Androgenic alopecia (AGA) in women

Female pattern hair loss is a common condition characterized by a diffuse reduction in hair density over the crown and frontal scalp with retention of the frontal hairline.

• FPHL is now the preferred term for androgenic alopecia (AGA) in women (1)
• the prevalence and severity increases with advancing age (2)
  • prevalence in the UK and USA studies in Caucasian women show similar frequencies, increasing from 3% to 6% in women aged under 30 years to 29 to 42% in women aged 70 and over
  • oriental women have a lower frequency of androgenetic alopecia than women of European origin (2)

The exact aetiology of female pattern hair loss (FPHL) is not known

• there is a progressive miniaturization of hairs, resulting in loss of hair density and widening of the midline part clinically
• in contrast to male-pattern hair loss, the androgenic nature of FPHL is not clear and women often have normal hormonal profiles and no other signs of androgenization
• hypothesized that FPHL has a polygenetic mode of transmission
  • it is thought that early- and late-onset female AGA are genetically distinct (2)

Most women present with a history of gradual thinning of scalp hair, often over a period of several years

• hair loss can start at any time between early teens and late middle age - however hair loss may precede pubarche and menarche (1)
• frequently a history of excessive hair shedding, but unlike telogen effluvium, hair thinning is usually noticed from the outset

Pattern of hair loss

• examination of the scalp shows three different patterns:
  • diffuse thinning of the crown region with preservation of the frontal hairline - two scales can be used to describe this pattern
    • the commonly used 3-point Ludwig scale
    • the 5-point Sinclair scale
  • thinning and widening of the central part of the scalp with breach of frontal hairline (christmas tree pattern) - assessed by Olsen scale
  • thinning associated with bitemporal recession - Hamilton-Norwood type (2)
• in some women the hair loss may affect a quite small area of the frontal scalp whereas in others the entire scalp is involved, including the parietal and occipital regions
• although many women develop a minor degree of postpubertal recession at the temples whether or not they have diffuse hair loss

Diagnosis

• usually straightforward but other causes of diffuse hair loss may need to be excluded, particularly when the hair loss progresses rapidly
  • occasionally, systemic lupus erythematosus can also present in this way
  • in alopecia areata there may be hair loss in other sites
  • hypothyroidism is also in the differential

Management

• antiandrogens and topical minoxidil have been used in the management of this condition (3)

Reference:

• (1) Dinh QQ. Sinclair R. Female pattern hair loss: current treatment concepts. Clin Interv Aging. 2007;2(2):189-99.
• (2) Blume-Peytavi U et al. S1 guideline for diagnostic evaluation in androgenetic alopecia in men, women and adolescents. Br J Dermatol. 2011;164(1):5-15
• (3) Sinclair R, Wewerinke M, Jolley D. Treatment of female pattern hair loss with oral antiandrogens. Br. J. Dermatol. 2005; 152: 466-73.