• 06 JUL 14
    • 0

    Androgenetic Alopecia

    Androgenetic (or pattern) alopecia is a genetically determined disorder characterized by the gradual conversion of terminal hairs into indeterminate, and finally into vellus, hairs. It is an extremely common disease that affects men and women.

    Signs and symptoms

    Signs of androgenetic alopecia include the following:

    • Gradual onset
    • Increased hair shedding
    • Transition in the involved areas from large, thick, pigmented terminal hairs to thinner, shorter, indeterminate hairs and finally to short, wispy, nonpigmented vellus hairs
    • End result can be an area of total denudation; this area varies from patient to patient and is usually most marked at the vertex

    Diffuse alopecia areata may mimic the androgenetic form. The presence of exclamation point hairs, pitted nails, or a history of periodic regrowth or tapered fractures noted on hair counts suggests the diagnosis of diffuse alopecia areata.

    Males

    • Men note a gradual recession of the frontal hairline early in the process
    • Men present with gradual thinning in the temporal areas, producing a reshaping of the anterior part of the hairline

    Females

    • Hair generally is lost diffusely over the crown; this produces a gradual thinning of the hair rather than an area of marked baldness; the part is widest anteriorly
    • The frontal hairline is often preserved in women
    • Bitemporal recession does occur in women but usually to a lesser degree than in men

    See Clinical Presentation for more detail.

    Diagnosis

    Laboratory studies

    History and the physical examination are the most important aspects of diagnosis in patients with androgenetic alopecia. The following laboratory tests, however, can play a role in patient assessment:

    • Dehydroepiandrosterone (DHEA)-sulfate and testosterone analysis: In women, if virilization is evident
    • Iron, total iron-binding capacity, and transferrin saturation: To test for iron deficiency, if telogen effluvium is present
    • Thyrotropin level: If a thyroid disorder is suspected

    Biopsy and histology

    A biopsy is rarely necessary to make the diagnosis of androgenetic alopecia. If a single biopsy specimen is obtained, it should generally be sectioned transversely if pattern alopecia is suspected.

    In androgenetic alopecia, hairs are miniaturized. Although the condition is considered a noninflammatory form of hair loss, a superficial, perifollicular, inflammatory infiltrate is noted at times. A mildly increased telogen-to-anagen ratio is often observed.

    See Workup for more detail.

    Management

    The following drugs have been approved by the FDA for the treatment of androgenetic alopecia:

    • Minoxidil: Androgen-independent hair-growth stimulator
    • Finasteride: 5-Alpha reductase type 2 inhibitor

    The cosmetic results of surgical treatment for androgenetic alopecia are often satisfactory. Micrografting produces a more natural appearance than does the old technique of transplanting plugs.

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