HAIR LOSS DEFINITIONS (GLOSSARY)
Alopecia areata. Alopecia areata refers to a specific autoimmune condition where there is partial hair loss on the scalp. If an individual has some scalp hair remaining, the term alopecia areata can be used. For example, if an individual has lost 60 % of his or her scalp hair, and has lost 100 % of the eyebrow and eyelash hairs, the appropriate term is still alopecia areata. About 1.7 % of the population is affected by alopecia areata.
Alopecia totalis. An individual has alopecia totalis when all of the scalp hair has been lost, but there is still body hair in other areas. An individual with no scalp hair, and no eyebrow hair but who still retains some body hair has alopecia totalis. About 5-10 % of patients with alopecia areata will develop alopecia totalis.
Alopecia universalis. A patient is said to have alopecia universalis when all hair on the scalp and body are lost. Less than 1 % of patients with alopecia areata will develop alopecia universalis.
Anagen: refers to the growing phase of the hair cycle. Hair grows in three phases: anagen (2-6 years), catagen (transition stage, 3 weeks) and telogen (resting stage, 3 months) and then the hair fiber falls out and then cycle repeats
Androgen: a generic term referring to any of the male hormones. Testosterone and dihydrotestosterone are important male hormones
Autoimmune disease: a type of disease whereby the body's immune system is activated to attack it's own tissues.
Biopsy (scalp biopsy): a short procedure that allows a physician to remove hairs and surrounding skin for analysis.
Catagen: a short phase of the hair cycle, usually lasting 3 weeks.
Cicatricial: refers to scarring. The term is derived from the latin cicatrix meaning "scar." There are many hair loss conditions that lead to scarring and permanent hair loss. See scarring hair loss conditions
Crown: the top part of the scalp (sometimes called the vertex)
Dermal Papillae: very specialized cells at the base of the hair follicle. These cells have a key role in helping hair growth, regulating the hair cycle and ultimately the type of hair that is produced. The size of the hair fiber is known to be influenced by the size of the dermal papilla.
Donor area: the region of the body where hairs are taken during a hair transplant. The donor area is usually the back of the scalp but can be the beard, chest, arm and leg hairs.
Estrogen: one of the main female hormones.
Female pattern hair loss: a type of hair loss in women, sometimes called female thinning.
Finasteride: a medication used to treat genetic hair loss
Folliculitis: Refers to inflammation within the hair follicle
Grafts: hair follicle units moved during the course of a hair transplant
Gynecomastia: enlargement of breast tissue in men. Drugs like finasteride and dutasteride have a small risk of gynecomastia
Hamilton Norwood Scale: A common scale used to evaluate stages of balding in men
Inflammation: the response of the body to injury, foreign material, infection or during autoimmune processes. Inflammation is usually accompanied by redness, heat and sometimes tenderness in an area and an increase in the number of white blood cells in the area as well
Lichen planopilaris: A common type of scarring alopecia - see Lichen planopilaris
Miniaturization: The process by which a large hair becomes thinner and thinner over time to eventually produce a thin vellus like hair. Miniaturization of hairs is seen during genetic hair loss.
Minoxidil: a common treatment for male and female hereditary hair loss
Non-scarring: A family of hair loss conditions that do not show the precence of scarring in the skin following a scalp biopsy.
Pustule: A small collection of pus in the skin.
Rogaine: A popular brand name of minoxidil
Scarring hair loss conditions: A group of hair loss conditions associated with the development of scar tissue in the skin and around hair follicles. Scarring hair loss conditions often lead to permanent hair loss
Telogen: The final phase of the 3 part hair cycle (anagen-catagen-telogen). Following telogen phase, hairs are shed from the scalp and a new hair starts growing again.
Telogen effluvium: a form of hair loss characterized by excessive daily shedding.
Topical: applied directly to the skin or scalp (as opposed to injected or ingested)
Trichobezoar: a mass of hair trapped in the stomach and gastrointestinal system; often seen in trichotillomania
Vertex: the top part of the scalp (sometimes called the crown)