Dry Skin and its Various Forms
A large portion of the population suffers from dry skin. Different forms and degrees of severity can be distinguished. Dry skin is especially common in children under 10 and older people over 60. Between the ages of 10 and 60, significantly more women than men suffer from dry skin. Some 15 to 20 percent of the population suffers from an atopic disposition to dry skin (xerodermia).
Causes of dry skin
Skin dryness is dependent on various external (exogenous) and internal (endogenous) factors.
- Typical exogenous factors are climate and environmental factors, including skin contact with chemicals like cleansing agents and solvents. Further exogenous factors are UV exposure and the influence of skincare and therapeutic preparations such as medicines (topical and systemic).
- The endogenous factors that lead to dry skin or contribute to its development include genetic predisposition, biological skin ageing, hormonal influence and certain dermatological and internal diseases (atopic dermatitis, psoriasis, ichthyosis and diabetes).
Forms of dry skin
There are a variety of causative factors and levels of severity of dry skin ranging from mild to clearly pathological forms. In practice, the individual forms are not always clearly distinguishable. However, in general one can distinguish between problem dry skin and extremely dry skin. In both types, the cause is essentially a deficit of natural moisturizing factors (i), especially urea (i). A special form, due to its pathogenesis, is atopic dry skin, in which a disturbed fatty acid metabolism of the skin plays a major role.
Dry and rough skin
Characteristics of problem dry skin are:
- Mild scaling
- Roughness
- Feeling of tightness
- Possibly itching
The reduced water binding capacity is an important factor in problem dry skin. It depends on the concentration of natural moisturizing factors (i) (NMF), the most important of which are urea (i), amino acids and the epidermal lipids (particularly triglycerides, free fatty acids and cholesterol).
Urea is formed during the breakdown of specific amino acids, particularly arginine, in the cell cornification process. In cornification disorders, there is a deficiency of these amino acids, particularly arginine. This leads to a marked reduction in the concentration of urea (i), and the natural moisturizing function is reduced. In comparative measurements clinically dry skin was shown to have a 50 percent lower urea (i) concentration than healthy skin. This lack of natural moisturizing factors (i) (especially urea (i)) leads to increased transepidermal water (i) loss (TEWL).
Application of a skincare preparation containing approximately 3 to 5 percent urea (i) can effectively compensate for the deficit in the natural moisturizing factor urea (i). An increase in the water binding capacity of the skin follows and the skin condition improves or is normalized.
Urea is a natural moisturizing factor and increases the water binding capacity of the skin. Low urea (i) concentrations lead to increased transepidermal water (i) loss.
Very dry and scaly skin
The characteristics of extremely dry skin found for example in the elderly or on the hands after extreme dehydration are:
- Roughness
- Chapping with a tendency to formation of rhagades
- Callus formation / scaling
- Frequently itching
Unlike with problem dry skin, the application of a low concentration of urea (i) is not sufficient for extremely dry skin. Often a therapy with formulations containing 10% urea (i) is required.
