Alopecia
Alopecia is loss of hair that is either scarring (permanent) or nonscarring (potentially reversible); the most common nonscarring pattern encountered as a new, diffuse complaint is telogen effluvium, in which a physiologic or emotional stressor prematurely converts growing (anagen) follicles into the resting (telogen) phase, producing diffuse shedding roughly three months later. Diagnosis rests on history and examination of the shedding pattern, and management is to identify and correct the trigger while reassuring the patient that regrowth follows resolution of the underlying stressor.
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What this article covers
- Overview
Definition: alopecia is loss of hair from the scalp or body, classified along two axes, scarring versus nonscarring and localized versus generalized; scarring alopecia destroys the follicle and is…
- Epidemiology
Postpartum period: the childbirth-related trigger is a classically cited setting for telogen effluvium, reflecting the abrupt withdrawal of the pregnancy-associated prolongation of the anagen phase.
- Risk factors
Physiologic stressors: childbirth, significant weight loss, eating disorders, high fever, major surgery, and significant blood loss are recognized triggers.
- Pathophysiology
Normal cycle disrupted: scalp hairs normally cycle asynchronously through a long anagen (growth) phase, a brief catagen (transition) phase, and a short telogen (resting) phase, after which the resting hair is shed.
- Clinical features
Diffuse, not patchy, shedding: the hallmark is generalized thinning of scalp hair density rather than discrete, well-circumscribed bald patches, distinguishing it on inspection alone from alopecia areata.
- Differential diagnosis
Alopecia areata: unlike the diffuse shedding of telogen effluvium, alopecia areata produces well-circumscribed, round, smooth patches of nonscarring hair loss, often with pathognomonic "exclamation…
- Diagnosis
Clinical diagnosis, confirmed by pattern: telogen effluvium is diagnosed clinically from the combination of diffuse (not patchy) nonscarring shedding, a normal underlying scalp, and an identifiable…
- Management
First, identify and correct the underlying trigger: review recent illness, surgery, blood loss, weight change, medications, and emotional stress, and treat or remove whichever is identified.
- Complications
Diagnostic delay of the true trigger: because the hair loss itself is benign and self-limited, the greater risk is failing to identify and treat an underlying condition, such as unrecognized anemia…
- Prognosis
Favorable and self-limited: in most cases telogen effluvium resolves spontaneously, with resumption of normal hair growth once the inciting factor has resolved.
- Prevention
Screen for and correct anemia and thyroid disease as modifiable, directly implicated triggers before they progress to a chronic shedding pattern; iron replacement with ferrous sulfate 325 mg PO once…
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