The evaluation of alopecia areata or hair loss begins with a history and physical examination. The diagnosis of alopecia areata is made on physical examination. Determining the exact cause usually requires blood tests or a biopsy.

Physical findings in those with alopecia areata include:

• Hair loss

Tests may identify an underlying cause.

Tests used to evaluate alopecia areata may include:

• Antinuclear antibodies
• Complete blood count
• DHEA blood level
• Free testosterone level
• T and B cell lymphocyte counts
• Thyroid profile
• Syphilis test

Other testing used to evaluate alopecia areata may include:

• Hair pull test
• Microscopic examination of the hair follicle
• KOH preparation:
• To look for fungus of the scalp
• Scalp biopsy