Hair and nail disorders
Alopecia is defined as hair loss; it is classified into diffuse and localised, scarring and non-scarring.
The growth of hair from follicles passes through a cycle (see Fig. 9.1). Causes of alopecia are given in Table 9.5.
Androgenic alopecia has a genetic tendency and is androgendependent. Males are affected more than females, starting from late teens increasing in incidence throughout life. In males the hairline recedes initially in the temporal regions before hair loss at the crown. In women there is more diffuse thinning of the hair. Topical minoxidil produces some response in up to 30% of cases. Finasteride is also used in androgenic alopecia in males.
Telogen effluvium occurs when the normally asynchronous cycles in follicles synchronises after childbirth, surgery or severe illness. The hair loss typically occurs 3 months after the precipitating event. It is self-limiting.
Alopecia areata is associated with autoimmune conditions in which anagen is prematurely arrested. Patients develop well-demarcated circular patches of hair loss, which may coalesce causing alopecia totalis. Pathognomonic is the presence of exclamation mark hairs, narrower at the scalp. Alopecia areata is refractory to treatment.
Metabolic disorders may present with hair loss: hypo/hyperthyroidism, hypopituitarism or hypoadrenalism, iron deficiency and malnutrition.