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

Initial Workup for Hair Loss

The initial workup for hair loss should begin with a focused clinical history and physical examination to determine the pattern of hair loss, followed by selective laboratory testing only when clinically indicated—most cases of alopecia areata require no laboratory workup at all. 1, 2

Clinical History

Document the following specific details:

• Onset, duration, and progression of hair loss to distinguish acute from chronic conditions 2, 3
• Family history of hair loss, present in approximately 20% of alopecia areata cases 1, 2
• Medication review for drugs causing anagen effluvium (chemotherapy, anticoagulants, beta-blockers) 1, 3
• Hair care practices that might cause traction alopecia 2, 3
• Systemic symptoms suggesting autoimmune disease (thyroid symptoms, lupus features) 2, 3
• Recent stressors including illness, surgery, childbirth, rapid weight loss, or emotional stress that could trigger telogen effluvium 1

Physical Examination

Examine for these specific findings:

• Scalp assessment for redness, inflammation, or scaling (tinea capitis) 2, 3
• Exclamation mark hairs (short broken hairs around expanding patches)—pathognomonic for alopecia areata 1, 2
• Hair pattern distribution: diffuse crown thinning with frontal preservation suggests androgenetic alopecia; patchy loss suggests alopecia areata 1
• Nail examination for pitting, ridging, or dystrophy (present in 10% of alopecia areata patients) 1, 2
• Lymphadenopathy, particularly occipital and cervical nodes 2, 3

Dermoscopy

Dermoscopy is a valuable non-invasive diagnostic tool that should not be overlooked:

• Yellow dots, exclamation mark hairs, and cadaverized hairs confirm alopecia areata 1, 2
• Regular round yellow dots indicate active disease progression 3

Laboratory Testing

Laboratory investigations are unnecessary in most cases of alopecia areata when the diagnosis is clinically evident. 1, 2 However, selective testing is indicated in specific scenarios:

When to Order Laboratory Tests:

• Uncertain or atypical presentations 1
• Diffuse alopecia that may represent telogen effluvium or diffuse alopecia areata 1
• Signs of androgen excess (acne, hirsutism, irregular periods) 1

Recommended Laboratory Panel (When Indicated):

• Serum ferritin: Lower in women with alopecia areata and androgenetic alopecia; iron deficiency is the most common nutritional deficiency causing chronic diffuse telogen hair loss 1
• Vitamin D (25-OH): 70% of alopecia areata patients have levels <20 ng/mL versus 25% of controls, with inverse correlation to disease severity 1
• Thyroid stimulating hormone (TSH): Rule out thyroid disease, a common cause of hair loss 1
• Zinc levels: Tend to be lower in alopecia areata patients, particularly those with resistant disease >6 months 1
• Total testosterone or free testosterone and SHBG: In women with signs of androgen excess 1
• Prolactin: If hyperprolactinemia suspected 1

Additional Diagnostic Procedures (When Indicated)

• Fungal culture: Mandatory when tinea capitis is suspected—the most common cause of treatment failure in onychomycosis is incorrect diagnosis made on clinical grounds alone 1, 3
• Skin biopsy: For difficult cases, early scarring alopecia, or diffuse alopecia areata that is challenging to diagnose 1, 3
• Serology for lupus or syphilis: When systemic lupus or secondary syphilis is in the differential diagnosis 1, 3

Common Pitfalls to Avoid

• Ordering excessive laboratory tests when the diagnosis is clinically evident—alopecia areata is typically diagnosed clinically 1, 2
• Misdiagnosing diffuse alopecia areata as telogen effluvium 2
• Overlooking tinea capitis with subtle inflammation 2
• Failing to recognize trichotillomania, distinguished by broken hairs remaining firmly anchored 1, 2
• Neglecting the psychological impact of alopecia areata, which may warrant assessment for anxiety and depression 1

Prognostic Indicators

• Patients with <25% hair loss initially have better outcomes, with 68% disease-free at follow-up 2
• Patients with >50% hair loss initially have poorer outcomes, with only 8% disease-free at follow-up 2
• Childhood onset and ophiasis pattern (scalp margin involvement) carry poorer prognoses 1
• Natural history: 34-50% of alopecia areata patients recover within one year without treatment 1, 3