Influence of skin type, race, sex, and anatomic location on epidermal barrier function.

The intact skin represents a barrier to the uncontrolled loss of water, proteins, and plasma components from the organism. Owing to its complex structure, the epidermal barrier with its major layer, the stratum corneum, is the rate-limiting unit for the penetration of exogenous substances through the skin. The epidermal barrier is not a static structure. The status of different functions of the epidermis can be monitored by assessing specific biophysical parameters such as transepidermal water loss, stratum corneum hydration, and skin surface pH. Variables originating from the individual as well as exogenous factors have an important influence on the epidermal barrier parameters.