Medical terms - Letter L (page 6) | MedicalVocabulary.org

Leukemia, smoldering

A condition in which the bone marrow does not function normally. It does not produce enough blood cells. This condition may progress and become acute leukemia. Smoldering leukemia also is called myelodysplastic syndrome…
Leukemia, t(8;21)

Leukemia with a translocation (an exchange of material) between chromosomes 8 and 21. Seen characteristically in acute myeloid leukemia (AML) -- acute nonlymphocytic leukemia (ANLL), usually the M2 type. The breakpoints…
Leukemic reticuloendotheliosis

See: Hairy cell leukemia
Leukemoid reaction

A benign condition in which the high number of white blood cells found in a blood test resembles the numbers seen in leukemia. For example, infectious mononucleosis can return blood-test results with a leukemoid reaction
Leuko-

Prefix meaning white, as in leukocyte (white blood cell). Leuko- comes from the Greek 'leukos' meaning white. Leuco- is an alternate spelling. Thus, a leukocyte = a leucocyte
Leukocoria

A white pupillary reflex. When one shines a bright light on the pupil, it normally appears red. In leukocoria, the light makes the pupil look white. This occurs with a number of eye diseases including congenital…
Leukocyte count

A white blood cell (WBC) count.
Leukocyte, granular

A type of white blood cell filled with microscopic granules (tiny sacs) containing enzymes that digest microorganisms. Granular leukocytes -- they are better known as granulocytes -- are part of the innate immune system…
Leukocyte,eosinophilic

See: Eosinophil
Leukocytes

Cells that help the body fight infections and other diseases. Also called white blood cells (WBCs).
Leukocytosis

Increase in the number of white blood cells.
Leukodystrophy

A disorder of the white matter of the brain, the part of the brain that contains myelinated nerve fibers. The white matter is white because it is the color of myelin, the insulation covering the nerve fibers. (The white…
Leukoencephalopathy with vanishing white matter

White matter: An inherited brain disease that occurs mainly in children. and follows a chronic progressive course with additional episodes of rapid deterioration following stress from febrile infection or minor head…
Leukomalacia, cystic periventricular

Softening of the white matter near the ventricles of the brain resulting in abnormal cysts. Cystic periventricular leukomalacia is a major problem in very premature infants. Treating the mother with a cortisone-like…
Leukopenia

Lower than the normal amount of white blood cells.
Leukoplakia

Leukoplakia: A white spot or patch on the mucous membranes in the mouth (for instance, inside the cheeks, on the gums or the tongue) that may become cancerous.
Leukoreduction

A process used to filter and remove white blood cells from whole blood before transfusion. The reason why white blood cells (leukocytes) are removed from blood is because they provide no benefit to the recipient but can…
Leukotriene

One of a group of hormones that cause the symptoms of hayfever and asthma. Derived from arachidonic acid, the leukotrienes act by mediating immediate hypersensitivity. Leukotriene modifiers that prevent the production…
Level 1 biosafety

>Level 1 -- This level applies to agents that do not ordinarily cause human disease. >Level 2 -- This level is appropriate for agents that can cause human disease, but whose potential for transmission is limited. >Level…
Level 2 biosafety

>Level 1 -- This level applies to agents that do not ordinarily cause human disease. >Level 2 -- This level is appropriate for agents that can cause human disease, but whose potential for transmission is limited. >Level…
Level 3 biosafety

>Level 1 -- This level applies to agents that do not ordinarily cause human disease. >Level 2 -- This level is appropriate for agents that can cause human disease, but whose potential for transmission is limited. >Level…
Level 4 biosafety

>Level 1 -- This level applies to agents that do not ordinarily cause human disease. >Level 2 -- This level is appropriate for agents that can cause human disease, but whose potential for transmission is limited. >Level…
Levite

A member of an ancient caste of hereditary Jewish priests. Membership in the Levites is determined by paternal descent. The Levites have traditionally been considered the descendants of Levi, a son of Jacob. However…
Levo-

Abbreviated LAAM. An alternative to methadone. See: LAAM.
Levo-alpha acetyl methadol

