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Menadione (vitamin K3) |
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Menadione is a fat-soluble vitamin precursor that is converted into menaquinone in the liver. Vitamin K1 and vitamin K2 are the
naturally occurring types of vitamin K. Menadione (K3) is not considered a natural vitamin K, but rather a synthetic analogue that acts as a provitamin. Also called menadione, this yellowish, synthetic crystalline substance is converted into the active form of the K2 vitamin inside of the animal body. Menadione is necessary for the production of prothrombin and five other blood clotting factors in humans. It also regulates bone calcification. Vitamin K3 plays an important role in the synthesis of hepatic prothrombin and in the coagulation process, having in this way a strong antihaemorrhagic effect. It acts on capillary endothelia and on fibrinogen. Vitamin K3 is the form most utilized as a supplement. The vitamin K3 deficiency determines haemorrhages and hypoprothrombinaemia. In large doses, vitamin K3 activates the reticulohistiocytic system, produces diuresis (in general oedema), stimulates the liver and the bone marrow functions. Newborns that are administered too great a dosage of vitamin K3 can suffer from kernicterus, a form of severe brain damage that may produce decreased movement, loss of appetite, seizures, deafness, mental retardation, and even death. The primary known function of vitamin K is to assist in the normal clotting of blood, but it may also play a role in normal bone calcificaton. |
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