Does Dry Skin Indicate Defective Epidermal Permeability Barrier?

The document discusses the relationship between dry skin and the function of the epidermal permeability barrier. It suggests that dry skin is not an indicator of a defective epidermal permeability barrier, as previously speculated. Dry skin is primarily a result of low levels of stratum corneum hydration, which is determined by the content of natural moisturizers in the skin. The function of the epidermal permeability barrier is mainly regulated by intercellular lipids and structural proteins in the stratum corneum. The study found no negative correlation between stratum corneum hydration levels and transepidermal water loss (TEWL), an indicator of epidermal permeability barrier function, in normal human skin, ichthyoses lesions of patients, or sebaceous gland-deficient mice. Instead, a positive correlation was observed in normal human skin.