How to evaluate for androgenetic (male/female pattern baldness) alopecia?

Evaluation of Androgenetic Alopecia

Androgenetic alopecia (AGA) evaluation should begin with trichoscopy to identify characteristic miniaturization patterns, followed by assessment of hair density, diameter variation, and distribution pattern to confirm diagnosis. 1

Initial Diagnostic Assessment

Clinical Examination

• Hair loss pattern assessment:
  • Males: Recession of frontotemporal hairline and/or vertex thinning
  • Females: Diffuse thinning over the crown with preservation of frontal hairline
• Trichoscopy findings (critical non-invasive diagnostic tool):
  • Hair shaft diameter variation (>20% variability)
  • Increased proportion of vellus hairs
  • Yellow dots
  • Decreased follicular units
  • Terminal-to-vellus hair ratio assessment

Additional Diagnostic Methods

1. Pull test: Assess active shedding (positive if >6 hairs extracted)
2. Hair counts: Count number of hairs in defined scalp areas
3. Photography: Document baseline appearance for comparison
4. Hair diameter measurements: Using micrometer or specialized tools

Laboratory Evaluation

Routine endocrinologic evaluation is not recommended for most patients with AGA 2. However, laboratory testing is indicated in specific situations:

For Women with Signs of Androgen Excess:

• Irregular menses
• Hirsutism
• Infertility
• Truncal obesity
• Clitoromegaly

Recommended Tests When Indicated:

• Free and total testosterone
• Dehydroepiandrosterone sulfate (DHEA-S)
• Androstenedione
• Luteinizing hormone
• Follicle-stimulating hormone
• Thyroid stimulating hormone
• Ferritin levels
• Vitamin D 25OH levels

When to Consider Polycystic Ovarian Syndrome (PCOS):

Diagnosis requires 2 of 3 criteria:

1. Androgen excess (clinical or biochemical)
2. Ovulatory dysfunction (oligo- or anovulation)
3. Polycystic ovaries (ultrasonographic findings)

Advanced Diagnostic Methods

Scalp Biopsy

• Indications: When diagnosis is uncertain or to rule out scarring alopecia
• Findings in AGA: Miniaturized follicles, increased telogen:anagen ratio

Trichogram

• Provides objective data on treatment response
• Measures hair density, diameter, and terminal:vellus ratio

Differential Diagnosis

Key conditions to distinguish from AGA:

• Telogen effluvium: Diffuse shedding without miniaturization
• Alopecia areata: Well-defined patches of complete hair loss with "exclamation mark" hairs
• Trichotillomania: Broken hairs that remain firmly anchored in anagen phase
• Tinea capitis: Scalp inflammation and scaling
• Scarring alopecia: Permanent follicular destruction

Monitoring Response to Treatment

• Regular follow-up every 3-6 months
• Document progress using standardized methods:
  • Repeat trichoscopy
  • Global photography
  • Hair counts in defined areas
  • Patient self-assessment questionnaires

Common Pitfalls to Avoid

1. Failing to distinguish between AGA and telogen effluvium, which can coexist
2. Not evaluating women for hormonal abnormalities when clinical signs of hyperandrogenism are present
3. Missing early signs of scarring alopecia, which requires different management
4. Inadequate baseline documentation, making treatment response difficult to assess
5. Overlooking psychological impact of hair loss on quality of life

By following this systematic approach to evaluation, clinicians can accurately diagnose androgenetic alopecia and establish appropriate treatment plans to improve outcomes related to morbidity and quality of life.