Investigations for Significant Hair Loss
In most cases of hair loss, extensive laboratory investigations are unnecessary and the diagnosis can be made clinically. 1
Clinical Assessment First
The initial approach should focus on determining whether the hair loss is:
- Scarring vs. non-scarring alopecia - This fundamentally changes the diagnostic pathway 2
- Pattern of hair loss - Diffuse, patterned (androgenetic), or focal (patchy) 3
- Clinical features - Presence of exclamation mark hairs, scalp inflammation, broken hairs, or nail changes 1
When Investigations ARE Indicated
Laboratory testing should be reserved for specific clinical scenarios when the diagnosis is uncertain. 1
Targeted Testing Based on Clinical Suspicion:
- Fungal culture - When tinea capitis is suspected (scalp inflammation, broken hairs, especially in children) 1
- Skin biopsy - Essential for all scarring alopecias and when diagnosis remains unclear after clinical examination 1, 2, 4
- Serology for lupus erythematosus - If systemic lupus erythematosus is in the differential 1
- Serology for syphilis - When secondary syphilis is considered 1
Routine Laboratory Panel (When Systemic Disease Suspected):
According to recent evidence, the following tests may be considered when diffuse hair loss suggests underlying systemic disease: 4
Important Caveats
Routine screening for autoimmune diseases is NOT recommended even though alopecia areata has increased frequency of autoimmune associations, as this frequency is insufficient to justify routine testing. 1
Iron status testing is NOT routinely recommended. While one small case series suggested iron deficiency was more common in women with alopecia areata, two subsequent studies failed to confirm this, and no published studies demonstrate treatment response to iron replacement therapy. 1
Diagnostic Tools Beyond Laboratory Testing
Dermoscopy should be utilized as it aids diagnosis by identifying: 1
- Yellow dots (active alopecia areata)
- Exclamation mark hairs (alopecia areata)
- Comma-shaped or corkscrew hairs (tinea capitis)
- Black dot hair stubs
Scalp biopsy is strongly recommended for all cicatricial (scarring) alopecias and doubtful cases, as it can confirm diagnosis and guide treatment. 2
Common Pitfalls to Avoid
- Over-testing in alopecia areata - The diagnosis is usually straightforward clinically and investigations are unnecessary in most cases 1
- Missing tinea capitis - Always consider fungal culture in children or when scalp inflammation is present, even if subtle 1
- Delaying biopsy in scarring alopecia - Early diagnosis and treatment are critical for prognosis in cicatricial alopecias 2
- Assuming all hair loss needs extensive workup - Most non-scarring alopecias like telogen effluvium and androgenetic alopecia are diagnosed clinically 3, 2