Labyrinthitis is an inflammation of the inner ear that is often a complication of infection of the middle ear (otitis media). It is usually caused by the spread of bacterial or viral infections from the head or respiratory tract into the inner ear.


Lactation refers to the formation of milk in the breasts during the period following childbirth. Breastfeeding is the process of the infant obtaining milk by suckling at the breast.

Lactose Intolerance

Lactose intolerance refers to the inability of the body to digest lactose.

Language Delay

A language delay is language development that is significantly below the norm for a child of a specified age.

Language Development

Language development is the process by which children come to understand and communicate language during early childhood.

Language Disorders

A language disorder is a deficit or problem with any function of language and communication.


Saline cathartics include dibasic sodium phosphate (Phospo-Soda), magnesium citrate, magnesium hydroxide (milk of magnesia), magnesium sulfate (Epsom salts), sodium biphosphate, and others. They act by attracting and holding water in the intestinal lumen, and may produce a watery stool.

Lead Poisoning

Lead poisoning occurs when a person swallows, absorbs, or inhales lead in any form. The result can be damaging to the brain, nerves, and many other parts of the body.

Learning Disorders

Learning disorders are academic difficulties experienced by children and adults of average to above-average intelligence. People with learning disorders have difficulty with reading, writing, mathematics, or a combination of the three.

Leukemias, Acute

Leukemia is a cancer that starts in the organs that make blood, namely the bone marrow and the lymph system. Depending on their characteristics, leukemias can be divided into two broad types.

Leukemias, Chronic

Chronic leukemia is a disease in which abnormal, cancerous white blood cells are made in the bone marrow. Depending on the type of white blood cell that is involved, chronic leukemia can be classified as chronic lymphocytic leukemia or chronic myeloid leukemia.

Lice Infestation

A lice infestation, or pediculosis, is caused by parasites living on human skin. Lice are tiny, wingless insects with sucking mouthparts that feed on human blood and lay eggs on body hair or in clothing.


Lipidoses are genetic disorders, passed from parents to their children, characterized by defects of the digestive system that impair the way the body uses dietary fat. When the body is unable to properly digest fats, lipids accumulate in body tissues in abnormal amounts.


A lisp is a functional speech disorder that involves the inability to correctly pronounce one or more sibilant consonant sounds, usually s or z.


Listeriosis is an illness caused by the bacterium Listeria monocytogenes that is acquired by eating contaminated food. The organism can spread to the blood stream and central nervous system.


A lie is any deliberate deviation from the truth; it is a falsehood communicated with the intention to mislead or deceive.

Lyme Disease

Lyme disease is an inflammatory disease transmitted through the bite of a deer tick carrying the spiral-shaped bacterium Borrelia burgdorferi. Symptoms can include skin rash, joint inflammation, fever, headache, fatigue, and muscle pain.


Lymphadenitis is the inflammation of lymph nodes. It is often a complication of bacterial infections, although it can also be caused by viruses or other disease agents.