Telogen Effluvium

Excerpt

Telogen effluvium is a form of nonscarring alopecia characterized by diffuse, often acute, hair shedding. Another form that is chronic with a more insidious onset also exists. Telogen effluvium is the excessive shedding of resting or telogen hair after some metabolic stress, hormonal changes, or medication. Telogen hair is also known as club hair due to the shape of the root. In a normal, healthy individual's scalp, about 85% is anagen hair, and 15% is telogen hair. Anagen hair is actively growing hair, whereas telogen hair is resting hair. A few hairs may also be in the catagen or transition phase. A hair follicle typically produces anagen hair for almost 4 years and then rests for about 4 months. A new anagen hair grows under the resting telogen hair and pushes it out. If the body remains under significant stress, approximately 70% of anagen hair precipitates into the telogen phase, thus causing hair loss.

Telogen effluvium is a reactive process triggered by metabolic stress, hormonal changes, or medications. Common triggering events include acute febrile illness, severe infection, major surgery, severe trauma, postpartum hormonal changes (particularly a decrease in estrogen), hypothyroidism, discontinuing estrogen-containing medication, crash dieting, low protein intake, heavy metal ingestion, and iron deficiency. Many medications have been linked to telogen effluvium, but the most common are beta-blockers and retinoids, including excess vitamin A, anticoagulants, propylthiouracil, carbamazepine, and immunizations.