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Hair Disorders

INTRODUCTION

Key facts on hair numbers

  • Hair growth is asynchronous (i.e. continuous production and shedding)

  • Humans produce 1 km of hair per month

  • Approx. 50–100 hairs are shed daily without a reduction in density

  • The scalp contains, on average, 100 000 hair follicles

  • At least 25% of hair must be shed before a noticeable loss of density occurs

  • Hair loss counts consistently above 100/d indicate excessive hair loss

  • Significant hair loss tends to block the shower drain or be visible all over the pillow

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Table H3 Hair loss: diagnostic strategy model

Probability diagnosis

Androgenetic alopecia (male or female pattern baldness)

Alopecia areata (diffuse type)

Telogen effluvium (incl. postpartum)

Anagen effluvium (esp. cytotoxic therapy)

Serious disorders not to be missed

Infection

  • tinea capitis

  • bacterial folliculitis

  • secondary syphilis

  • post-febrile state

Cancer

  • treatment for cancer

Other

  • systemic disease (e.g. lupus)

  • scarring alopecia (e.g. lichen planopilaris)

Pitfalls (often missed)

Nutritional

  • severe dieting

  • malnutrition

  • zinc/iron deficiency

Masquerades

Drugs

Hypothyroidism

Is the patient trying to tell me something?

Emotional stress (telogen effluvium), trichotillomania

Key investigations

Consider:

  • FBE/ESR

  • pituitary hormones (FSH/LH/prolactin/FSH)

  • hair pull test

  • trichogram

  • scalp biopsy

  • skin scrapings and hair sample for fungal microscopy and culture

Causes of diffuse hair loss

  • Androgenetic alopecia

  • Telogen effluvium

  • Postpartum telogen effluvium

  • Alopecia areata (diffuse type)

  • Drugs—cytotoxics, anti-epileptics, various hormones, others

  • Hypothyroidism

  • Nutritional

    • – iron deficiency

    • – severe dieting

    • – zinc deficiency

    • – malnutrition

  • Post-febrile state

  • Anagen effluvium

ANDROGENIC ALOPECIA

This is the most common form of human hair loss affecting 50% by 40 yrs and up to 50% by 60 yrs. It is genetically determined as well as being androgen dependent. In women the pattern of hair loss is different to men. Diffuse thinning occurs on the top of the head (the crown) while the front hairline usually remains (Fig. H2).

Figure H2

Androgenic alopecia: female pattern baldness (left) and male pattern baldness

Three illustrations depict androgenic alopecia. The first illustration representing female pattern baldness shows thinning on top of the head of a female. The front hairline remains. The second illustration representing male pattern baldness shows hair loss on top of the head. The third illustration representing male pattern baldness shows hair loss on top and front of the head.
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Treatment, which is difficult, is summarised on 26.

ALOPECIA AREATA, ALOPECIA TOTALIS AND ALOPECIA UNIVERSALIS

Alopecia areata is a disorder of the hair follicle causing a sudden onset of localised or diffuse hair loss. The features are complete hair loss (small patch or diffuse), a clean normal scalp, no inflammation and exclamation-mark hairs. Small patches may recover spont. (usu. 80%), while extensive (>50% loss) has a variable course.

Alopecia totalis, which involves the total scalp, has at best a 50% chance of recovery in a fit adult. In alopecia universalis the eyebrows and eyelashes are also affected.

For treatment, see image 26.

SCARRING ALOPECIA

In this irreversible condition hair follicles are ...

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