Definition When patients cannot use their gastrointestinal tracts for nutrition, parenteral nutrition may be used to maintain or improve the patient's nutritional status. This form of intravenous treatment provides all the nutrients that are delivered to the patient. This treatment may be temporary or long-term. Purpose The harmful effects of malnutrition on the overall health of a patient...

Definition Pyruvate kinase deficiency (PKD) is part of a group of disorders called hereditary nonspherocytic hemolytic anemias. Hereditary nonspherocytic anemias are rare genetic conditions that affect the red blood cells. PKD is caused by a deficiency in the enzyme, pyruvate kinase. Although PKD is the second most common of the hereditary nonspherocytic anemias, it is...

Definition Pyloroplasty is an elective surgical procedure in which the lower portion of the stomach, the pylorus, is cut and resutured, to relax the muscle and widen the opening into the intestine.Pyloroplasty is a treatment for high-risk patients for gastric or peptic ulcer disease. A peptic ulcer is a well-defined sore on the stomach where the lining of the stomach or duodenum has been eaten away...

Definition Pyloric stenosis is a disorder that occurs when the pyloric sphincter muscle, which is found at the outlet of the stomach, thickens and becomes enlarged causing the cavity (lumen) of the pylorus to narrow and lengthen. This blocks the passage of food from the stomach to the small intestine (the portion of bowel that continues digestion after food leaves the stomach). Description Pyloric stenosis occurs...

Definition Pyelonephritis is an inflammation of the kidney and upper urinary tract that usually results from noncontagious bacterial infection of the bladder (cystitis ). Description Acute pyelonephritis is most common in adult females but can affect people of either sex and any age. Its onset is usually sudden, with symptoms that often are mistaken as the results of straining the lower back. Pyelonephritis often...

Definition Pulmonary valve stenosis is a congenital heart defect in which blood flow from the heart to the pulmonary artery is blocked. Description Pulmonary valve stenosis is an obstruction in the pulmonary valve, located between the right ventricle and the pulmonary artery. Normally, the pulmonary valve opens to let blood flow from the right...

Definition Pulmonary valve insufficiency is a disorder involving a defect of the valve located in the pulmonary artery. Description This disorder is also known as pulmonary valve regurgitation or pulmonary incompetence. The pulmonary valve is the structure in the pulmonary artery consisting of three flaps, which open and close during...

Definition Pulmonary hypertension is a rare lung disorder characterized by increased pressure in the pulmonary artery. The pulmonary artery carries oxygen-poor blood from the lower chamber on the right side of the heart (right ventricle) to the lungs where it picks up oxygen. Description Pulmonary hypertension is present when the blood pressure in the circulation of the lungs...

Definition Pulmonary function tests are a group of procedures that measure the function of the lungs,revealing problems in the way a patient breathes. These tests can determine the cause of shortness of breath and may help confirm the diagnosis of lung diseases, such as asthma, chronic bronchitis, or emphysema. Th e tests may also be performed before any major lung surgery to make sure the person will not be...

Definition Pulmonary fibrosis is a lung disease characterized by scarring of the deep tissue of the lungs. Description Pulmonary fibrosis belongs to a broad group of lung diseases called “interstitial lung diseases” that includes more than 130 disorders characterized by scarring (fibrosis) and/or inflammation of the lungs. The lungs are a pair of organs located in the chest. They...

Definition A pulmonary embolism occurs when a lung artery is blocked by a blood clot. The blockage is often caused by one or more blood clots that travel to the lungs from another part of the body. Description A pulmonary embolism is a problem of the vascular system, the network of blood vessels that includes the arteries, veins and capillaries that carry blood to and...

Definition Pulmonary edema is a condition in which fluid accumulates in the lungs, usually because the heart's left ventricle does not pump adequately. Description The build-up of fluid in the spaces outside the blood vessels of the lungs is called pulmonaryedema. Pulmonary edema is a common complication of heart disorders, and most cases of the condition are associated with heart...

