Online Medical Dictionary

Letter L

L: Abbreviation for litre.
Labia: Lips, either regarding the oral labia (lips of the mouth) or the labia majora and labia minora (external lips of the female genitalia).
Labial: Regarding the lips.
Labile Diabetes: An unstable diabetes wherein the individual's glucose levels oscillate, often without explanation, which can result in hyperglycemia or ketosis. More often occurs in individuals with diabetes type 1 but can also occur in individuals with diabetes type 2. Also called brittle diabetes.
Labour: Childbirth; the delivering of an infant from the uterus of a female characterized by three stages. Stage 1: dilation of the cervix; Stage 2: birth of the infant; and Stage 3: afterbirth of the placenta.
Laceration: A jagged, tear-like wound.
Lacrimal Gland: Almond-shaped glands situated in the eye which function to secrete aqueous tear film, which is passed through canal to the lacriminal sac and drained as tears.
Lactic Acidosis: Acidosis (low pH in the blood and body tissues; high acidity) with a buildup of lactate in the body, caused by hypoxia, a lack of oxygen being delivered to cells, which can occur in conjunction with vigorous exercise, shock, diabetes mellitus and with other conditions and certain medications, causing cells to anaerobically metabolize glucose. Symptoms produced include nausea, abdominal pain and irregular breathing.
Lactose: A disaccharide sugar composed of glucose and galactose, found in milk.
Lactose Intolerance: Lack of the digestive enzyme lactase needed to metabolize lactose, thus the digestive system's ability to digest lactose is impeded.
Lacuna: A gap. For example, lacunar amnesia regards a gap in memory of a specific time.
LAM: Abbreviation for lymphangioleiomyomatosis.
Laminectomy: A surgical procedure in which the lamina, a portion of the vertebral bone of the spine, is removed in order to relieve pressure on or decompress the soft tissues of the spinal canal, to treat spinal stenosis; to alter the contour of the vertebral column; or to allow deeper access to spinal tissues.
Landau-Kleffner Syndrome: A neurological disorder appearing with rare occurrence in children, marked by a progressive onset of aphasia (the loss of comprehension or ability to participate in language) due to affects on the Broca area and Wernicke area of the brain; occasionally causing seizures.
Laparoscopy: A diagnostic or surgical procedure in which a telescopic larascope or digital larascope are inserted through the addominal wall to view or treat conditions of the pelvis or abdomen.
Laparotomy: An exploratory or therapeutic surgical procedure performed in the abdominal cavity through the abdominal wall. May be used when a condition in the abdomen has been identified, such as colon cancer or peptic ulcer.
Large Cell Carcinoma: Malignant neoplasm groups forming from the epithelial cells of the lungs.
Large Cell Lymphoma: A grouping of lymphoma cancers characterized by cells of a large diameter. The most common of the large cell lymphomas are the B cell lymphomas, while less common lymphoma cancers, such as anaplastic large cell lymphoma, involve the T cells.
Laryngeal Palsy: Paralysis of the super laryngeal nerve or its branches, the external and internal laryngeal nerves. Such paralysis can affect pitch and impede certain vocal capabilities. Laryngeal palsy may occur as a result of trauma or an injury that occurred during a thyroidectomy procedure.
Laryngeal Papilloma: A rare condition induced by an HPV virus of the throat, causing the formation of various benign tumours on the larynx or along the respiratory tract which, if left untreated, could obstruct airways. Laryngeal papilloma may continually grow back and necessitate numerous tumour removal surgeries or antiviral treatments.
Laryngectomy: The surgical removal of the larynx, conducted when chemotherapy or radiation therapy cannot remove cancer from the larynx in its entirety. The individual is given an airway through which to breath in the front of the neck, called a stoma and usually a voice prosthesis through which to provide vocal functions.
Laryngitis: Inflammation of the larynx, the respiratory tract segment that contains the vocal cords, causing hoarseness, complete lack of voice or other dysphonia due to irritation.
Larynx: The segment of the respiratory tract located between the trachea and pharnyx. Also termed the voice box for its function to produce sound through the manipulation of pitch and volume.
Larynx Transplant: The surgical replacement of a diseased or cancerous larynx with a vocal prosthesis.
Latent: Dormant. A latent virus or other pathology is present but not acting or apparent, though the potential for it to become so does exist.
Lateral: Referring to or situated at the side.
Lavage: A process used to cleanse, such as in an antiseptic lavage or a ductal lavage.
Leiomyoma: A non-malignant neoplasm of smooth muscle, which can develop in any organ but most commonly appears in the uterus or small bowel.
