Full-Body Skin Mapping for Six Biophysical Parameters: Baseline Values at 16 Anatomical Sites in 125 Human Subjects

Abstract

Background/Aim: The skin, as the outermost organ, protects against exogenous hazards (outside-in barrier) and prevents the loss of essential parts of the body (inside-out barrier). The epidermal barrier exerts several functions with specific morphological elements. Regional differences in skin functions are well known. The aim of the present study was to assess and compare skin physiological parameters in vivo at 16 anatomical sites: Barrier function in terms of transepidermal water loss (TEWL), stratum corneum (SC) hydration (assessed by capacitance), skin surface pH, skin surface temperature, erythema index and skin pigmentation were quantified at 16 anatomical sites under basal conditions. In addition, casual skin lipid level as a function of sebaceous lipids was measured on the forehead. Material and Methods: The 6 functions at the 16 anatomical sites were assessed in a cohort of 125 volunteers working in the food processing industry. These functions were quantified with noninvasive instruments, namely a Tewameter (barrier function), a Corneometer (SC hydration), a pH-meter, a Mexameter (erythema index and pigmentation), a skin surface thermometer and a Sebumeter (casual sebum level). Results: We identified ranges for the 16 anatomical locations for each instrument and some parameters could be classified into distinctive groups. Furthermore, a left-right comparison was performed at 3 sites (dorsal hand, ventral hand and ventral forearm). Certain side differences could be shown for SC hydration, surface pH, erythema index, melanin index and skin surface temperature in the 3 assessed areas. A left-to-right, statistically nonsignificant difference was also established for TEWL. Conclusion: The detected site-specific characteristics could be attributed to factors such as occlusion, different degrees of UV exposure, microcirculation and distribution of afferent and efferent nerve endings as well as fat distribution. External factors, such as life style, UV exposure and working conditions need to be taken into account. The present data are intended for an adequate selection of parameters and anatomical locations when assessing working conditions and designing clinical dermatological and pharmaceutical studies.

Do Repeated Skin Barrier Measurements Influence Each Other's Results? An Explorative Study

“…The volar forearm skin was chosen as it is one of the most frequently investigated skin areas in dermatological research due to the easy accessibility. TEWL, SCH, and pH were in concordance with previously reported results for both age groups [10,16]. For instance, we obtained systematically lower TEWL values in the aged group that is in accordance with results of a systematic review [11].…”

“…There is an extensive body of evidence today indicating that skin barrier function is indeed very similar on opposite body sites [9,10,11,12,13,23,24,25,26,27,28]. Specifically, we assumed a standard deviation of the TEWL on the volar forearm of 3 g/m 2 /h [10].…”

“…Because of large intraindividual differences in skin barrier function across the human body [6,7,8,9,10], it is important to measure standardized and comparable skin areas to reliably quantify morphological or functional skin changes over time within the same or between different groups of individuals. There is strong evidence that, for instance, the TEWL varies widely even in small skin areas like the volar forearm.…”

Skin characteristics: normative data for elasticity, erythema, melanin, and thickness at 16 different anatomical locations

“…Several studies have recently reported erythema and melanin values (42,52). Kleesz et al (42) reported a number of different anatomical locations in a predominantly male population.…”

Silicones as Nonocclusive Topical Agents

“…TEWL (AquaFlux AF200, Biox Systems Ltd., London, UK) and skin hydration (Corneometer® CM825, Courage & Khazaka Electronic GmbH, Köln, Germany) were measured according to well-established, standardized methodologies [34,35,36,37]. Prior to biophysical measurements, volunteers acclimatized in a temperature- (20.3 ± 0.5°C) and relative humidity-controlled (55.6 ± 2.2%) room for 30 min with uncovered forearms.…”