|
Carotenemia or carotenaemia (xanthaemia) is the presence of the orange pigment carotene in blood from excessive intake of carrots or other vegetables containing the pigment resulting in increased serum carotenoids. Carotenoids are lipid-soluble compounds that include alpha- and beta-carotene, beta-cryptoxanthin, lycopene, lutein, and zeaxanthin. The primary serum carotenoids are beta-carotene, lycopene, and lutein. Serum levels of carotenoids vary between region, ethnicity, and sex in the healthy population. All are absorbed by passive diffusion from the gastrointestinal tract and are then partially metabolized in the intestinal mucosa and liver to vitamin A. From there they are transported in the plasma into the peripheral tissues. Carotenoids are eliminated via sweat, sebum, urine, and gastrointestinal secretions. Carotenoids contribute to normal-appearing human skin color and are a significant component of physiologic ultraviolet photoprotection. An excess of carotenoids, being eliminated via sweat, may cause a marked orange discoloration of the outermost skin layer. This benign and reversible condition – which is most easily observed in light-skinned people and may be mistaken for jaundice – is known as carotenosis or carotenoderma. Carotenemia most commonly occurs in vegetarians and young children. Carotenemia is more easily appreciated in light-complexioned people, and it may present chiefly as an orange discolouration of the palms and the soles in more darkly pigmented persons.〔(eMedicine - Carotenemia : Article by Robert A Schwartz )〕 Carotenemia does not cause selective orange discoloration of the conjunctival membranes over the sclerae (whites of the eyes), and thus is usually easy to distinguish from the yellowing of the skin and conjunctiva caused by bile pigments in states of jaundice. Carotenoderma is deliberately caused by beta-carotenoid treatment of certain photo-sensitive dermatitis diseases such as erythropoietic protoporphyria, where beta carotene is prescribed in quantities which discolor the skin. These high doses of beta carotene have been found to be harmless in studies, though cosmetically displeasing to some. In a recent meta analysis of these treatments, however, the effectiveness of the treatment has been called into question. ==Physiology== Carotenoids are deposited in the intercellular lipids of the stratum corneum, and the color change is most prominent in regions of increased sweating and thickness of this layer. This includes the palms, soles, knees, and nasolabial folds, although the discoloration can be generalized. The primary factor differentiating carotenoderma from jaundice is the characteristic sparing of the conjunctivae in carotenoderma, which would be involved in jaundice if the bilirubin is at a level to cause skin findings. In contrast to jaundice, carotenoderma is reported to be better observed under artificial light. It is of note that lycopenemia is specifically associated with discoloration of the soft palate and deposition in the liver parenchyma. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Carotenosis」の詳細全文を読む スポンサード リンク
|