Dictionary

lb. Abbreviation for pound (for the Latin libra), a measure of weight.

LCHAD deficiency See deficiency, LCHAD.

LDL Low-density lipoprotein.

LDL cholesterol Low-density lipoprotein cholesterol, commonly referred to as “bad” cholesterol. Elevated LDL levels are associated with an increased risk of heart disease. Lipoproteins, which are combinations of fats (lipids) and proteins, are the form in which lipids are transported in the blood. Lowdensity lipoproteins transport cholesterol from the liver to the tissues of the…

lead poisoning An acute or chronic poisoning caused by the absorption of lead or any of its salts into the body. Lead poisoning is an environmental hazard that is capable of causing mental retardation, behavioral disturbance, and brain damage. Lead poisoning is formally defined in the US as at least 10 micrograms of lead per…

learning disability One of several childhood disorders characterized by difficulty with certain skills such as reading or writing in individuals with normal intelligence. Learning disorders affect the ability to interpret what one sees and hears or the ability to link information from different parts of the brain. These limitations can show up in many ways—as…

leg In popular usage, the part of the body from the top of the thigh down to the foot, and in medical terminology, the portion of the lower extremity that runs from the knee to the ankle. The leg (in the medical sense) has two bones—the tibia (shinbone) and the fibula—both of which are known…

leg, upper More properly called the thigh, the upper leg is the area between the knee and the hip. It has only one bone, the femur, which spans the distance from the hip to the knee.

Legg-Calvé-Perthes disease A hip disorder in children that is due to interruption of the blood supply to the head of the femur (the ball in the balland-socket hip joint), causing it to deteriorate. This disease is most common between ages 6 and 9, and it tends to affect boys most commonly but is more severe…

Legg-Perthes disease See Legg-Calvé-Perthes disease.

Legionella The bacterium that causes

Legionnaires’ disease A disease that is caused by bacteria found in plumbing, shower heads, and water-storage tanks. The disease was first identified at the 1976 American Legion convention, and subsequent outbreaks have occurred. The bacterium that causes it, now known as Legionella, thrives in the mist of condensers, air conditioners, and evaporative cooling towers, and…