By Gary M. White, MD
This picture shows significant alopecia. Most of the time however, the loss is not so obvious. The patient's history should be trusted.
Diffuse hair loss commonly occurs in a young woman. The most common causes are low iron and telogen effluvium.
This page discusses the clinical situation of a young to middle-aged woman with diffuse hair thinning/loss. There are no individual bald spots (e.g., as in alopecia areata). The onset may be gradual over weeks to months or even years. The loss is usually across the top, sides, and front. Often, the back of the scalp is relatively spared. The skin of the scalp is normal.
Some cases may require biopsy for diagnosis. A 4 mm punch is preferred. The punch should be oriented at the same angle as the emerging hairs to avoid transecting hair follicles. More than one punch biopsy may be necessary allowing for both horizontal and transverse sectioning. Biopsying the advancing edge is less likely to be helpful than biopsying a more established area. The area chosen should be of several months duration and still active. If not diagnostic, a central scarred area may be biopsied. Evaluation with elastic tissue stains and polarized microscopy is particularly helpful here [JAAD 2016;74;p. 9].
The typical patient is a young to middle-aged woman who complains of hair thinning. Often, physical examination shows what appears to be a full head of hair, but the woman is certain this is abnormal for her. Usually, this is true. Whether the hair thinning is abnormal or a normal process of aging must be discerned. (Most people experience some thinning of hair as they age.) First, an examination should be done to exclude localized alopecia or scarring alopecia. Also, the hair should be falling out from the root, not breaking (as might occur if the hair has been damaged). Then, one should investigate, by history, if there are any acute stresses on the body that might trigger telogen effluvium in the three months leading up to onset (e.g., flu or other more severe illness, death in the family, pregnancy, car accident). Finally, the above labs may help exclude internal causes such as hypothyroidism, low iron, a hormonal abnormality and vitamin D deficiency. If the history and physical examination are unremarkable and the labs are normal, the diagnosis is female pattern hair loss (FPHL). Telogen effluvium (TE) may rarely become chronic and differentiation from FPHL may be difficult. The following may be helpful: The onset of FPHL usually is gradual whereas that of TE is more acute. Many miniaturized hairs are present in alopecia areata.