Leiomyosarcoma (LMS): A malignant neoplasm of smooth muscle, rare and usually treatable by surgical removal of the tumour and radiation therapy or chemotherapy to treat any remaining cancerous cells.
Lennox-Gastaut Syndrome: A form of epilepsy apparent in childhood marked by various and frequent seizures, psychological and behavioural abnormalities and, often, mental retardation.
Lens: A transparent eye structure, capable of altering its shape to accommodate focal distances so that items may appear clear at various distances. With the cornea, the lens also functions to refract light that is focused on the retina.
Lesion: The broad term used to describe any abnormality of tissue caused from disease or tissue. A lesion is described by its cause and shape. For example, a malignant lesion is used to describe such that has been caused by cancerous tumour.
Lethal: Capable of causing fatality.
Lethargy: A mental or physical state of fatigue, tiredness, weariness, languor or exhaustion.
Leukemia: A hematologic neoplasm; a cancer of the blood or bone marrow causing the production of an abnormal amount of white blood cells, or leukocytes, to be present in the body. There are many types and forms of leukemia both acute and chronic, with varying causes and prognosis.
Leuko-: Prefix defining white.
Leukocyte Count: White blood cell count. This count can be an indication of disease or other condition. A drop in blood white blood cell count to low limit is termed leukopenia, while a rise in white blood cell count to upper limit is termed leukocytosis.
Leukocytes: White blood cells of the immune system, present in the blood and lymphatic system, which function to alert and defend the body from foreign pathogens.
Leukocytosis: An elevated white blood cell count above that which is normal, which may be due to any of several factors, including: bacterial infection, asthma, parasitic infection, chronic infection or viral infection.
Leukodystrophy: Disorders, usually inherited, caused by the impeded growth or development of the myelin sheath, the fatty insulator of nerve endings. Leukodystrophies cause the progressive degenerating of the brain's white matter, causing impairment in movement, speech, appetite and behaviour.
Leukopenia: Lower white blood cell levels than is normal, which increases the risk of the onset of an infection. Leukopenia can be brought on by several different conditions, including influenza, leukemia, therapies to treat cancer, Hodgkin's lymphoma, mineral deficiency and others.
Leukoreduction: The process by which white blood cells are removed from blood or blood components to ready the volume for transfusion.
Life Support: Any therapy or device used to sustain an individual's life while their present state or condition impedes their body from doing so. These therapies can include dialysis, feeding tubes, cardiopulmonary resuscitation, bypass, catheterization, pacemaker and defibrillation.
Lifetime Risk: The assessed potential an individual or group possesses for developing a condition or disease. For instance, the overall lifetime risk of developing ovarian cancer for females is 1.6 per cent.
Ligament: The fibrous tissue acting as connector between body structures, such as two connecting bones.
Limb: Referring to an arm or leg.
Lingual: Regarding the tongue.
Lipids: A term used to describe the naturally occurring molecules that compose fats (the lipid subgroup triglycerides), sterols, vitamins A, D, E and K, and waxes, among other composites.
Lipoma: A benign fatty tumour.
Liposarcoma: A malignant tumour that develops out of the fat cells of deep soft tissues.
Liposuction: The cosmetic surgical removal of fat from various areas of the body. Also called lipoplasty.
Listeria: A genus of bacteria rarely affecting humans.; Prefix defining stone.
Lithotomy: The invasive surgical procedure to removal bodily-formed stones that cannot pass through the body naturally, such as those that may develop in the kidney, bladder or gallbladder.
Lithotripsy: The non-invasive procedure in which bodily-formed stones, such as those that may develop in the bladder, gallbladder or kidney, or broken down by means of acoustic pulse, probe or ultrasound wave so that the individual may be able to pass them naturally.
Liver: The large, multi-functioning organ vital in many bodily processes including protein synthesis, producing bile to aid in the digestion process, detoxification and hormone production.
Liver Biopsy: A procedure conducted to retrieve a small sample of the liver, used to attain the diagnosis of a liver disease, to determine the course of a liver disease, or to monitor the affect a treatment is having on a diseased liver.
Liver Disease: Any disease affecting the liver organ. Liver disease often occurs in conjunction with elevated levels of bilirubin in the blood, inducing jaundice. Liver disease includes cirrhosis, hepatitis infectious, liver cancer, and metabolic disorders. Liver disease is largely influenced by the consumption of alcohol.
Liver Spot: A flat, pigmented blemish associated with sun exposure and aging. Commonly found on the backs of hands, arms and face. Benign in nature.
