Dictionary

winter depression See seasonal affective disorder.

windpipe See trachea.

Wilson disease An inherited disorder of copper metabolism that results in an abnormal accumulation of copper in the body. Although the accumulation of copper begins at birth, symptoms of the disorder do not appear until later in life, between the ages of 6 and 40. A diagnostic feature of the disease is a Kayser-Fleischer ring,…

Wilms tumor A childhood form of kidney cancer with a peak age of occurrence at 3 years of age. It is sometimes associated with abnormalities of the urinary tracts or other birth defects. Some cases are related to defects in one of two genes referred to as Wilms’ tumor 1 (WT1) or Wilms’ tumor 2…

whooping cough See pertussis.

WHO World Health Organization.

whitehead A familiar term for what is medically called a closed comedo. A comedo, the primary sign of acne, consists of a dilated (widened) hair follicle filled with keratin squamae (skin debris), bacteria, and sebum (oil). A whitehead is a comedo that has an obstructed opening to the skin. A closed comedo may rupture and…

white subungual onychomycosis, proximal See onychomycosis, proximal white subungual.

white spots on the nails See jogger’s nails.

white matter The part of the brain that contains myelinated nerve fibers. The white matter is white because it is the color of myelin, the insulation that covers nerve fibers.

white coat hypertension A transient increase in blood pressure (hypertension) that is triggered by the sight of medical personnel in white coats (or other attire). Ideally, people so affected should do their best to relax when in the medical office.

white blood cell count The number of white blood cells (WBCs) in the blood. The normal range for the WBC count varies among laboratories but is usually between 4,300 and 10,800 cells per cubic millimeter. It can be expressed in international units as (4.3–10.8)×109 cells per liter. A low WBC count is called leukopenia. A…