Evaluation and diagnosis of the hair loss patient: part I. History and clinical examination.

Hair loss (alopecia) is a common problem and is often a major source of distress for patients. The differential diagnosis of alopecia includes both scarring and nonscarring alopecias. In addition, many hair shaft disorders can produce hair shaft fragility, resulting in different patterns of alopecia. Therefore, an organized and systematic approach is needed to accurately address patients' complaints to achieve the correct diagnosis. Part 1 of this 2-part continuing medical education article on alopecia describes history taking and the clinical examination of different hair loss disorders. It also provides an algorithmic diagnostic approach based on the most recent knowledge about different types of alopecia.