What is the next step to determine the diagnosis of hair loss?

Next Step: Clinical Pattern Recognition Through Scalp Examination

The next step is to perform a focused scalp examination to determine whether the hair loss is scarring versus non-scarring and to identify the specific pattern (patchy, diffuse, or localized), as this fundamentally directs all subsequent diagnostic decisions. 1, 2

Immediate Physical Examination Priorities

Determine Scarring Status

• Examine the scalp for follicular ostia (hair follicle openings) – their absence indicates scarring alopecia, which requires urgent evaluation and different management 2
• Look for inflammation, scaling, erythema, or pustules that suggest infectious or inflammatory scarring processes 1, 2

Identify Diagnostic Hair Findings

• Search for exclamation mark hairs (short broken hairs with tapered bases) around patches – these indicate active alopecia areata 1, 2
• Assess if hair pulls out easily with gentle traction – suggests active disease process 1
• Look for incomplete patches with firmly anchored broken hairs – this pattern suggests trichotillomania rather than alopecia areata 2

Pattern Classification

• Patchy loss: Consider alopecia areata, tinea capitis, trichotillomania, or early scarring alopecia 1, 3
• Diffuse loss: Androgenetic alopecia is most common, but also consider telogen effluvium, anagen effluvium, or diffuse alopecia areata 3, 2
• Localized/marginal: Traction alopecia or ophiasis pattern (worse prognosis in alopecia areata) 3

Dermoscopy/Trichoscopy

Dermoscopy should be performed as a non-invasive diagnostic tool that provides immediate diagnostic information 3, 4, 5:

• Yellow dots, exclamation mark hairs, and cadaverized hairs support alopecia areata 3
• This can yield faster and more accurate diagnosis than clinical examination alone 4

When Laboratory Testing Is Indicated

The British Journal of Dermatology emphasizes that investigations are unnecessary in most cases when the diagnosis is clinically evident 3, 2. However, order targeted testing when:

Uncertain or Atypical Presentations

• Fungal culture when tinea capitis is suspected (scalp scaling, inflammation, broken hairs) 1, 3
• Skin biopsy for difficult cases, suspected early scarring alopecia, or diffuse alopecia areata that is diagnostically challenging 1, 3
• Syphilis serology when secondary syphilis is suspected (moth-eaten pattern) 1, 3
• Lupus serology when systemic lupus erythematosus is in the differential (joint pain, photosensitivity, systemic symptoms) 1, 3

Diffuse Hair Loss Requiring Systemic Workup

• TSH to exclude thyroid disease (most important initial test) 3, 2
• Serum ferritin – iron deficiency is the most common nutritional deficiency causing chronic diffuse telogen hair loss 3
• Vitamin D level – 70% of alopecia areata patients are deficient (<20 ng/mL) versus 25% of controls, with inverse correlation to disease severity 3
• Serum zinc – tends to be lower in alopecia areata patients, particularly those with resistant disease >6 months 3

Women with Signs of Androgen Excess

When acne, hirsutism, or irregular periods are present 3:

• Total or free testosterone and SHBG
• Consider PCOS evaluation
• Prolactin if hyperprolactinemia suspected
• 2-hour glucose tolerance test if insulin resistance suspected

Critical Pitfalls to Avoid

• Do not order extensive laboratory panels when clinical diagnosis is evident – this wastes resources and delays appropriate management 3, 2
• Do not overlook dermoscopy – it provides valuable diagnostic information non-invasively 3
• Do not confuse trichotillomania with alopecia areata – broken hairs in trichotillomania remain firmly anchored in anagen phase, unlike exclamation mark hairs 2
• Do not miss scarring alopecia – these require urgent intervention to prevent permanent hair loss 2, 5