What are the likely causes, appropriate workup, and treatment options for hair loss in a 16‑year‑old female?

Hair Loss in a 16-Year-Old Female

Most Likely Causes

In a 16-year-old female, the most common causes of hair loss are telogen effluvium (stress-induced shedding), alopecia areata (autoimmune patchy hair loss), and early androgenetic alopecia, with telogen effluvium being the most frequent in this age group. 1

Primary Differential Diagnoses

• Telogen effluvium presents as diffuse shedding across the entire scalp triggered by physiological stress, illness, rapid weight loss, emotional stress, or nutritional deficiencies, and typically begins 2-3 months after the inciting event 1, 2
• Alopecia areata appears as discrete round patches with "exclamation-mark" hairs (short broken hairs at patch margins) and is mediated by T-lymphocyte attack on hair follicles 3, 4
• Early androgenetic alopecia shows diffuse thinning over the central scalp with preserved frontal hairline, though this is less common in adolescence 5, 1
• Trichotillomania (compulsive hair pulling) presents with incomplete hair loss and firmly anchored broken hairs, distinguished from alopecia areata by the anagen-phase hair retention 3, 4
• Tinea capitis causes patchy loss with scalp inflammation and scaling, requiring fungal culture for diagnosis 3, 4

Clinical Examination Approach

Key Physical Findings to Assess

• Pattern of hair loss: Discrete patches indicate alopecia areata, while diffuse shedding suggests telogen effluvium or androgenetic alopecia 3
• Exclamation-mark hairs: Pathognomonic for alopecia areata when present at patch margins 3
• Scalp condition: Inflammation or scaling suggests tinea capitis or scarring alopecia rather than alopecia areata or telogen effluvium 3
• Hair pull test: More than 6 hairs easily extracted from different scalp areas indicates active shedding (positive in telogen effluvium and active alopecia areata) 6
• Dermoscopy findings: Yellow dots and exclamation-mark hairs confirm alopecia areata; their absence is characteristic of telogen effluvium 4

Essential History Elements

• Duration of hair loss: Onset less than 1 year suggests better prognosis, with 34-50% of alopecia areata cases achieving spontaneous remission within one year 3
• Precipitating events: Recent illness, surgery, emotional stress, rapid weight loss, or medication changes point toward telogen effluvium 1, 2
• Family history: Present in 20% of alopecia areata cases 3, 4
• Signs of androgen excess: Acne, hirsutism, or irregular periods suggest polycystic ovary syndrome and androgenetic alopecia 3, 1
• Hair-care practices: Tight hairstyles raise suspicion for traction alopecia 3

Laboratory Testing Strategy

Targeted laboratory testing is only indicated when the diagnosis is uncertain, the presentation is atypical, or systemic disease signs are present; routine extensive panels are unnecessary in straightforward cases. 7, 3

When to Order Laboratory Tests

• Fungal culture: Only if scalp inflammation or scaling suggests tinea capitis 7, 3
• Serum ferritin: Check if chronic diffuse hair loss is present; optimal level for hair growth is ≥60 ng/mL 3, 6
• TSH and free T4: Order if systemic symptoms suggest thyroid disease 3
• Vitamin D level: Consider testing, as 70% of alopecia areata patients are deficient versus 25% of controls 4, 6
• Serum zinc: May be lower in alopecia areata patients, particularly those with resistant disease >6 months 7, 4
• Total testosterone, free testosterone, and SHBG: Only if signs of androgen excess are present (acne, hirsutism, irregular periods) 3
• Scalp biopsy: Reserved for uncertain diagnosis or suspected scarring alopecia 7, 3

Tests to Avoid

• Extensive autoimmune panels are not recommended for straightforward alopecia areata, as the modest increase in autoimmune disease prevalence does not justify routine screening 7, 3

Treatment Algorithm

For Limited Patchy Alopecia Areata (≤5 patches, each ≤3 cm)

Watchful waiting with reassurance is the first-line approach, as 34-50% of patients experience spontaneous regrowth within one year without treatment. 7, 3

• Counsel that visible regrowth is unlikely within the first 3 months after a new patch appears 7, 3
• If treatment is desired, intralesional triamcinolone acetonide 5-10 mg/mL (0.05-0.1 mL per injection) administered monthly yields regrowth in approximately 62% of patients (Strength of recommendation B, Quality of evidence III) 3

For Extensive Alopecia Areata (>50% scalp involvement)

• Contact immunotherapy with diphenylcyclopropenone (DPCP) is the best-documented treatment but achieves response in less than 50% of appropriately selected patients and requires multiple clinic visits over several months (Strength of recommendation B, Quality of evidence II-ii) 3
• Wigs provide immediate cosmetic benefit and are often the most practical solution for extensive, longstanding disease 7, 3

For Telogen Effluvium

• Identify and remove the precipitating trigger (stress, nutritional deficiency, illness); spontaneous remission occurs in up to 80% of cases with short duration (<1 year) 7
• Reassure that this represents shedding rather than permanent hair loss and does not cause complete baldness 2

For Early Androgenetic Alopecia

• Topical minoxidil 2% solution applied twice daily is first-line therapy, though systematic data in adolescents are limited 3, 5
• This arrests progression rather than stimulates regrowth 3

For Tinea Capitis

• Systemic oral antifungal therapy is required; fungal culture must be obtained before initiating treatment 3, 4

Treatments to Avoid

• Potent topical corticosteroids lack convincing efficacy evidence for alopecia areata 7, 3
• Systemic corticosteroids and PUVA have potentially serious adverse effects and insufficient efficacy evidence 7, 3
• Oral zinc or isoprinosine are ineffective in controlled trials for alopecia areata 7

Critical Pitfalls to Avoid

• Do not confuse trichotillomania with alopecia areata: Trichotillomania shows broken hairs that remain firmly anchored in anagen phase, whereas alopecia areata displays exclamation-mark hairs 7, 3
• Do not order extensive laboratory panels when the diagnosis is clinically evident 7, 3
• Do not overlook the psychological impact: Hair loss can profoundly affect self-esteem, school performance, and social functioning in adolescents; referral to pediatric psychology is warranted when behavioral or emotional changes are noted 7, 3
• Do not promise cure: No current treatment alters the long-term natural history of alopecia areata, though some interventions may induce temporary regrowth 7, 3

When to Refer to Dermatology

• Diagnosis remains uncertain despite clinical and dermoscopic evaluation 3
• Extensive alopecia areata requiring contact immunotherapy 3
• Suspected scarring alopecia or treatment-resistant cases 3
• Scalp biopsy is warranted when the diagnosis cannot be clarified by non-invasive methods 3