Female pattern hair loss is the most common type of alopecia in women. The prevalence of this condition increases with age, affecting almost 40% of women over the age of 70. Female pattern hair loss is a type of diffuse, nonscarring alopecia, characterized by shortening of the hair growth phase, follicular miniaturization, and conversion of thicker terminal hairs to shorter and finer vellus hairs. Patients typically report a gradual and progressive hair loss, localized to the bitemporal areas and the central scalp.
On examination, patients with female pattern hair loss appear to have a normal scalp, without evidence of inflammation or scarring; follicular orifices are present. Hair loss occurs in a typical pattern, with widening of the central part, thinning at the crown, and sparing of the frontal hairline. The "hair-pull test" may be used to differentiate female pattern hair loss from other types of diffuse, nonscarring alopecia. During this test, the clinician firmly grasps 40–60 hairs at their base and gently pulls away from the scalp. A positive test result occurs when more than three hairs are removed with each pull at different scalp locations, and is suggestive of alternative diagnoses, such as telogen or anagen effluvium or alopecia areata.
There are no specific laboratory abnormalities associated with female pattern hair loss; the majority of women will have normal serum testosterone levels. However, clinicians should perform testosterone, dehydroepiandrosterone sulfate (DHEAS), and prolactin testing in any patient presenting with female pattern hair loss and other signs of hyperandrogenism, such as hirsutism, virilization, or severe acne. Diffuse hair loss may also be seen in patients with low iron levels, nutritional deficiencies, and thyroid disease; testing for these abnormalities may be appropriate in certain individuals.
The goals of treatment are to slow hair loss and to stimulate new hair growth. Topical minoxidil is currently the only medication that is FDA approved for the treatment of female pattern hair loss. Twice-daily application of topical minoxidil 2% solution increases hair growth and is well-tolerated. Noticeable improvement may require at least 6–12 months of therapy, and hair loss will resume if the medication is stopped. Treatment should be avoided during pregnancy and lactation. Side effects of minoxidil include facial hypertrichosis and dermatitis. Although finasteride, a 5-alpha–reductase inhibitor, is effective for the treatment of male pattern hair loss, there are few data to support its use in female pattern hair loss. The results of a systematic review demonstrated that low-level light therapy increases total hair count; it may be used as adjunctive treatment. Data are limited regarding the efficacy and safety of spironolactone, dutasteride, and cyproterone acetate, and these agents should not be used as first-line therapies.
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