ABSTRACT
Telogen effluvium (TE) is a common cause of non-scarring hair loss and affects adult and pediatric patients of all ethnic and socioeconomic backgrounds. TE is characterized by increased shedding of scalp hair resulting in diffuse thinning, and can be clinically classified as acute (ATE, <6 months) or chronic (CTE, >6 months). The forms exist on a continuum, and acute TE may become chronic if inciting factor(s) are persistent (Figure 11.1). The pathogenesis of TE is the premature conversion of hair
follicles from the anagen phase to the telogen phase of the hair cycle. When this occurs, the affected follicles are committed to proceed to the exogen phase, during which loss occurs (Figure 11.2). The shift occurs at the level of the dermal papillae. TE is more accurately considered a medical sign related to
underlying conditions, rather than a discrete disorder (Figure 11.3). ATE often has a single cause, while CTE is more likely to be multifactorial. Triggers include acute physical stressors such as surgery, illness, orweight loss, hormones, psychological distress, physiologic events such as postpartum TE, drugs, nutritional deficiency, and scalp inflammation (Table 11.1). In some patients, TE “unmasks” other causes of hair loss such as senescent thinning, androgenetic alopecia, autoimmune disease, or nutritional deficiency, which may complicate the clinical picture. Onset of ATE may occur within 2 weeks of a trigger and peaks
after 6 to 8 weeks. When trigger(s) are identified and addressed, TE typically remits, and the patient experiences diminished shedding over 6 to 8 weeks. Regrowth of hair is appreciated after 4 to 6 months and optimized at 12 months. Some patients are subjected to multiple concomitant or sequential triggers, which prolong the course of TE.
