Practical Use and Significance of Transepidermal Water Loss Measurements

Transepidermal water loss (TEWL) is universally recognized to be a measure of skin barrier function, either at baseline, after experimentally induced barrier abrogation or following topical treatments. In mammals, it is also known as “insensible water loss” as it is a process over which organisms have little physiological control. Measurements of TEWL (grams per square meter per hour) is useful for identifying skin damage caused by certain chemicals, physical insult (such as “tape stripping”), or pathological conditions such as eczema [11], as rates of TEWL increase in proportion to the level of damage even before the damage is clinically visible. It may thus be considered as the tool that evaluates the water barrier function of the epidermis.