vitamin D (redirected from vitamin D D3)

vitamin D

n.

A fat-soluble vitamin occurring in several forms, especially vitamin D₂ or vitamin D₃, required for normal growth of teeth and bones, and produced in general by ultraviolet irradiation of sterols found in milk, fish, and eggs.

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vitamin D,

n a fat-soluble vitamin found in fatty fish and fortified dairy products and synthesized by the body via sunlight. Has been used to remedy deficiencies (including depressed levels by taking medications such as cimetidine, corticosteroids, heparin, isoniazid, phenobarbital, phenytoin, primidone, rifampin, and valproic acid), to treat osteoporosis and polycystic ovaries (in conjunction with calcium supplementation), high blood pressure, type-1 diabetes, and psoriasis. Caution in patients with hyperparathyroidism or sarcoidosis, those taking calcium channel–blocking medications or thiazide diuretics. Caution is advised for children and pregnant or lactating women, for whom the maximum daily dose is 2000 IU (50 μg). Also called
calcipotriol (topical vitamin D₃), cholecalciferol (vitamin D₃), or
ergocalciferol (vitamin D₂).

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vitamin D

a group of closely related steroids that have antirachitic properties. They commence as provitamins in both plants and animals and are converted by exposure to ultraviolet light. In plants ergosterol is converted to vitamin D₂ (the provitamin ergocalciferol) by exposure to sunlight. In animals the provitamin 7-dehydrocalciferol (formed from cholesterol) is irradiated to form vitamin D₃. Pharmaceutical vitamin D is manufactured by the ultraviolet irradiation of ergosterol.

A deficiency of vitamin D, from a nutritional deficiency of vitamin D₂ and a deficiency of exposure to sunlight so that little vitamin D₃ is formed, is characterized by the development of rickets in young animals or osteomalacia in adults.

Poisoning due to overdosing with vitamin D causes demineralization of bones and mineralization of soft tissues. The same effect is achieved by feeding on some plants. See enzootic calcinosis.

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vitamin D D₂

ergocalciferol.

vitamin D D₃

cholecalciferol.