What is the recommended diagnostic work‑up and first‑line treatment for alopecia (including androgenetic hair loss, alopecia areata, telogen effluvium, and scarring alopecia)?

Treatment of Alopecia: Diagnostic Work-Up and First-Line Management

Initial Diagnostic Approach

The diagnosis of alopecia begins by determining whether the hair loss is scarring or non-scarring through scalp examination, as this fundamentally directs all subsequent diagnostic and therapeutic decisions. 1

Key Clinical Features to Identify

• Alopecia areata presents with patchy hair loss, exclamation mark hairs (short broken hairs with tapered bases around expanding patches), and slightly reddened but otherwise normal-appearing scalp 2, 3
• Androgenetic alopecia shows diffuse thinning at the crown with frontal hairline preservation in women, and is the most common cause of diffuse hair loss 3, 4
• Telogen effluvium presents as diffuse shedding triggered by physiologic or emotional stressors (illness, surgery, childbirth, rapid weight loss) occurring 2-3 months after the triggering event 3
• Trichotillomania shows incomplete hair loss with firmly anchored broken hairs that remain in anagen phase, distinguishing it from alopecia areata 2, 1
• Tinea capitis demonstrates scalp inflammation and scaling, though signs may be subtle 2

Dermoscopy as Primary Diagnostic Tool

Dermoscopy is the single most useful non-invasive diagnostic tool to differentiate between diffuse alopecia areata, telogen effluvium, and androgenetic alopecia. 3, 5

• Yellow dots, exclamation mark hairs, and cadaverized hairs are pathognomonic for alopecia areata 3, 5
• Absence of these features is characteristic of telogen effluvium and androgenetic alopecia 3

Laboratory Testing Algorithm

Investigations are unnecessary in most cases of alopecia areata when the diagnosis is clinically evident. 2, 3

When to Order Laboratory Tests

Order targeted testing when:

• Diagnosis is uncertain or presentation is atypical 2, 3
• Diffuse hair loss without clear pattern 3, 5
• Signs suggesting systemic disease 2

Essential Laboratory Panel for Unclear Cases

• Serum ferritin: Iron deficiency is the most common nutritional deficiency worldwide and causes chronic diffuse telogen hair loss 3, 5
• Vitamin D level: 70% of alopecia areata patients have deficiency (<20 ng/mL) versus 25% of controls, with lower levels correlating inversely with disease severity 3, 5
• TSH: Rule out thyroid disease, which commonly causes hair loss 3, 5
• Zinc level: Tends to be lower in alopecia areata patients, particularly those with resistant disease >6 months 3, 5
• Fungal culture: Mandatory when tinea capitis is suspected 2, 3

Additional Tests for Specific Scenarios

• Serology for lupus erythematosus when systemic lupus is suspected 2, 3
• Serology for syphilis when secondary syphilis is in the differential 2, 3
• Skin biopsy for difficult cases, early scarring alopecia, or when diffuse alopecia areata diagnosis remains uncertain after dermoscopy 2, 3
• Total testosterone, free testosterone, and SHBG in women with signs of androgen excess (acne, hirsutism, irregular periods) 3

First-Line Treatment by Diagnosis

Alopecia Areata

Intralesional corticosteroid injections (triamcinolone acetonide 5-10 mg/mL) are first-line treatment for limited patchy alopecia areata, with the strongest evidence (Strength of recommendation B, Quality of evidence III). 2, 3, 5

Critical Counseling Points Before Treatment

• No treatment alters the long-term disease course; therapies only induce temporary regrowth 2, 1
• 34-50% of patients recover spontaneously within 1 year, though almost all experience recurrent episodes 2, 1
• 80% spontaneous remission occurs in patients with small circumscribed patches 2, 1
• Observation without treatment is legitimate for many patients given high spontaneous remission rates 1
• Relapse during or after initially successful treatment is common 1

Treatment by Disease Extent

• Limited patchy disease: Intralesional corticosteroids first-line 2, 3
• Extensive patchy disease: Contact immunotherapy is the best-documented treatment, though response rates are lower in severe cases 3, 5
• Poor prognosis indicators: Childhood onset, ophiasis pattern (scalp margin involvement), progression to alopecia totalis/universalis (full recovery unusual, <10%) 2, 3

Androgenetic Alopecia

For male androgenetic alopecia, oral finasteride and topical minoxidil solution have the best level of evidence for efficacy and safety. 6

For female androgenetic alopecia, topical minoxidil solution is the most effective and safe treatment. 6

• Oral minoxidil (0.625-2.5 mg daily) shows efficacy in both androgenetic alopecia and telogen effluvium, with 52.4% demonstrating clinical improvement and 42.9% stabilization 7
• Finasteride is approved for men only and should not be used in women of childbearing potential 6

Telogen Effluvium

No active treatment is recommended for telogen effluvium, as spontaneous remission occurs in up to 80% of patients with hair loss duration <1 year. 5

• Address underlying triggers (nutritional deficiencies, thyroid disease, medications) 3
• Reassurance and observation are appropriate first-line management 5

Nutritional Supplementation Strategy

• Vitamin D supplementation for levels <20 ng/mL according to general international recommendations for adults 3, 5
• Zinc supplementation may benefit patients with documented deficiency, particularly those with alopecia areata resistant >6 months 3, 5
• Iron supplementation for low ferritin levels 3

Common Pitfalls to Avoid

• Do not order extensive laboratory panels when clinical diagnosis is evident, as this wastes resources and delays appropriate management 3, 1
• Do not promise cure or disease modification for alopecia areata, as no treatment alters long-term disease course 2, 1
• Do not overlook the psychological burden: Assess mental health impact and provide counseling and psychological support, as patients commonly experience anxiety, depression, and reduced quality of life 3, 5, 1
• Do not confuse trichotillomania with alopecia areata: Broken hairs in trichotillomania remain firmly anchored in anagen phase, unlike exclamation mark hairs 2, 1
• Do not fail to obtain fungal culture before treating suspected tinea capitis, as incorrect diagnosis made on clinical grounds alone is the most common cause of treatment failure 3