How to diagnose hair loss.

This review presents a systematic approach to the diagnosis of hair loss. An accurate diagnosis is based on history, clinical examination, laboratory tests, and scalp biopsy. Whether the hair loss is a cicatricial or noncicatricial alopecia guides one's history taking. After assessing the patient's global appearance, the hair and scalp are evaluated, aided by a hair pull, hair tug, Hair Card, and hair mount. Scalp biopsies can confirm a diagnosis and are essential in all cases of cicatricial alopecia. In all patients with hair loss a complete blood count, ferritin, thyroid stimulating hormone, and vitamin D 25OH should be ordered.