Skin aging and sex hormones in women -- clinical perspectives for intervention by hormone replacement therapy.

The skin, the largest organ of the body, is the organ in which changes associated with aging are most visible. The skin is a target organ for various hormones, and sex steroids have a profound influence on the aging process. A decrease in sex steroids thus induces a reduction of those skin functions that are under hormonal control. Keratinocytes, Langerhans' cells, melanocytes, sebaceous glands, collagen content and the synthesis of hyaluronic acid, for example, are under hormonal influence. Topical application of estrogens has a positive effect on skin aging parameters, whilst numerous studies have also shown the positive influence of systemic hormone replacement therapy on skin aging. As an alternative treatment, phytohormones may be administered, with the structural similarity to 17beta-estradiol explaining their estrogen-like effects. However, isoflavonoids exhibit an inferior biological potency to synthetic estrogens. Although a large number of publications have documented the effects of sex hormones on the aging process, it is obvious that hormone replacement should not be administered as an independent treatment for skin aging.