Definition Pulmonary artery catheterization is a diagnostic procedure in which a small catheter is inserted through a neck, arm, chest, or thigh vein and maneuvered into the right side of the heart, in order to measure pressures at different spots in the heart. Purpose Pulmonary artery catheterization is performed to: ·         evaluate heart...

Definition Pulmonary alveolar proteinosis (PAP) is a rare disease of the lungs. Description In this disease, also called alveolar proteinosis or phospholipidosis, gas exchange in the lungs is progressively impaired by the accumulation of phospholipids, compounds widely found in other living cells of the body. The alveoli are filled with this substance that renders them less effective...

Definition Puerperal infection is a bacterial infection that occurs following childbirth. The diagnostic criteria require that the childbearing woman have a temperature over 100.4°F (38°C) on any two of the first 10 postpartum days after day one, or over 101.5°F (38.6°C) during the first 24 hours. Description The incidence of puerperal infection is...

Puberty is the period of sexual maturity when sexual organs mature and secondary sexual characteristics develop. Puberty is also the second major growth period of life—the first being infancy. A number of hormones under the control of the hypothalamus, pituitary, ovaries, and testes regulate this period of sexual growth, which begins for most boys and girls between the ages of nine and 15...

Definition Ptosis is the term used for a drooping upper eyelid. Ptosis, also called blepharoptosis, can affect one or both eyes. Description The eyelids serve to protect and lubricate the outer eye. The upper eyelid is lifted by a muscle called the levator muscle. Inside the back part of the lid is a tarsal plate which adds rigidity to the lid. The levator muscle is attached to the tarsal plate by...

Definition Psychosurgery involves severing or otherwise disabling areas of the brain to treat a personality disorder, behavior disorder, or other mental illness. Modern psychosurgical techniques target the pathways between the limbic system (the portion of the brain on the inner edge of the cerebral cortex) that is believed to regulate emotions, and the frontal cortex, where thought processes are seated. Purpose Lobotomy...

Definition A psychosocial disorder is a mental illness caused or influenced by life experiences, as well as maladjusted cognitive and behavioral processes. Description The term psychosocial refers to the psychological and social factors that influence mental health. Social influences such as peer pressure, parental support, cultural and religious background, socioeconomic status, and interpersonal...

Definition Psychoses are conditions characterized by loss of contact with reality and disordered thinking processes, such as delusions—a firm belief in the false or impossible—and hallucinations—seeing or hearing things that others cannot see or hear. Description People with psychoses are referred to as being psychotic. In addition to delusions and/or hallucinations they may be paranoid—unreasonably...

Definition Psychological tests are written, visual, or verbal evaluations administered to assess the cognitive and emotional functioning of children and adults. Purpose Psychological tests are used to assess a variety of mental abilities and attributes, including achievement and ability, personality, and neurological functioning. Achievement and ability tests For children, academic achievement,...

Definition Psychoanalysis is a form of psychotherapy used by qualified psychotherapists to treat patients who have a range of mild to moderate chronic life problems. It is related to a specific body of theories about the relationships between conscious and unconscious mental processes, and should not be used as a synonym for psychotherapy in general. Psychoanalysis is done one-on-one with the...

Definition Psychiatric confinement is the use of restraints to detain a person in need of care and further evaluation. Purpose The purpose of restraint and confinement are crucial since they have a medico legal implication. The primary purpose for such intervention is typically an urgent or emergent condition that could cause danger to the affected person or others, or cause severe disability...

Definition Psoriatic arthritis is a form of arthritic joint disease associated with the chronic skin scaling and fingernail changes seen in psoriasis. Description Physicians recognize a number of different forms of psoriatic arthritis. In some patients, the arthritic symptoms will affect the small joints at the ends of the fingers and toes. In others, symptoms will affect joints on one...

Definition Named for the Greek word psōra meaning itch, psoriasis is a chronic, non-contagious disease characterized by inflamed lesions covered with silvery-white scabs of dead skin. Description Normal skin cells mature and replace dead skin every 28 to 30 days. In psoriasis, the immune system triggers the immune system to make T cells, a type of white blood cell, that cause skin cells...

