Transepidermal water loss of the diseased skin : evidence summary and clinical applications

Abstract

Introduction: Transepidermal water loss (TEWL) is a biophysical property of the skin that represents many physiological states. Numerous studies have evaluated the magnitude of TEWL in patients and implicated its values in various clinical applications; however, these data have not been systematically reviewed. Objectives: To describe and compare the magnitude of TEWL among adult patients with different pathological conditions. Methods: A systematic search was performed on Pubmed, Embase, and Web of Science databases to identify publications involving the measurement of TEWL in adult humans. Primary studies that recruited subjects diagnosed with dermatological or non-dermatological diseases, evaluated TEWL in-vivo, and reported its value along with their distribution were included. TEWL estimates from included studies were summarised with mean and standard deviations per disease groups sharing similar pathology. The clinical implications of TEWL were also explored. Results: Five hundred and eighty-five studies were included. The conditions in which TEWL estimates have been reported, in order of frequency, were inflammatory dermatoses, sclerotic diseases, pigmentary diseases, wounds and ulcers, tumours, scalp diseases, and other medical conditions. TEWL has been most extensively studied in atopic dermatitis; its TEWL values were consistently higher than normal controls and correlated with skin barrier disruption. TEWL estimates in other diseases followed distinctive trends, with most inflammatory diseases showing higher-than-normal TEWL values. TEWL estimates of subjects with some degree of skin barrier dysfunctions (e.g., subjects with xerosis cutis, diabetic patients) did not differ from a healthy population. Some diseases demonstrated lower TEWL than controls (e.g., scleroderma, leprosy, diabetic neuropathy). Hence, TEWL estimates of non-atopic skin may reflect derangements of other TEWL-regulating structures in addition to skin barrier disruption. For clinical utilities, TEWL measurements can be used to assess topical drugs’ irritation potentials and monitor the disease activity of atopic dermatitis. Conclusion: The magnitude of TEWL is abnormally elevated by atopic dermatitis, congenital ichthyosis, and most other inflamed skin lesions due to skin barrier defects. TEWL values in other non-atopic diseases vary depending on the disease’s nature and may not always represent skin barrier disruption like atopic dermatitis. Implication of thematic paper: This thematic paper details the physiological role of transepidermal water loss (TEWL) and what factors affect its values when quantified in-vivo. It also comprehensively reviews currently available data on TEWL estimates of subjects with dermatological and non-dermatological diseases compared to healthy volunteers and which physiological parameters TEWL values could represent for each disease. Since this information has not been comprehensively summarised elsewhere, this paper provides valuable information for researchers or physicians interested in incorporating TEWL measurements in their works.