Definition 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. Hysterosonography does...

Definition Hysteroscopy enables a physician to look through the vagina and neck of the uterus (cervix) to inspect the cavity of the uterus with an instrument called a hysteroscope. Hysteroscopy is used as both a diagnostic and a treatment tool. Purpose Diagnostic hysteroscopy can be used to help determine the cause of infertility, dysfunctional uterine bleeding, and repeated miscarriages....

Definition 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). Purpose Hysterosalpingography is used to determine...

Definition The term "hysteria" has been in use for over 2,000 years and its definition has becomebroader 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, dramatics,...

Definition Hysterectomy is the surgical removal of all or part 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, which is a hysterectomy with bilateral salpingo-oophorectomy . In a subtotal hysterectomy, only the uterus is removed. In a radical hysterectomy, the uterus,...

Definition Hypotonic duodenography is an x-ray procedure that produces images of the duodenum. The duodenum is the first part of the small intestine. Purpose 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 abdominalpain may be demonstrated by duodenography,...

Definition 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...

Definition Hypothermia, a potentially fatal condition, occurs when body temperature falls below 95°F (35°C). Description 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...

Definition Hypotension is the medical term for low blood pressure. Description The pressure of the blood in the arteries rises and falls as the heart and muscles handledemands 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...

Definition 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 upper surface (dorsum) of the penis. The corresponding defect in...

Definition 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. Description The pituitary is a pea-sized...

Definition Hypophysectomy, or hypophysis, is the surgical removal of the pituitary gland.  Purpose The pituitary gland is a small, oval-shaped endocrine gland about the size of a pea located in the center of the brain above the back of the nose. Its major role is to produce hormones that regulate growth and metabolism in the body. Removing this important gland is a drastic step that is usually taken in...

Definition 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. Description 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...

Definition 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. Description 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...

  Definition Hypolipoproteinemia (or hypolipidemia) is the lack of fat in the blood. Description 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,...

Definition 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...

Definition Hypogonadism is the condition in which the production of sex hormones and germ cells (sperm and eggs) is inadequate. Description 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,...

  Definition The condition called hypoglycemia is literally translated as low blood sugar. Hypoglycemiaoccurs 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. Description Carbohydrates are the main...

Definition The primary feature of hypochondriasis is excessive fear of having a serious disease. These fears are not relieved when a medical examination finds no evidence of disease. People with hypochondriasis are often able to acknowledge that their fears are unrealistic, but this intellectual realization is not enough to reduce their anxiety. In order to qualify for a diagnosis of...

  Definition 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. Description 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...

Definition 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...

Definition A hyphema is an accumulation of blood in the front (anterior) chamber of the eye. It is usually caused by blunt eye trauma. Description 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...

Definition Cardiomyopathy is an ongoing disease process that damages the muscle wall of the lower chambers of the heart. Hypertrophic cardiomyopathy is a form of cardiomyopathy in which the walls of the heart's chambers thicken abnormally. Other names for hypertrophic cardiomyopathyare idiopathic hypertrophic subaortic stenosis and asymmetrical septal hypertrophy. Description Hypertrophic cardiomyopathy usually...

Definition Hyperthyroidism is the overproduction of thyroid hormones by an overactive thyroid gland. Description Located in the front of the neck, the thyroid gland produces the hormones thyroxine (T4) and triiodothyro-nine (T3) that regulate the body's metabolic rate by helping to form protein ribonucleic acid (RNA) and increasing oxygen absorption in every cell. In turn, the production of these hormones...

Definition Hypertension is high blood pressure. Blood pressure is the force of blood pushing against the walls of arteries. Arteries are the blood vessels that carry oxygenated blood from the heart to the body's tissues. Description As blood flows through arteries, it pushes against the inside of artery walls. The more...

Definition Hypersplenism is a type of disorder which causes the spleen to rapidly and prematurely destroy blood cells. Description The spleen is located in the upper left area of the abdomen. One of this organ's major functions is to remove blood cells from the body's bloodstream. In hypersplenism, its normal function accelerates, and it begins to automatically remove cells that may still be...

