Disorders of hair
Hair loss (alopecia)
The division of alopecia into diffuse, localized and scarring or non-scarring helps in diagnosis (Table 1).
| Type of hair loss | Causes |
|---|---|
| Diffuse non-scarring | Male pattern/female pattern, hypothyroid, hypopituitary, hypoadrenal, drug induced, iron deficiency, telogen and anagen effluvium, diffuse alopecia areata |
| Localized/non-scarring | Alopecia areata, ringworm, traumatic, hair pulling, traction, secondary syphilis |
| Localized/diffuse scarring | Burns, radiation, shingles, kerion, tertiary syphilis, lupus erythematosus, morphoea, pseudopelade, lichen planus |
Diffuse non-scarring
Male and female patterns (androgenetic alopecia)
Male pattern baldness is inherited (the exact mode is unclear) and androgen dependent. Over several cycles, the androgen-sensitive follicles miniaturize from terminal to vellus hairs. Males are affected from the second decade and, by the seventh decade, 80% have involvement. Patterned balding also occurs in females, the majority of whom are hormonally normal. It becomes more pronounced after the menopause and is present in 70% of 80-year-old women. In men, bitemporal recession followed by a bald crown is the usual pattern (Fig. 1); women may show this but more commonly exhibit a diffuse thinning. Mostly, no treatment is required but, if indicated, topical minoxidil (Regaine) produces some response in a third of cases, and finasteride can help.
