• The water content of stratum corneum is reduced (13% of water for normal skin and less of 10% for dry skin).
• An abnormal keratinization modifying the stratum corneum equilibrium Build-up of dead skin cells.

One of the most common causes of dull skin is the build of dead skin cells (keratinocytes) on the surface. Keratinocytes are created at the base of the epidermis (stratum basale) and progressively move towards the outer layer of the epidermis (stratum corneum). During this migration to the outer layer, keratinocytes become flatter, drier and are eventually shed from the skin. Inadequate shedding leads to a build-up of dead, dry skin cells, which makes the skin look dull and dry. This can be repaired by improving skin exfoliation through topical skincare and exfoliative skin treatments and corneocytes cohesion (abnormal lipid compartment).

• A decrease in barrier function, which increases in the passive rate of transepidermal water loss.

Two types of dry skin can be distinguished

Acquired dry skin and constitutional dry skin

Acquired dry skin may arise from normal, or sometimes even greasy skin, which is rendered temporarily and locally dry by external factors such as solar radiation, exposure to extreme climate (cold, heat, wind, dryness), exposure to chemicals, or various therapeutic measures (lithium, retinoids). Constitutional dry skin can be nonpathologic (senile skin, fragile skin) or pathologic (ichtyoses,dry skin of atopic dermatitis, hypothyroidism, uremia).

Loss of natural hyaluronic acid

With age, menopause, lifestyle choices and sun exposure, the epidermis becomes depleted of natural hyaluronic acid, the natural hydrator of the skin. This results in the skin looking more dry and wrinkled. Hyaluronic acid can be replenished by treatments such as hydrafacial, mesotherapy, biorevitalisation and microneedling.

Treatment