Definition Hypersensitivity pneumonitis refers to an inflammation of the lungs caused by repeatedbreathing in of a foreign substance, such an organic dust, a fungus, or a mold. The body's immune system reacts to these substances, called antigens, by forming antibodies, molecules that attack the invading antigen and try to destroy it. The combination...

  Definition Hyperpigmentation is the increase in the natural color of the skin. Description Melanin, a brown pigment manufactured by certain cells in the skin called melanocytes, is responsible for skin color. Melanin production is stimulated by a pituitary hormone called melanocyte stimulating hormone (MSH). Other pigments appear in the skin much less often. Causes and symptoms Darkened spots on...

Definition Parathyroid glands are four pea-sized glands located just behind the thyroid gland in the front of the neck. The function of parathyroid glands is to produce a hormone called parathyroid hormone (parathormone), which helps regulate calcium and phosphate in the body. Hyperparathyroidism is the overproduction of this hormone. Description Thyroid glands and parathyroid glands, despite their...

Definition Hyperopia (farsightedness) is the condition of the eye where incoming rays of light reach the retina before they converge into a focused image. Description When light goes through transparent but dense material like the materials of the eye's lens system (the lens and cornea), its velocity decreases. If the surface of the dense material is not perpendicular to the incoming light, as is the...

Definition The normal concentration of sodium in the blood plasma is 136-145 mM. Hypernatremia is defined as a serum sodium level over 145 mM. Severe hypernatremia, with serum sodium above 152 mM, can result in seizures and death. Description 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...

Definition Hyperlipoproteinemia refers to a group of acquired and inherited disorders whose common denominator is excessive levels of lipids (fats) in the blood, caused by a metabolic disorder. It is also referred to as hyperlipidemia. The condition is a major cause of coronary heart disease (CHD). Description The acquired form of hyperlipoproteinemia occurs as a condition secondary to another...

Definition The normal concentration of potassium in the serum is in the range of 3.5 to 5.0 mM. Hyperkalemia refers to serum or plasma levels of potassium ions above 5.0 mM. The concentration of potassium is often expressed in units of milliequivalents per liter (mEq/L), rather than in units of millimolarity (mM). Both units mean the same thing when applied to concentrations of potassium ions. Description A...

Definition Hyperhidrosis is a medical condition characterized by excessive sweating in the armpits, palms, soles of the feet, face, scalp, and/or torso. Description Hyperhidrosis involves sweating in excess of the amount required normally for the body's level of activity and temperature. There are two types of hyperhidrosis—primary and secondary. In primary hyperhidrosis, the cause is...

Definition Hyperemesis gravidarum means excessive vomiting during pregnancy. Description In pregnant women, nausea and vomiting (morning sickness) are common, affecting up to 80% of pregnancies. Hyperemesis, or extreme nausea and excessive vomiting, occur in about 1% of pregnancies. This condition causes uncontrollable vomiting, severe dehydration, and weight loss for...

Definition Hypercoagulation disorders (or hypercoagulable states or disorders) have the opposite effect of the more common coagulation disorders. In hypercoagulation, there is an increased tendency for clotting of the blood, which may put a patient at risk for obstruction of veins and arteries (phlebitis or pulmonary embolism). Description In normal hemostasis, or the stoppage...

Definition Hypercholesterolemia refers to levels of cholesterol in the blood that are higher than normal. Description Cholesterol circulates in the blood stream. It is an essential molecule for the human body. Cholesterol is a molecule from which hormones and steroids are made. It is also used to maintain nerve cells. Between 75 and 80% of the cholesterol that circulates in a person's bloodstream is...

Description Hypercalcemia is an abnormally high level of calcium in the blood, usually more than 10.5 milligrams per deciliter of blood. It is the most common life-threatening metabolic disorder associated with cancer. Calcium plays an important role in the development and maintenance of bones in the body. It is also needed in tooth formation and is important in other body functions. As much as 99% of the...

