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Chapter 9: Hair and nail disorders 397

Anagen,
Growth phase
lasts two to three years.

Catagen,
Release of hair shaft involutional phase
lasts two to three weeks

Telogen,
resting phase,
lasts three to four months
Figure 9.1 Normal hair growth.

crown. In women there is more diffuse thinning of the Table 9.6 Causes of hirsutism
hair. Topical minoxidil produces some response in up
Idiopathic Possible steroidogenic abnormality
to 30% of cases. Finasteride is also used in androgenic Iatrogenic Danzol, some oral contraceptive pills
alopecia in males. Pituitary Hyperprolacinaemia
Telogen effluvium occurs when the normally asyn-
Adrenal Congenital adrenal hyperplasia, Cushing’s
chronous cycles in follicles synchronises after child- syndrome
Ovarian Polycystic ovaries, hyperthecosis, some tumours
birth, surgery or severe illness. The hair loss typically
occurs 3 months after the precipitating event. It is self-
limiting.
Aetiology/pathophysiology
Alopecia areata is associated with autoimmune condi-

There is a wide geographical variation in the ‘normal’
tionsinwhichanagenisprematurelyarrested.Patients
body hair independent of androgen production. Hir-
develop well-demarcated circular patches of hair loss,
sutism is caused by increased androgen production or,
which may coalesce causing alopecia totalis. Pathog-
more rarely, increased sensitivity of hair follicles to an-
nomonic is the presence of exclamation mark hairs,
drogens (see Table 9.6). There may be associated men-
narrower at the scalp. Alopecia areata is refractory to
strual problems.
treatment.
Metabolic disorders may present with hair loss:

Clinical features
hypo/hyperthyroidism, hypopituitarism or hypoad-
Patientspresentwithmalepatternhairgrowthonthelip,
renalism, iron deficiency and malnutrition.
chin,chest,abdomen,back,armsandlegsmorethanthat
expected for a woman of the same ethnic background.
Women with a normal menstrual cycle are unlikely to
Hirsutism
have an endocrine cause. Other features may include
Definition acne, seborrhoea, androgenic alopecia, deepening of the
Hirsutism is the androgen-dependent growth of hair in voice and clitoromegaly. The abdomen should be exam-
awoman, which is in the same distribution as in males. ined for masses.