Chronic telogen effluvium and androgenetic alopecia are two forms of chronic hair loss. Their origin is primarily hormonal but can, in some cases, be nutritional or metabolic.
Summary
Unlike with reactional hair loss, which generally appears three to four months after a triggering factor, hair loss is considered chronic when it progresses over the course of at least six months. The scientific term for this condition is chronic telogen effluvium. Thyroid disorders, anorexia, iron deficiency (with or without anemia) as well as certain medicinal treatments (retinoids, anticoagulants, antihypertensive drugs, anticonvulsants, etc.) are among the causes. This type of hair loss leads to a shorter anagen phase, which in turn leads to shorter hair that goes through the hair cycle faster and falls out more often.
Hair loss in chronic telogen effluvium is less significant than in acute telogen effluvium (occasional hair loss). The latter generally manifests sporadically over the course of several years in middle-aged women who had thick, shiny hair originally. They complain of reduced length and volume.
What is androgenetic alopecia? Chronic hair loss is characterized by episodes of hair loss eventually leading to a miniaturization of the hair and a reduction in hair density. It affects mostly men at 70% to 80% versus 29% to 42% of women* over their lifetime, and is typically observed in men between the ages of 30 and 40. The mechanism by which male androgenetic alopecia manifests is hormonal and involves the androgen receptors found in the dermal papilla. Hair regrowth thus speeds up: it becomes depleted and gradually thinner until it eventually falls out permanently. To date, only two medicinal treatments are indicated to slow down this chronic hair loss: minoxidil and finasteride. The first is a topical treatment. The second is an oral treatment that can be prescribed to men only. Another, more expensive solution is available: hair implants.
* Source: Blume-Peytavi et al., 2011; Norwood, 1975
