Transepidermal Water Loss
Pronunciation: T-E-W-L (spelled out) or /tuːl/ (colloquial)
Also written as: TEWL — Transepidermal Water Loss
The passive diffusion of water vapour through the epidermis to the skin surface, used as an objective measure of barrier integrity.
Full Definition
Transepidermal water loss (TEWL) quantifies the rate at which water evaporates through intact skin, expressed in g/m²/h. It is a primary objective endpoint in dermatological research for assessing both disease severity and the efficacy of emollient or barrier-repair therapies. Elevated TEWL values indicate compromised barrier integrity and are seen in conditions such as atopic dermatitis, psoriasis, and ichthyosis. Editors must ensure the acronym TEWL is introduced with its full form on first use and that measurement units are consistently reported. The term is distinct from insensible perspiration, which includes sweat gland output.
Usage
Usage note: Spell out in full on first mention; TEWL is acceptable thereafter. Always accompany values with units (g/m²/h).
In Context
- "Baseline TEWL measurements were recorded using a closed-chamber instrument before treatment commenced." — Methods section of a clinical study
- "A significant reduction in transepidermal water loss confirmed the emollient's barrier-repair properties." — Discussion section of a dermatology journal article