What is the appropriate workup for alopecia?

Workup for Alopecia

In most cases of alopecia areata, investigations are unnecessary when the diagnosis is clinically evident; however, when the diagnosis is uncertain or the presentation is atypical, targeted laboratory testing and dermoscopy should guide your evaluation. 1

Clinical Examination First

Dermoscopy is the single most useful non-invasive diagnostic tool to differentiate between alopecia types and should be performed before ordering any laboratory tests. 2, 3

Key Dermoscopic Findings:

• Yellow dots, exclamation mark hairs, and cadaverized hairs are pathognomonic for alopecia areata 1, 2
• Exclamation mark hairs are short broken hairs with fractured tips found around expanding patches 1, 4
• Black dots indicate hairs fractured before emergence from the scalp 2
• A positive hair pull test at margins of expanding areas signals active disease 2

Pattern Recognition:

• Patchy hair loss with exclamation mark hairs confirms alopecia areata 1, 4
• Diffuse thinning at the crown with frontal hairline preservation indicates androgenetic alopecia 2, 4
• Scalp inflammation or scaling suggests tinea capitis or early scarring alopecia and requires fungal culture 2, 4

When Laboratory Testing IS Indicated

Laboratory tests should be ordered only when: 1, 2

• The diagnosis remains uncertain after dermoscopy
• Presentation is atypical or diffuse
• You need to exclude conditions in the differential diagnosis

Targeted Laboratory Tests:

For uncertain diagnosis or atypical presentation: 1, 2

• Fungal culture when tinea capitis is suspected (inflammation or scaling present) 1, 2, 4
• Skin biopsy for difficult cases, early scarring alopecia, or diffuse alopecia areata that is diagnostically challenging 1, 2
• Serology for lupus erythematosus when systemic features (joint pain, photosensitivity, facial rash) are present 1, 2
• Serology for syphilis when secondary syphilis is suspected based on risk factors 1, 2

For nutritional and endocrine evaluation (when diffuse hair loss without clear cause): 2, 3, 4

• Serum ferritin (optimal ≥60 ng/mL needed for hair growth; iron deficiency is the most common nutritional deficiency worldwide) 2, 4
• Vitamin D level (deficiency <20 ng/mL present in 70% of alopecia areata patients versus 25% of controls) 2, 3
• Serum zinc (tends to be lower in alopecia areata patients, particularly those with resistant disease >6 months) 2, 3
• TSH and free T4 to rule out thyroid disease, which commonly causes hair loss 2, 4
• Folate level may contribute to hair loss when deficient 2

For signs of androgen excess ONLY (acne, hirsutism, irregular periods): 2

• Total testosterone or bioavailable/free testosterone
• Sex hormone binding globulin (SHBG)
• Consider evaluation for polycystic ovary syndrome (PCOS)

Common Pitfalls to Avoid

• Do not order excessive laboratory tests when characteristic dermoscopic findings already confirm the diagnosis of alopecia areata 2, 4
• Do not routinely screen for autoimmune diseases in alopecia areata patients, as the increased frequency of autoimmune disease is insufficient to justify routine screening 1, 4
• Do not routinely test for iron status in alopecia areata, as studies have not confirmed increased iron deficiency and no published studies demonstrate treatment response to iron replacement 1
• Do not overlook the psychological impact of alopecia, which may warrant assessment for anxiety and depression 1, 2
• Do not mistake trichotillomania for alopecia areata: in trichotillomania, broken hairs remain firmly anchored in anagen phase, whereas alopecia areata shows exclamation mark hairs 2, 4

Differential Diagnosis to Consider

When evaluating alopecia, consider: 1, 2, 4

• Trichotillomania (compulsive hair pulling with incomplete hair loss)
• Tinea capitis (fungal infection with inflammation and scaling)
• Early scarring alopecia
• Telogen effluvium (stress-induced diffuse shedding)
• Anagen effluvium (drug-induced, particularly chemotherapy)
• Systemic lupus erythematosus
• Secondary syphilis
• Androgenetic alopecia (pattern hair loss)

Practical Clinical Algorithm

1. Perform dermoscopy first looking for yellow dots and exclamation mark hairs 2
2. If characteristic dermoscopic features present, diagnose alopecia areata clinically without biopsy or laboratory testing 1, 2
3. If dermoscopy inconclusive, obtain targeted laboratory tests to exclude telogen effluvium triggers and tinea capitis 2
4. If diagnosis remains uncertain, perform scalp biopsy for definitive histopathologic diagnosis 2

Prognostic Indicators

• Nail involvement (pitting, ridging, or dystrophy in ~10% of patients) predicts poorer prognosis 2, 4
• Natural history matters: 34-50% of alopecia areata patients recover within one year without treatment, making observation a reasonable option for limited disease 1, 2, 4
• Childhood onset and ophiasis pattern (scalp margin involvement) carry poorer prognoses 2