What is the primary cause of transepidermal water loss?

The primary cause of transepidermal water loss is related to decreased barrier function and severe dehydration. The skin serves as a protective barrier to prevent moisture loss. When the barrier function is compromised, whether due to damage, aging, or various skin conditions, the ability of the skin to retain moisture diminishes, leading to increased water loss. Severe dehydration can exacerbate this condition, making it even more difficult for the skin to maintain its moisture level and protect against transepidermal water loss.

The other options describe factors that may influence skin condition but do not directly cause transepidermal water loss in the same fundamental way. For instance, obstructed sweat glands may affect sweating but are not primarily responsible for water loss at the epidermal level. Excessive hydration can temporarily swell skin cells but does not directly address the barrier function. High humidity environments can actually help reduce transepidermal water loss by preventing moisture evaporation from the skin surface, rather than being a cause of it.