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The consequences of vitamin D deficiency primarily concern bone health. The vitamin D analog called calcipotriene or calcipotriol has also been used as a treatment for chronic plaque psoriasis, either alone or in combination with corticosteroids (9, 10).Ĭovering exposed skin or using sunscreen whenever outside are risk factors for vitamin D deficiency. Several studies found that topical use of calcitriol (3 μg/g) ointment is safe and may be an effective treatment for plaque-type psoriasis (6-8). Topical applicationĬalcitriol (1,25-dihydroxyvitamin D 3) has been used topically to treat certain skin conditions, including psoriasis, a skin condition that involves a hyperproliferation of keratinocytes. Keratinocytes in the epidermis possess hydroxylase enzymes that locally convert vitamin D to 1,25-dihydroxyvitamin D 3 (3-5), the form that regulates epidermal proliferation and differentiation (see Metabolism in keratinocytes). Most of the physiological effects of vitamin D in the body are related to the activity of 1,25-dihydroxyvitamin D 3 see the article on Vitamin D. In the kidneys, the 25-hydroxyvitamin D 3-1-hydroxylase enzyme catalyzes a second hydroxylation of 25-hydroxyvitamin D, resulting in the formation of 1,25-dihydroxyvitamin D 3 (calcitriol, 1α,25-dihydroxyvitamin D] - the most potent form of vitamin D (2). Vitamin D 3 enters the circulation and is transported to the liver, where it is hydroxylated to form 25-hydroxyvitamin D 3 (calcidiol the major circulating form of vitamin D). Hence, vitamin D is actually more like a hormone than a vitamin, a substance that is required from the diet. Solar ultraviolet-B radiation (UVB wavelengths of 290 to 315 nanometers) stimulates the production of vitamin D 3 from 7-dehydrocholesterol (7-DHC) in the epidermis of the skin (see Production in Skin) (1). Sunlight exposure is the primary source of vitamin D for most people. See the Skin Health Overview article Overview Healthcare Professional Continuing Education.Chlorophyll and Metallo-Chlorophyll Derivatives.