Definition Pseudoxanthoma elascticum (PXE) is an inherited connective tissue disorder in which the elasticfibers present in the skin, eyes, and cardiovascular system gradually become calcified and inelastic. Description PXE was first reported in 1881 by Rigal, but the defect in elastic fibers was described in1986 by Darier, who gave the...

Definition A pseudomonas infection is caused by a bacterium, Pseudomonas aeruginosa, and may affect any part of the body. In most cases, however, pseudomonas infections strike only persons who are very ill, usually hospitalized. Description P. aeruginosa is a rod-shaped organism that can be found in soil, water, plants, and animals. Because it rarely causes disease in...

  Definition Pseudogout is a form of arthritis that causes pain, redness, and inflammation in one or more joints. Description Pseudogout is also known by another name: calcium pyrophosphate dihydrate deposition disease (CPPD), the basis of which is derived from the calcium deposits that collect in the joint. The deposits or crystals, as they are sometimes called, cause pain and inflammation...

Definition The proton pump inhibitors are a group of drugs that reduce the secretion of gastric (stomach) acid. They act by binding with the enzyme H+, K(+)-ATPase, hydrogen/potassium adenosine triphosphatase, which is sometimes referred to as the proton pump. This enzyme causes parietal cells of the stomach lining to produce acid. Although they perform much the same functions...

  Definition The prothrombin time test belongs to a group of blood tests that assess the clotting ability of blood. The test is also known as the pro time or PT test. Purpose The PT test is used to monitor patients taking certain medications as well as to help diagnose clotting disorders. Diagnosis Patients who have problems with delayed blood clotting are given a number of tests...

Definition Protein-energy malnutrition (PEM) is a potentially fatal body-depletion disorder. It is the leading cause of death in children in developing countries. Description PEM is also referred to as protein-calorie malnutrition. It develops in children and adults whose consumption of protein and energy (measured by calories) is insufficient to satisfy the body's nutritional needs....

Definition Electrophoresis is a technique used to separate different elements (fractions) of a blood sample into individual components. Serum protein electrophoresis (SPEP) is a screening test that measures the major blood proteins by separating them into five distinct fractions: albumin, alpha1, alpha2, beta, and gamma proteins. Protein electrophoresis can also be performed...

Definition Protein components tests measure the amounts and types of protein in the blood. Proteins are constituents of muscle, enzymes, hormones, transport proteins, hemoglobin, and other functional and structural elements of the body. Albumin and globulin make up most of the protein within the body and are measured in the total protein of the blood and other body fluids....

Definition A protease inhibitor is a type of drug that cripples the enzyme protease. An enzyme is a substance that triggers chemical reactions in the body. The human immunodeficiency virus (HIV) uses protease in the final stages of its reproduction (replication) process. Purpose The drug is used to treat selected patients with HIV infection. Blocking protease interferes...

Definition Prostatitis is an inflammation of the prostate gland, a common condition in adult males. Often caused by infection, prostatitis may develop rapidly (acute ) or slowly (chronic ). Description Prostatitis may be the symptom-producing disease of the genitourinary tract for which men most often seek medical help. About 40% of visits to a specialist in genitourinary problems...

Definition Prostatectomy is surgical removal of part of the prostate gland (transurethral resection, a procedure performed to relieve urinary symptoms caused by benign enlargement), or all of the prostate (radical prostatectomy, the curative surgery most often used to treat prostate cancer ). Purpose Benign disease When men reach their mid-40s, the prostate gland begins to enlarge. This condition,...

Definition A prostate ultrasound is a diagnostic test used to detect potential problems with a man's prostate. An ultrasound test involves very high-frequency sound waves that pass through the body. The pattern of reflected sound waves, or "echoes," shows the outline of the prostate. This test can show whether the prostate is enlarged, and whether an...

