What is telogen effluvium, including its causes, diagnostic work‑up, and management?

Telogen Effluvium: Definition, Causes, Diagnosis, and Management

What is Telogen Effluvium?

Telogen effluvium (TE) is a non-scarring diffuse hair loss disorder caused by an abnormal shift of hair follicles into the telogen (resting) phase, resulting in excessive shedding of normal club hairs typically 3-4 months after a triggering event. 1, 2

TE represents one of the most common presentations of diffuse alopecia and is generally self-limited, though it can significantly impact quality of life despite its high remission rate. 1, 3

Pathophysiology

The disorder results from perturbations in the hair cycle through five distinct mechanisms: 4

• Immediate anagen release – abrupt termination of the growth phase 4
• Delayed anagen release – prolonged growth phase followed by synchronized shedding 4
• Short anagen syndrome – constitutionally shortened growth phase 4
• Immediate telogen release – premature shedding of resting hairs 4
• Delayed telogen release – prolonged retention followed by mass shedding 4

Recent evidence suggests that anagen shortening precedes follicular miniaturization, establishing TE as a potential precursor to androgenetic alopecia in men. 5

Common Triggers and Causes

Physiological Stress

• Childbirth – the most classic trigger 3
• Sudden weight loss – occurs at approximately 15% body weight reduction or 3.5 kg/month loss rate 6
• Severe febrile illness 2
• Major surgery or prolonged anesthesia 2

Nutritional Factors

• Zinc deficiency – significantly lower levels found in chronic TE patients 7
• Iron deficiency – historically associated but not consistently demonstrated 7
• Vitamin B12, vitamin D, and biotin deficiencies show no consistent association in recent studies 7

Other Precipitants

• Medications – numerous drugs implicated 8, 4
• Psychological stress – considered the most commonly felt factor 1
• COVID-19 infection – emerging as a recognized trigger 1
• Endocrine disorders – thyroid dysfunction 2

Diagnostic Work-Up

Clinical Assessment

Look for these specific historical elements:

• Timing: Hair shedding beginning 3-4 months after a stressful event 2
• Pattern: Diffuse shedding across the entire scalp rather than focal loss 1
• Symptoms: Trichodynia (scalp pain/tenderness) may be present 8
• Quantification: Increased daily hair loss (normal is 50-100 hairs/day) 1

Physical Examination

• Hair pull test – positive when >6 hairs are extracted with gentle traction 8
• Hair wash test – quantifies shedding during shampooing 8

Dermoscopic Findings (Trichoscopy)

The diagnosis is supported by negative findings that exclude other alopecias: 9

• Absence of yellow dots – rules out alopecia areata 9
• Absence of exclamation-mark hairs – excludes autoimmune alopecia 9
• Absence of cadaverized (broken) hairs – differentiates from alopecia areata 9

Laboratory Investigations

Order these tests based on clinical suspicion:

• Zinc levels – most consistently associated with TE 7
• Copper/zinc ratio and selenium – significant predictors of chronic TE 7
• Complete blood count – assess for anemia 2
• Ferritin – though recent evidence questions its consistent association 7
• Thyroid function tests (TSH, free T4) – screen for thyroid disorders 2
• Vitamin B12 – if dietary deficiency suspected 2

Note: Routine supplementation with biotin, vitamin D, and other vitamins is not supported by evidence showing consistent deficiencies in TE patients. 7

Advanced Diagnostic Tools

• Trichogram – demonstrates increased telogen:anagen ratio (>20% telogen hairs is abnormal) 8
• Phototrichogram – tracks individual hair growth over time 8
• Scalp biopsy – reserved for unclear cases; shows increased telogen follicles without miniaturization 8

Management Approach

Primary Intervention

The essential first step is identifying and removing the causative trigger. 8 This alone often leads to resolution within 6-12 months as the hair cycle normalizes.

Pharmacological Options

Topical Minoxidil

• Standard treatment for accelerating recovery 8
• May cause initial shedding (paradoxical effect) 8

Oral Minoxidil

For patients requiring systemic therapy, oral minoxidil offers comparable efficacy to topical formulations with improved adherence: 10

• Women: Start 1.25 mg/day (range 0.625-5 mg/day) 10
• Men: Start 2.5 mg/day (range 1.25-5 mg/day) 10
• Common side effects: Hypertrichosis (24%), transient shedding (16-22%), mild edema (2%) 10
• Contraindications: Pericardial disease, uncontrolled hypertension, pregnancy 10

Corticosteroids

• May be used in select cases, though evidence is limited 8

Novel Treatments

• CNPDA formulation (caffeine, niacinamide, panthenol, dimethicone, acrylate polymer) shows promise 8

Targeted Supplementation

Only supplement based on documented deficiencies:

• Zinc supplementation – when serum levels are low 7
• Avoid empiric supplementation with biotin, vitamin D, or other vitamins without proven deficiency 7

Clinical Pitfalls

• Failure to recognize TE in men with short hair – shedding may go unnoticed despite being present 5
• Over-reliance on patient-reported shedding – diagnosis depends on increased telogen:anagen ratio, not subjective shedding reports 5
• Unnecessary supplementation – nutritional deficiencies are less common than traditionally thought 7
• Misdiagnosis as androgenetic alopecia – use trichoscopy to differentiate; TE lacks follicular miniaturization patterns 9
• Premature concern about treatment failure – natural resolution takes 6-12 months after trigger removal 3