Definition A hyperbaric chamber is a room that allows an individual to breathe 100% pure oxygen at greater than 1 standard atmosphere of pressure. Purpose Hyperbaric chambers are used to deliver hyperbaric oxygen therapy (HBOT). HBOT was developed to treat underwater divers suffering from decompression sickness (the bends). It has since been approved by the Undersea...

  Definition Hyperaldosteronism is a disorder which is defined by the body's overproduction of aldosterone, a hormone that controls sodium and potassium levels in the blood. Its overproduction leads to retention of salt and loss of potassium, which leads to hypertension (high blood pressure). Description Also known as Conn's syndrome, primary aldosteronism, and secondary aldosteronism,...

Definition Hydrotherapy is the external use of water to improve health, relieve pain , or treat a disease or condition. Purpose Hydrotherapy is used for a wide variety of purposes. In general, it is used to treat diseases or conditions, to relieve pain, and to improve or maintain general health and well being. Hydrotherapy has a very long history. For hundreds of years people have believed...

Definition Hydronephrosis is the swelling of the kidneys when urine flow is obstructed in any of part of the urinary tract. Swelling of the ureter, which always accompanies hydronephrosis, is called hydroureter. Hydronephrosis implies that a ureter and the renal pelvis (the connection of the ureter to the kidney) are overfilled with urine. Description The kidneys filter urine out of the blood...

Definition The word hydrocephalus derives from the Greek words hydro, meaning water, and cephalus, meaning head. Hydrocephalus is the result of the excessive accumulation of fluid in the brain. Traditionally, hydrocephalus has been described as a disease characterized by increased intracranial pressure (ICP), increased cerebrospinal fluid (CSF) volume, and dilatation of...

Definition Hydrocelectomy is a surgical procedure to remove a hydrocele. A hydrocele is collected fluid in the membrane surrounding the testes. Purpose Hydrocelectomy is performed to relieve the pain or reoccurrence of a hydrocele. Normally, hydroceles are not very painful. They tend to be a soft swelling in the membrane surrounding the testes. As the hydrocele grows, the scrotum gets larger....

Definition A hydatidiform mole is a relatively rare condition in which tissue around a fertilized egg that normally would have developed into the placenta instead develops as an abnormal cluster of cells. (This is also called a molar pregnancy.) This grapelike mass forms inside of the uterus after fertilization instead of a normal embryo. A hydatidiform mole triggers a positive pregnancy test...

Huntington disease (HD), also called Huntington’s disease, is a rare, incurable genetic disease that results in the progressive degeneration of both physical and mental abilities. Huntington disease was formerly known as Huntington chorea since the most obvious symptoms involve uncontrollable body movements known as chorea. The term chorea comes from the Greek...

Definition The human leukocyte antigen test, also known as HLA, is a test that detects antigens (genetic markers) on white blood cells. There are four types of human leukocyte antigens: HLA-A, HLA-B, HLA-C, and HLA-D. Purpose The HLA test is used to provide evidence of tissue compatibility typing of tissue recipients and donors. It is also an aid in genetic...

Definition The most common test of pregnancy involves the detection of a hormone known as human chorionic gonadotropin (hCG) in a sample of blood or urine. Purpose To determine whether or not a woman is pregnant. Description Shortly after a woman's egg is fertilized by her male partner's sperm and is implanted in the lining or the womb (uterus), a placenta begins to...

Definition Human bite infections are potentially serious injuries that develop when a person's teeth break the skin of the hand or other body part and introduce saliva containing disease organisms below the skin surface. Description There are three common types of injuries caused by human bites : ·         Closed-fist injuries:...

Definition The human-potential movement is a term used for humanistic psychotherapies that first became popular in the 1960s and early 1970s. The movement emphasized the development of individuals through such techniques as encounter groups, sensitivity training, and primal therapy. Although the human-potential movement and humanistic therapy are sometimes used as synonyms,...