Liver Transplant: The surgical removal of a diseased liver and replacement with the healthy liver of a donor. Also called hepatic transplantation. Liver transplant may be conducted to correct any acute or chronic liver dysfunction, accept where absolute contraindications exist that would render the transplant ineffective, such as septic infection, surrounding cancer, or alcohol abuse.
Lobectomy: The surgical removal of the lobe of an organ such as that of the lungs, thyroid or brain. Usually conducted when cancerous cells or tumour have been detected in the lobe of an organ, but have not yet metastasized beyond the lobe.
Lobstein Disease: Osteogenesis imperfecta, a genetic bone condition of many types causing the impeded or lack of ability to produce connective tissue due to a deficiency in type-1 collagen. Lobstein disease induces a blue sclera (whites of the eyes) and bone fragility. Treatment aims to strengthen the bones through physiotherapy, drug course, and/or surgery. Also called brittle bone disease.
Local Therapy: Treatment affecting only a specified, target area.
Local Treatment: Treatment affecting only a specified, target area.
Locked-in Syndrome: A neurological condition in which all voluntary muscles are gripped in paralysis, except those controlling eye movement. In total locked-in syndrome the eye muscles are also paralyzed. Locked-in syndrome usually involves a cerebrovascular accident, or stroke affecting lesion in the brain stem and damage to the ventral portion of the brain's pons. The individual, though completely paralyzed, remains mentally alert. Various methods can be used to aid the individual's ability to communicate, though the significant return of any motor ability is very rare.
Lockjaw: See Tetanus.
Lordosis: The inward curvature of a segment of the vertebral column of the spine, caused naturally by differences in the thickness of the anterior and posterior sections of the intervertebral disc.
Lou Gehrig Disease: Amyotrophic lateral sclerosis (ALS), a progressive, and fatal, neurodegenerative disease caused by the degeneration of nerve cells of the central nervous system, the motor neurons. In the onset Lou Gehrig disease causes overall muscle weakness, and gradually leads to the inability to conduct most motor functions. While a minority of ALS cases are believed to be hereditary, the majority of onsets occur for reasons unknown, though some neurotoxic compounds are suspected to be associated with the disease.
Low Blood Pressure: See Hypotension.
Low Blood Sugar: See Hypoglycemia.
Low-grade Lymphoma: A lymphoma with slow to develop and metastasize. Also termed indolent lymphoma.
Lumen: The space within a bodily tubular structure, tract, cavity or cell.
Lung Cancer: Malignant induction of the uncontrolled growth of tissues of the lung, usually incited by a carcinoma developed from the lung's epithelial cells. The onset of lung cancer is associated with many factors, such as smoking, asbestos exposure, genetic susceptibility and exposure to radon gas. The two major types of lung cancer vary in treatment methods. Chemotherapy and radiation therapy have been found to have greater affect on small cell lung carcinoma; non-small cell lung carcinoma has been found to respond better, in some cases, to surgical treatment. Lung cancer is responsible for the greatest number of cancer-related deaths.
Lung Volume Reduction Surgery: The surgical removal of a damaged portion of lung conducted to allow the remaining, somewhat healthy, lung tissue room to expand, aimed to improve breathing capacity. Conducted in some cases of emphysema or with chronic obstructive pulmonary disease.
Lung Transplant: The surgical replacement of all or a portion of a diseased lung or lungs with the healthy lung(s) of a donor. Conducted on individuals with end-stage pulmonary conditions. Also termed pulmonary transplantation.
Lupus: Systemic lupus erythematosus (SLE), a chronic autoimmune disease affecting soft tissue, marked by recurrent flares and periods of remission. The body's immune system is induced by the disease to attack its own cells and tissues, resulting in inflammation, harmful to the kidneys, nervous system, heart, lungs, skin and joints. The majority of Canadians diagnosed with lupus achieve a high rate of survival through treatment aimed at ceasing or preventing the severity of lupus flares. The general cause of lupus remains unknown, though some environmental triggers and genetic predispositions are believed to be associated with the autoimmune disease.
Lymphadenopathy: Swollen lymph nodes. The enlargement of the lymph nodes may be due to infection, malignancy or disease.
Lymphedema: Tissue swelling caused by a compromised lymphatic system's return of fluid to the thoracic duct, through which it is secreted into the blood stream and back into tissue, increasing risk of infection. Lymphdema can be induced by radiation therapy, surgery in which lymph nodes are removed (such as in treatment of breast cancer), or may be genetically attributed.
Lymphoma: A cancerous tumour of the lymphoid cells and tissue of the immune system. Several forms and classifications of lymphoma exist. Most of these lymphoma can be treated with chemotherapy, or in some cases bone marrow transplantation in combination with radiation therapy may be necessitated.