What is the workup for a patient presenting with diffuse hair loss?

Diagnostic Workup for Diffuse Hair Loss

The most effective diagnostic approach for diffuse hair loss requires a thorough clinical examination including dermoscopy, targeted laboratory testing based on clinical suspicion, and scalp biopsy when diagnosis remains uncertain after initial evaluation. 1

Initial Clinical Assessment

Physical Examination

• Assess hair distribution pattern and perform pull test to evaluate hair fragility
• Look for specific features using dermoscopy:
  • Yellow dots (alopecia areata)
  • Exclamation mark hairs
  • Hair shaft abnormalities
  • Signs of inflammation or scarring
  • Miniaturized hairs (androgenetic alopecia)
  • Cadaverized hairs

Differential Diagnosis

Four main diagnostic possibilities for diffuse nonscarring hair loss 2:

1. Female/male pattern hair loss (androgenetic alopecia)
2. Telogen effluvium (acute and chronic)
3. Diffuse alopecia areata
4. Anagen effluvium (drug-induced)

Common pitfalls in diagnosis include 3, 1:

• Misdiagnosing trichotillomania as alopecia areata
• Overlooking subtle tinea capitis
• Failing to recognize early scarring alopecia
• Not considering systemic causes of hair loss

Laboratory Testing

Laboratory tests should be targeted based on clinical suspicion 1:

• Complete blood count
• Ferritin levels (iron deficiency is a common cause of telogen effluvium) 4
• Thyroid stimulating hormone
• Vitamin D 25OH
• Additional tests when clinically indicated:
  • Androgen levels (DHEAS, testosterone, free testosterone)
  • Antinuclear antibody (for lupus)
  • Fungal culture (for suspected tinea capitis)

Advanced Diagnostic Techniques

• Dermoscopy/Trichoscopy: Critical non-invasive diagnostic tool with high accuracy 1
• Hair measurements:
  • Hair density
  • Hair diameter
  • Terminal-to-vellus hair ratio
• Scalp biopsy: Indicated for 3, 1:
  • Uncertain diagnosis after initial evaluation
  • Suspected scarring alopecia
  • Unusual presentations
  • Treatment-resistant cases

Diagnostic Algorithm

1. First-line assessment:

   • Clinical examination with dermoscopy
   • Hair pull test
   • Review of medical history, medications, and stressors 5

2. Laboratory testing based on clinical suspicion:

   • Iron studies (ferritin, CBC)
   • Thyroid function
   • Consider hormonal evaluation if pattern suggests androgenetic alopecia

3. Advanced diagnostics when diagnosis remains unclear:

   • Scalp biopsy
   • Specialized hair measurements

4. Consider specific conditions:

   • Telogen effluvium: Often triggered by physiologic/emotional stress, nutritional deficiencies, or endocrine imbalances 5
   • Androgenetic alopecia: Typically shows miniaturization pattern
   • Alopecia areata: May present as diffuse form that can be difficult to diagnose 3
   • Systemic disorders: Evaluate for underlying medical conditions 6

The diagnostic process should be methodical and comprehensive, as diffuse hair loss is frequently multifactorial 4. Early and accurate diagnosis allows for timely institution of appropriate treatment, which is crucial for patient outcomes and psychological well-being 7.