Abbreviated LAAM. An alternative to methadone. See: LAAM
Levocardia

Reversal of all of the abdominal and thoracic organs (situs inversus) except the heart, which is still in its usual location on the left. Levocardia virtually always rerflects the presence of congenital heart disease…
Levonorgestrel

A progestin. Named levonorgestrel because it is the levorotatory form of norgestrel. Used in combination with an estrogen as an oral contraceptive. Used alone for emergency contraceptive (in Plan B) and the treatment of…
Levothyroxine

See: Thomas, Lewis.
Lewis Thomas

See: Thomas, Lewis
Lewis, Edward B

(1918-2004) American geneticist and Nobel Laureate who showed how genes control embryonic development. In 1957 Lewis discovered that genes were arranged on chromosomes in the same order as they were activated along the…
LFCN

Lateral femoral cutaneous nerve. See also: Meralgia paresthetica
LGV

Lymphogranuloma venereum
Lhermitte sign

Sudden transient electric-like shocks extending down the spine triggered by flexing the head forward. Due to a disorder such as compression of the cervical spine (the portion of the spinal cord within the neck). One…
LHRH agonist

A compound that is similar to LHRH (luteinizing hormone-releasing hormone) in structure and is able to act like it. Luteinizing hormone-releasing hormone is a naturally occurring hormone that controls sex hormones in…
Li-Fraumeni syndrome (LFS)

This is an extraordinary cancer family syndrome. People with LFS have a tendency to develop a great diversity of tumors. LFS was first discovered in 1969. By reviewing the medical records and death certificates of…
Libido

1. Sexual drive. 2. In psychoanalysis, the psychic energy from all instinctive biological drives. Libido in Latin means 'desire, longing, fancy, lust, or rut.' Although the adjective libidinous, meaning lustful, has…
Library

In genetics, a library is an unordered collection of clones (i.e., cloned DNA from a particular organism), whose relationship to each other can be established by physical mapping. For example, you can have an E. coli…
Library of Medicine, National (NLM)

The world's largest medical library, the U.S. National Library of Medicine (NLM) is part of the National Institutes of Health (NIH). The NLM has as its mission to collect, organize, and make available biomedical science…
Library, arrayed

In genetics, arrayed libraries of DNA clones are used for many purposes, including screening for a specific gene or genomic region of interest as well as for physical mapping. An arrayed library consists of (in…
Library, cDNA

A collection of DNA sequences generated from mRNA (messenger RNA) sequences. This type of DNA library contains only DNA that codes for proteins and does not include any non-coding DNA
Library, genomic

A collection of DNA clones made from a set of randomly generated overlapping DNA fragments representing the entire genome of an organism. As a molecular genetic sequel to John Steinbeck's 'Of Mice and Men', today you…
Lice, head

See: Head lice
Lice, pubic

See: Pubic lice
Licensed clinical social worker

A social worker trained in psychotherapy who helps individuals deal with a variety of mental health and daily living problems to improve overall functioning. A social worker usually has a master's degree in social work…
Lichen planus

Lichen planus: A common skin disease with small itchy pink or purple spots on the arms or legs. The lesions (abnormal areas) on the skin in lichen planus are typically polygonal, flat (hence, the term planus), and…
Lichenification

Thick, leathery skin, usually the result of constant scratching and rubbing. With prolonged rubbing or scratching, the outer layer of the skin (the epidermis) becomes hypertrophied (overgrown) and this results in…
Lichtenberg figures

A fern-leaf pattern of reddish, painless marks on the skin that are a result of a skin reaction to a lightening strike. The pattern typically vanishes in a few hours or days. Lichtenberg figures are named after Georg…
Life support

1. A therapy or device designed to preserve someone's life when an essential bodily system is not doing so. Life support may, for example, involve enteric feeding (by a tube), total parenteral nutrition, mechanical…
Life-support

A disease associated with the way a person or group of people lives. Lifestyle diseases include atherosclerosis, heart disease, and stroke; obesity and type 2 diabetes; and diseases associated with smoking and alcohol…
Lifestyle disease

A disease associated with the way a person or group of people lives. Lifestyle diseases include atherosclerosis, heart disease, and stroke; obesity and type 2 diabetes; and diseases associated with smoking and alcohol…