Transepidermal Water Loss
The passive diffusion of water through the skin barrier to the external environment, used as a clinical measure of barrier integrity.
Full Definition
Transepidermal water loss (TEWL) quantifies how much moisture escapes through the skin's outer layers without sweating, serving as a key indicator of epidermal barrier function. Elevated TEWL values signal barrier compromise, a common concern following ablative procedures, chemical peels, or in patients with sensitised skin. In cosmetic dermatology literature, TEWL is frequently reported as an efficacy endpoint in clinical study write-ups and ingredient substantiation documents. Editors working on such documents should verify that units (g/m²/h) are consistently applied and that TEWL is not confused with general skin hydration measurements.
Usage
Usage note: Always expand on first use as 'transepidermal water loss (TEWL)'. Confirm units are g/m²/h throughout a document for consistency.
In Context
- "Post-procedure TEWL measurements confirmed a transient compromise of the stratum corneum's barrier function." — Clinical study results section
- "The manuscript incorrectly labeled the corneometer readings as TEWL data; these instruments measure hydration, not transepidermal water loss." — Peer-review editorial note