Stratum corneum water content and transepidermal water loss (SCWC and TEWL)

Stratum corneum water content (SCWC) and transepidermal water loss (TEWL) are fundamental physiological parameters used to assess the integrity of the skin's permeability barrier. SCWC represents the hydration level of the outermost epidermal layer, which is maintained by natural moisturizing factors (NMFs) and a complex lipid matrix (StatPearls, 2023). TEWL is the continuous diffusion of water from the dermis through the epidermis to the external environment; elevated TEWL is a primary indicator of barrier dysfunction and is often associated with increased skin sensitivity and inflammation (PubMed, 2021). Although these are clinical measurements rather than specific molecular targets like receptors or enzymes, they are central to the pathology of dermatological diseases such as atopic dermatitis and psoriasis. Therapeutic interventions, including emollients, humectants, and anti-inflammatory drugs, aim to restore these parameters to homeostatic levels to improve skin health and prevent pathogen entry. These metrics are frequently utilized as primary or secondary endpoints in clinical trials to evaluate the efficacy of new dermatological therapies.

Other names

Skin barrier functionSkin hydrationInsensible water lossEpidermal water fluxStratum corneum hydration

Topical agents typically act via occlusion to physically block water loss or humectancy to chemically bind water within the stratum corneum, while systemic agents may improve barrier function by reducing underlying inflammation that disrupts lipid synthesis (Journal of Clinical and Aesthetic Dermatology, 2017).