What are the key differences in diagnosis and treatment between acute and chronic telogen effluvium (excessive hair shedding) in patients?

Acute vs Chronic Telogen Effluvium: Key Differences

Acute telogen effluvium (ATE) is a self-limited condition lasting less than 6 months with spontaneous resolution in 80% of cases, while chronic telogen effluvium (CTE) persists beyond 6 months and requires active treatment with oral minoxidil showing the strongest evidence for reducing hair shedding. 1, 2

Diagnostic Distinctions

Acute Telogen Effluvium

• Duration: Less than 6 months from onset 3, 2
• Onset: Abrupt hair shedding typically 2-3 months after a triggering event 3
• Pattern: Diffuse shedding across entire scalp without visible hair loss or miniaturization on biopsy 1
• Triggering factors: Severe diet, iron deficiency, thyroid dysfunction, drugs, trauma, physiological stress, or postpartum state 3, 4
• Prognosis: Spontaneous remission in 80% of cases once trigger is eliminated 5, 6

Chronic Telogen Effluvium

• Duration: Persistent shedding for more than 6 months, often fluctuating for years 1, 2
• Onset: May begin abruptly but continues despite removal of initial trigger 2
• Pattern: Diffuse shedding without visible mid-frontal scalp hair loss (Sinclair stage 1) and no follicle miniaturization on biopsy 1
• Demographics: Predominantly affects women aged 30-60 years who had full hair prior to onset 2
• Associated conditions: May be primary or secondary to female pattern hair loss (FPHL), requiring careful distinction 1, 4

Critical Diagnostic Workup

First-Line Laboratory Testing (Both Types)

• Serum ferritin: Target >60 ng/mL; supplement if deficient with reassessment at 3 months 7, 6
• TSH: Screen for thyroid dysfunction; if abnormal, add free T4 and anti-TPO antibodies 7, 6
• Vitamin D level: Supplement if <20 ng/mL 7
• Serum zinc level: Supplement when deficient 7
• Complete blood count: Rule out systemic causes 7

Additional Testing When Indicated

• Hormonal workup: If signs of androgen excess (hirsutism, severe acne, irregular periods) are present, obtain total/free testosterone, SHBG, and screen for polycystic ovary syndrome 7, 6
• Scalp biopsy: Only if diagnosis uncertain or to exclude early scarring alopecia or diffuse alopecia areata 8, 7
• Hair wash test: Quantifies shedding; >100 hairs suggests active telogen effluvium 3, 9

Treatment Algorithms

Acute Telogen Effluvium Management

Step 1: Identify and eliminate the triggering factor 7, 5

• This is the cornerstone of treatment since 80% resolve spontaneously once the cause is removed 5, 6

Step 2: Correct nutritional deficiencies 7, 5

• Iron supplementation for ferritin <60 ng/mL 7
• Vitamin D supplementation for levels <20 ng/mL 7
• Zinc supplementation when deficient 7

Step 3: Consider topical minoxidil 5% for psychological reassurance 9

• Apply 1 mL twice daily to entire scalp 9
• Increases terminal hair count by 12.55 hairs/cm² at 4 weeks 9
• Nearly 70% show improvement (>100 shed hair decrease) 9
• Note: This is off-label use but may help patients feel reassured during the 3-6 month natural recovery period 9

Step 4: Provide psychological support and reassurance 7, 2

• Explain that shedding does not lead to complete baldness 2
• Set expectation for 3-6 month recovery timeline 3, 9

Chronic Telogen Effluvium Management

Step 1: Rule out concurrent female pattern hair loss 1, 4

• Perform scalp biopsy to confirm absence of follicle miniaturization 1
• Triggering causes with higher risk of concurrent FPHL include severe diet, iron deficiency, and thyroid dysfunction 4

Step 2: Initiate oral minoxidil as first-line treatment 1

• Dosing: Start with 0.25-2.5 mg once daily 1
• Efficacy: Reduces hair shedding score by 1.7 points at 6 months and 2.58 points at 12 months (p<0.001) 1
• Trichodynia benefit: Resolves scalp pain within 3 months in patients with this symptom 1

Step 3: Monitor for side effects 1

• Facial hypertrichosis occurs in 36% (13/36 patients); mild in most cases 1
• Transient postural dizziness in 2 patients, resolved with continued treatment 1
• Ankle edema rare (1 patient) 1
• Blood pressure changes minimal (mean -0.5 mmHg systolic, +2.1 mmHg diastolic) 1

Step 4: Continue treatment for at least 12 months 1

• All 36 patients in the highest quality study completed 12 months of treatment 1
• Condition is self-limiting in the long run but requires patience 2

Common Pitfalls to Avoid

• Failing to distinguish CTE from FPHL: Always perform scalp biopsy in CTE lasting >6 months to exclude miniaturization, as treatment differs significantly 1, 4
• Over-reassurance in CTE: Unlike ATE, CTE does not resolve spontaneously in 3-6 months and requires active treatment 1, 2
• Inadequate iron repletion: Target ferritin >60 ng/mL, not just "normal range" 7
• Missing the psychological impact: Hair shedding causes severe psychological stress; address this proactively with reassurance and early intervention 7, 2, 9
• Assuming all oral treatments are equal: Only oral minoxidil has demonstrated efficacy in CTE; other oral supplements (beyond correcting deficiencies) show no correlation with preventing progression to CTE 1, 4
• Delaying minoxidil in ATE-FAA association: When ATE is triggered by severe diet, iron deficiency, or thyroid dysfunction, there is higher risk of concurrent FPHL; minoxidil use shows a trend toward lower progression to CTE 4