The progression of androgenetic alopecia

Androgenetic alopecia - when changes to the normal hair cycle cause hair loss to exceed replacement - has a classic set of symptoms

  • In men the hairline recedes at brow and temples and hair becomes thinner on the crown
  • Women experience loss of volume and reduction in hair shaft diameter around the forehead and crown

In hair loss the hair follicles shrink or miniaturise causing:

  • more to enter telogen (resting phase).
  • telogen to lengthen
  • anagen (growth phase) to shorten

Many factors can cause patients to lose their hair including:

  • medical conditions
  • prescribed medication
  • poor nutrition
  • inadequate hair care
  • severe stress
  • Surgery
  • prolonged illness

The most common cause (around 95% of hair loss cases) is hereditary hair loss or androgenetic alopecia. The exact mechanism is not fully understood but is linked to the hormone androgen. The hair follicles shrink in size and the growing phase gets shorter. The produced hair is shorter, finer and much less visible. In time some follicles will even be destroyed and therefore incapable of producing hair.

Other types of hair loss include:

Alopecia Areata: relatively uncommon, this affects men and women equally. Often experienced in childhood, it is believed to be triggered by an autoimmune response to hair follicles. It initially starts with a single patch of hair loss, which regrows in a few months. May occur more than once.

Alopecia Totalis: very rare but permanent and traumatic. All body hair is lost.

Diffuse Alopecia: a gradual thinning of hair often caused by factors such as thyroid disease, iron deficiency, hormonal changes and drugs such as anti-cancer treatments. Once the cause is treated the hair loss is reversible.