The intra‐ and inter‐individual variability and reliability of transepidermal water loss measurements

Abstract

An analysis of variance was conducted to estimate the intra- and inter-individual variations in TEWL on the forearms, by sites (8 measurement sites) and by days (10 different days), in 30 non-exposed healthy individuals. The estimated intra- and inter-individual variations, by sites, were 15.5% and 84.5%, respectively, the sum of the 2 components always being 100%. With the exclusion of the 2 most distal sites near the wrist, which had significantly higher baseline TEWL values and fluctuations in TEWL, an improvement in the intra-individual variation was obtained. Thus, of the 6 sites, the estimated intra- and inter-individual variations were 8.4% and 91.6%, respectively. This finding supports the exclusion of these most distal sites for future investigations. The estimated intra- and inter-individual variations, by days, were 20.6% and 79.4%, respectively. The low site-to-site (8.4%) and day-to-day (20.6%) intra-individual variations, as compared to the large inter-individual variations of the same (91.6% and 79.4%), indicate that baseline TEWL is a stable personal characteristic. Thus, individual susceptible to irritant contact dermatitis (ICD), due to occupational exposure, may be reliably characterized by utilizing their baseline TEWL values, for "prediction" of risk in epidemiological field studies.

Intra‐ and inter‐individual variations in transepidermal water loss on the face: facial locations for bioengineering studies

“…The reliability of TEWL as a stable indicator of barrier function depends heavily on the intra-individual variation being smaller than the inter-individual variation (12). For the volar forearm as a region for bioengineering studies, this condition is generally accepted to be fulfilled.…”

Review of methods used for quantifying excess water in over-hydrated skin using evaporimetry

“…In particular, there is some evidence that baseline TEWL may vary between dominant and non‐dominant arms (23, 24) although some have found no difference (25, 26). Similarly, there is evidence for TEWL varying with position on the volar forearm (24, 27), although some have found little variation, provided the skin near the wrist and elbow creases is avoided (25, 28, 29). TEWL also varies with skin temperature and so the ambient temperature should be noted and subjects should be acclimatised to ambient conditions for at least 15–30 min before measurements are made (8).…”

Transepidermal water loss reflects permeability barrier status: validation in human and rodentin vivoandex vivomodels

“…‘Barrier’ is defined in the Merriam‐Webster Online Dictionary (1) as either (a) ‘something material that blocks or is intended to block passage’ or (b) ‘a natural formation or structure that prevents or hinders movement or action’. The assessment of epidermal permeability barrier function, routinely employs measurements of transepidermal water loss (TEWL), which have been presented to provide information about permeability barrier status under either normal, experimentally perturbed, or diseased conditions (2). The degree of barrier disruption, again assessed as TEWL, also correlates with drug penetration of different compounds, in concordance with an ‘outside‐in’ concept of barrier function (3–5).…”