Chapter 86: Telogen Effluvium

AT-A-GLANCE

INTRODUCTION

Telogen effluvium (TE) was originally described by Kligman in 1961.¹ TE is best characterized by a premature termination of the anagen (growing) phase of hair follicles, with a resultant increase in telogen (resting) phase hairs leading to excessive and diffuse loss of club hairs.¹ Classically, TE refers to an acute hair loss subsequent to a variety of stresses including those caused by febrile diseases, childbirth, emotional disturbance, chronic systemic diseases, or the administration of heparin.¹ TE can be a physiologic event in the newborn.¹ Later studies revealed that the trigger and manifestation of TE were variable.^2,3 TE represents the most common cause of diffuse hair loss.³ In clinics, truly diffuse hair loss is not often encountered.⁴ The most common reason bringing TE patients to the clinic is the increase in hair shedding after shampooing or brushing alone.⁴ Typically, TE is self-limiting, and full recovery can be expected once the specific causes are identified and corrected.^3,4 However, especially in nonclassical chronic TE in women, distinction between female pattern hair loss is often challenging.⁵ In this chapter, the clinical features, pathophysiology, and differential diagnoses of TE are discussed.

EPIDEMIOLOGY

Approximately, the loss of more than 25% of scalp hairs has been reported to be necessary to clinically detect diffuse hair loss.¹ Therefore, most TE cases are likely to be subclinical, making estimation of its real incidence or prevalence quite difficult.^2,4 Female predominance has been noted in TE, probably because of stronger awareness of daily hair conditions and more dynamic hormonal changes including menstruation and gestation.^4,6 In theory, incidence of classic acute TE following known triggering events would not be distinct between the sexes.⁴ TE can occur in children but the incidence has been reported to be low.⁷ Elderly women are more likely to suffer from classic acute TE.⁴ Chronic TE (CTE) represents a unique form of unknown etiology that affects the whole scalp and is mostly seen in middle-aged women.^8,9

CLINICAL FEATURES

Depending on the clinical course and symptoms, TE can be subdivided into 3 subgroups: classic acute TE,¹ chronic diffuse telogen hair loss,^2,4,10 and chronic telogen effluvium^8,9 (Table 86-1). Irrespective of clinical subtypes, the most representative manifestation of TE is diffuse excessive shedding of club hairs.^1,2...