Alopecia Areata: A disease that causes sudden smooth, circular patches of hair loss. It is thought that it is caused by the body forming antibodies against some hair follicles. It can result from such factors as stress and genetics.
Alopecia Totalis: A condition that results in no hair on the scalp. It may begin as Alopecia areata or some other cause.
Alopecia Universalis: A condition that results in no hair on any part of the body; this includes eyelashes, eyebrows, and scalp hair. It may develop as alopecia areata or result from another cause.
Amino Acids: The building blocks of protein. A deficiency of amino acids may adversely affect hair growth.
Amortization: The process of converting one enzyme to another, such as testosterone to dihydrotestosterone.
Anagen: The growing phase of hair, usually lasting between two and six years.
Anagen Effluvium: Loss of hair that is supposed to be in the anagen or growing phase. This is the type of hair loss that is associated with chemotherapy or radiation treatment.
Androgen: general term referring to any male hormone. The major androgen is testosterone.
Androgenetic Alopecia: Hair loss resulting from a genetic predisposition to effects of dihydrotestosterone (DHT) on the hair follicles. Also termed female pattern baldness and male pattern baldness, hereditary alopecia, and common baldness.
Antiandrogen: An agent that blocks the action of androgens by preventing their attachment to receptor cells, interfering with their metabolism, or decreasing their production in the body.
Aromatase: An enzyme (actually an enzyme complex) involved in the production of estrogen that acts by catalyzing the conversion of testosterone (an androgen) to estradiol (an estrogen). Aromatase is located in estrogen-producing cells in the adrenal glands, ovaries, placenta, testicles, adipose (fat) tissue, and brain.
Autograft: A graft taken from your own body. Azelaic Acid: Azelaic acid (like Retin-A) is more commonly used in the treatment of acne and other skin conditions. It inhibits the activity of the enzyme 5 alpha-reductase, involved in the conversion of testosterone to DHT.