Definition Prostate-specific antigen, or PSA, is a protein produced by the prostate gland that may be found in elevated levels in the blood when a person develops certain diseases of the prostate, notably prostate cancer. PSA is specific, because it is present only in prostate tissue. It is not specific for prostate cancer, however, as it may also be elevated in men with benign enlargement...

Definition Prostate cancer is a disease in which cells in the prostate gland become abnormal and start to grow uncontrollably, forming tumors. Description Prostate cancer is a malignancy of one of the major male sex glands. Along with the testicles and the seminal vesicles, the prostate secretes the fluid that makes up semen....

Definition Prostate biopsy is a surgical procedure to remove small samples of prostate tissue for microscopic examination. The prostate gland lies just below the urinary bladder and surrounds the urethra. The gland produces enzyme-rich secretions that contribute to the seminal fluid via ducts that enter the urethra. Purpose A prostate biopsy is usually performed to...

Definition A prophylaxis is a measure taken to maintain health and prevent the spread of disease. Antibiotic prophylaxis is the focus of this article and refers to the use of antibiotics to prevent infections. Purpose Antibiotics are well known for their ability to treat infections. But some antibiotics also are prescribed to prevent infections. This usually is done only in...

Definition Prolonged QT syndrome, also known as long QT syndrome (LQTS), refers to a group of disorders that increase the risk for sudden death due to an abnormal heartbeat. Description Abnormal heartbeats (cardiac arrhythmias ) are a primary cause of sudden death, especially in the young population. In the United States, an estimated 1 in 300,000 individuals per...

Definition Prolactin is a hormone secreted by the anterior portion of the pituitary gland (sometimes called the "master gland"). Its role in the male has not been demonstrated, but in females, prolactin promotes lactation, or milk production, after childbirth. Purpose The prolactin test is used to diagnose pituitary dysfunction that might be caused by a tumor...

Definition Progressive supranuclear palsy (PSP; also known as Steele-Richardson-Olszewski syndrome) is a rare disease that gradually destroys nerve cells in the parts of the brain that control eye movements, breathing, and muscle coordination. The loss of nerve cells causes palsy, or paralysis, that slowly gets worse as the disease progresses. The palsy affects ability to move the...

Definition Progressive multifocal leukoencephalopathy is a rare, fatal disease of the white matter of the brain that almost solely strikes individuals who already have weakened immune systems. Description In progressive multifocal leukoencephalopathy, myelin (the substance that wraps around nerve fibers, providing insulation and speeding nerve transmission) is progressively destroyed....

Definition Proctitis is an inflammation of the rectum. Description Proctitis affects mainly adolescents and adults. It is most common in men around age 30. Proctitisis caused by several different sexually transmitted diseases. Male homosexuals and people who practice anal intercourse are more likely to suffer from proctitis. Patients who have AIDS or who are immunocompromised are...

Definition Primary biliary cirrhosis is the gradual destruction of the biliary system for unknown reasons. Description Although the cause of this serious condition is not known, it has many features to suggest that it is an autoimmune disease. Autoimmunity describes the process whereby the body's defense mechanisms are turned against itself. The immune system is supposed to recognize...

Definition Prickly heat is a common disorder of the sweat glands characterized by a red, itching , prickling rash following exposure to high environmental temperatures. Description Prickly heat is also known as heat rash, sweat retention syndrome, and miliaria rubra. This disorder occurs during the summer months or year-round in hot, humid climates, and is caused by blockage...

Definition Priapism is a prolonged, sustained erection of the penis that occurs in the absence of sexual excitation and which may last hours to days, with or without pain . Description The penis has two cavities, called the “corpora cavernosa,” which run the length of the organ and are filled with spongy tissue. Blood flows in and fills the open spaces in the spongy tissue to create...

Definition The term presbyopia means "older eye," and is a vision condition involving the loss of the eye's ability to focus on close objects. Description Presbyopia is a condition that occurs as a part of normal aging. The condition develops gradually over a number of years. Symptoms are usually noticeable by age 40 to 45, and continue to develop until the process stabilizes...