What are the common causes and recommended evaluation for alopecia in female children?

Alopecia in Female Children: Common Causes and Evaluation

Most Common Causes

The four most common causes of alopecia in female children are tinea capitis (fungal infection), alopecia areata (autoimmune), traction alopecia/trichotillomania (trauma-related), and telogen effluvium (stress-induced shedding), accounting for 90-95% of all pediatric hair loss cases. 1, 2, 3

Tinea Capitis (Fungal Infection)

• Presents with patchy hair loss accompanied by scalp inflammation, scaling, and sometimes pustules 4
• Fungal culture is mandatory before initiating treatment, as incorrect diagnosis is the most common cause of treatment failure 4
• Requires systemic oral antifungal therapy; topical treatments alone are insufficient 4, 2

Alopecia Areata (Autoimmune)

• Accounts for approximately 26% of patchy hair loss cases in children 4
• Characterized by round, non-inflamed bald patches with peripheral "exclamation-mark hairs" (short broken hairs at patch margins) 4, 5
• Spontaneous regrowth occurs in 34-50% of children within one year without any treatment 4, 6, 5
• Approximately 20% have a family history of the condition 4, 6
• Associated with other autoimmune diseases (thyroid disease, vitiligo) and atopic conditions 4, 5

Traction Alopecia and Trichotillomania (Trauma-Related)

• Traction alopecia results from tight hairstyles (braids, ponytails, hair extensions) causing mechanical stress on hair follicles 6, 2
• Trichotillomania is compulsive hair pulling that shows incomplete hair loss with firmly anchored broken hairs remaining in anagen phase 4, 6
• Distinguished from alopecia areata by the pattern of broken hairs and hair distribution 4

Telogen Effluvium (Stress-Induced)

• Triggered by physiologic or emotional stressors: illness, surgery, severe emotional stress, rapid weight loss, or nutritional deficiencies 4, 2
• Presents as diffuse shedding over the entire scalp rather than patchy loss 6
• Usually self-limited once the triggering factor is removed 6, 2

Less Common but Important Causes

Nutritional Deficiencies

• Iron deficiency (low ferritin) is the most common nutritional cause worldwide and presents as chronic diffuse telogen hair loss 4
• Vitamin D deficiency (<20 ng/mL) shows strong association, with 70% of alopecia areata patients deficient versus 25% of controls 4
• Zinc deficiency impairs hair follicle function, with lower levels in alopecia areata patients 4

Androgenetic Alopecia

• Rare in prepubertal children but should be considered in adolescent females with signs of androgen excess (acne, hirsutism, irregular periods) 4, 6
• Presents as diffuse central scalp thinning with preserved frontal hairline 6

Congenital and Structural Abnormalities

• Loose anagen syndrome causes sparse-appearing hair due to hair-cycle anomalies 1
• Congenital lesions should be considered for localized alopecia present at birth 1

Recommended Diagnostic Evaluation

Clinical Examination

Dermoscopy is the single most useful non-invasive diagnostic tool to differentiate between causes 4, 6:

• Yellow dots and exclamation-mark hairs are pathognomonic for alopecia areata 4, 6
• Scalp inflammation or scaling suggests tinea capitis or scarring alopecia 6
• Pattern recognition: patchy versus diffuse, scarring versus non-scarring 7, 2

Laboratory Testing Algorithm

For clinically evident alopecia areata (patchy loss with exclamation-mark hairs), no routine laboratory testing is required 4, 6

Targeted testing is indicated only when:

1. Diagnosis is uncertain or presentation is atypical 4, 6

   • Fungal culture if inflammation or scaling present (to rule out tinea capitis) 4, 2
   • Scalp biopsy for suspected scarring alopecia or when dermoscopy is inconclusive 4, 6

2. Nutritional deficiencies are suspected 4:

   • Serum ferritin (optimal ≥60 ng/mL for hair growth)
   • Vitamin D level (deficiency <20 ng/mL)
   • Serum zinc level

3. Systemic disease features are present 4, 6:

   • TSH and free T4 if thyroid symptoms present
   • Lupus serology only if systemic features (joint pain, photosensitivity, facial rash) present
   • Syphilis serology only with relevant risk factors

4. Signs of androgen excess in adolescents 4, 6:

   • Total testosterone, free testosterone, SHBG
   • Consider evaluation for polycystic ovary syndrome

Common Diagnostic Pitfalls to Avoid

• Do not order extensive autoimmune panels for straightforward alopecia areata, as the modest increase in autoimmune disease prevalence does not justify routine screening 4, 6
• Do not confuse trichotillomania with alopecia areata: trichotillomania shows firmly anchored broken hairs in anagen, while alopecia areata displays exclamation-mark hairs 4, 6
• Do not rely on clinical appearance alone for tinea capitis; fungal culture is mandatory before treatment 4, 2
• Do not overlook the psychological impact of hair loss on children, which can affect self-esteem, school performance, and overall development; consider referral to pediatric psychology when behavioral or emotional changes are noted 4

When to Refer to Dermatology

• Diagnosis remains uncertain despite clinical and dermoscopic evaluation 6, 2
• Suspected or confirmed scarring alopecia 6, 2
• Extensive alopecia areata (>50% scalp involvement) requiring specialized treatment 6
• Treatment-resistant cases 2
• Need for scalp biopsy 6, 2