman to achieve pregnancy after at least a year of having regular sexual intercourse without any type of birth control. There are many possible reasons for infertility, and finding the most effective treatment for a couple may involve many tests to find the problem. For pregnancy to occur, t…
Infertility is the inability of a man and a woman to conceive a child through sexual intercourse. There are many possible reasons for the problem, which can involve the man, the woman, or both partners. Various treatments are available that enable a woman to become pregnant; the correct one will depend on the specific cause of the infertility. Infertility treatment is aimed at enabling a woman to …
Usually referred to as the flu or grippe, influenza is a highly infectious respiratory disease. The disease is caused by certain strains of the influenza virus. When the virus is inhaled, it attacks cells in the upper respiratory tract, causing such typical flu symptoms as fatigue, fever and chills, a hacking cough, and body aches. Influenza victims are also susceptible to potentially life-threate…
Inhalation therapies are a group of respiratory, or breathing, treatments designed to help restore or improve breathing function in patients with a variety of diseases, conditions, or injuries. The treatments range from at-home oxygen therapy for patients with chronic obstructive pulmonary disease to mechanical ventilation for patients with acute respiratory failure. Inhalation therapies usually i…
Insecticide poisoning is exposure to a group of chemicals designed to eradicate insects that cause affected persons to develop clinical signs that can progress to death. Insecticides belong to a group of chemicals called organophosphates, used to protect against insects. Their use is popular since they are effective and do not remain in the environment, disintegrating within a few days. Organophos…
Insomnia is the inability to obtain an adequate amount or quality of sleep. The difficulty can be in falling asleep, remaining asleep, or both. People with insomnia do not feel refreshed when they wake up. Insomnia is a common symptom affecting millions of people that may be caused by many conditions, diseases, or circumstances. Sleep is essential for mental and physical restoration. It is a cycle…
Intermittent explosive disorder (IED) is a mental disturbance that is characterized by specific episodes of violent and aggressive behavior that may involve harm to others or destruction of property. Usually, these episodes follow minor incidents and are out of proportion to the trigger. The Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) decribes intermittent explosive…
Intersex states are conditions in which a newborn's sex organs (genitals) look unusual, making it impossible to identify the sex of the baby from their outward appearance. All developing babies start out with external sex organs that look female. If the baby is male, the internal sex organs mature and begin to produce the male hormone testosterone. If the hormones reach the tissues correctl…
An IUD is an intrauterine device made of plastic and/or copper that is inserted into the womb (uterus) by way of the vaginal canal. One type releases a hormone (progesterone), and is replaced each year. The second type is made of copper and can be left in place for five years. The most common shape in current use is a plastic "T" which is wrapped with copper wire. IUDs are used to pr…
