What is Telogen Effluvium?
Telogen effluvium (TE) is a common form of diffuse, non-scarring hair loss caused by an increased proportion of hair follicles prematurely entering the telogen (resting) phase, resulting in excessive shedding of normal club hairs typically 2-3 months after a triggering stressor. 1, 2
Pathophysiology
TE represents a disruption of the normal hair cycle where physiological or psychological stress causes hair follicles to prematurely terminate the anagen (growth) phase and shift into telogen 3. The condition manifests as increased loss of telogen club hairs, though the exact mechanisms through which stress influences the human hair cycle remain incompletely understood 4.
Five distinct functional mechanisms have been proposed 5:
- Immediate anagen release - abrupt termination of growth phase
- Delayed anagen release - gradual shortening of growth phase
- Short anagen syndrome - constitutionally shortened growth phase
- Immediate telogen release - premature shedding of resting hairs
- Delayed telogen release - prolonged retention followed by synchronized shedding
Recent evidence suggests that anagen shortening precedes follicular miniaturization, establishing TE as a potential precursor to androgenetic alopecia in men 6. This challenges traditional thinking about the relationship between these conditions.
Common Triggers
TE is multifactorial with numerous precipitants 1:
- Medical/surgical stressors - childbirth, prolonged surgery, severe febrile illness
- Rapid weight loss - mean threshold approximately 15% body weight loss at 3.54 kg/month 7
- Medications - chemotherapy and various other drugs
- Nutritional deficiencies - though less common than traditionally believed 8
- Endocrine disorders - thyroid dysfunction
- Psychological stress - though the bidirectional relationship between stress and hair loss creates diagnostic complexity 9
Clinical Presentation
The hallmark is diffuse hair shedding across the entire scalp rather than patterned loss 10, 4. Patients typically present with significant anxiety about sudden excessive hair loss, which substantially impacts quality of life even though the condition is generally self-limited 10, 9.
Critical timing: Hair loss becomes clinically apparent 2-3 months after the triggering event, reflecting the normal telogen duration before shedding occurs.
Diagnostic Approach
Diagnosis requires three key elements:
- Hair pull test - positive with easy extraction of telogen hairs
- Dermoscopic examination - to exclude other causes of diffuse hair loss
- Detailed history - to identify temporal relationship with known triggers occurring 2-3 months prior 10
Important caveat: The diagnosis is based on an increased telogen:anagen ratio, NOT on patient-reported quantity of shedding 6. In men with short hair, TE may go completely unnoticed despite being present.
Laboratory Evaluation
Contrary to popular belief, nutritional deficiencies are not as common as traditionally thought in TE patients 8. However, when investigating persistent cases, consider:
- Zinc levels (significantly lower in chronic TE) 8
- Ferritin and hemoglobin
- Thyroid function tests
- Vitamin B12 and vitamin D
- Copper/zinc ratio (elevated in TE) 8
Do not routinely order comprehensive nutritional panels - instead, use targeted testing based on specific clinical suspicion from the history 8.
Prognosis and Impact
TE is generally self-limited with high remission rates 4. However, the psychological impact is substantial - patients with TE demonstrate significantly higher scores for depression, anxiety, perceived stress, and reduced quality of life compared to controls 9. These psychological effects correlate directly with the degree of quality of life impairment.
Treatment Considerations
Minoxidil (topical or low-dose oral) is the primary treatment for TE 2. The medication works by:
- Prolonging anagen phase
- Promoting telogen-to-anagen transition
- Transforming vellus hairs to terminal hairs
For diffuse scalp involvement, low-dose oral minoxidil is preferred over topical formulations due to ease of use and patient compliance 2.
Key Clinical Pitfalls
- Do not dismiss TE as a "waste basket diagnosis" - it requires proper confirmation through hair pull testing and dermoscopy 11
- Failure to observe shedding does not negate TE diagnosis - particularly in men with short hair 6
- Do not assume nutritional deficiency without evidence - create individualized treatment plans based on identified triggers rather than empiric supplementation 8
- Recognize the bidirectional stress-hair loss relationship - address both the physical trigger and psychological impact 9