Cutaneous homeostasis and epidermal barrier function in a young healthy Caucasian population.

BACKGROUND Transepidermal water loss (TEWL), stratum corneum hydration (SCH), and skin surface pH are indicators of skin barrier integrity. There is scant evidence on normative data for cutaneous homeostasis parameters in healthy individuals. OBJECTIVES To develop normative data for skin erythema, melanin, pH, SCH, and TEWL; identify differences in these variables among different anatomical locations; and explore factors that may modify these values. MATERIAL & METHODS A cross-sectional study was conducted in 87 healthy volunteers (34 males) aged 20 to 40 years. TEWL, SCH, pH, erythema, and melanin were measured on the cheeks, volar forearms, and palms. RESULTS The lowest TEWL value corresponded to volar forearms (9.69 ± 2.94 g m-2·h-1) and the highest to palms (49.32 ± 14.55 g m-2·h-1). Erythema was more evident on cheeks than palms or volar forearms (413.51 arbitruary units [AU] vs. 259.98 AU vs. 252.02 AU). The lowest melanin index was documented for palms (92.72 ± 41.70 AU). pH levels were similar among the different locations. The erythema index was significantly higher in males versus females for all locations. Linear regression analysis adjusted for age and SCH revealed an increase in 0.45 ± 0.18 g m-2·h-1 for TEWL on the cheek and 0.32 ± 0.10 g m-2·h-1 for TEWL on the forearm for each one-year increase in age. CONCLUSION We provide normative data for individuals aged 20-40 years, across three anatomical locations, and propose a predictive model for TEWL on the cheek and forearm as a function of age and SCH.