cyanocobalamin /sī′ənōkōbal″əmin/ [Gk, kyanos + Ger, kobald, mine goblin] , a red crystalline, water-soluble substance that is the common pharmaceutic form of vitamin B12. It is involved in the metabolism of protein, fats, and carbohydrates; normal blood formation; and neural function. It is the first substance containing cobalt found to be vital to life. It cannot be produced synthetically but can be obtained from cultures of Streptomyces griseus. Rich dietary sources are liver, kidney, meats, fish, and dairy products. Deficiency can be caused by the absence of intrinsic factor (produced in the stomach), which is necessary for the absorption of cyanocobalamin from the GI tract. Deficiency can also occur in persons whose diet is strictly vegetarian, thereby excluding meat and dairy sources of the nutrient. Symptoms of deficiency include nervousness, neuritis, numbness and tingling in the hands and feet, poor muscular coordination, and menstrual disturbances. Cyanocobalamin (via injection) is used in the prophylaxis and treatment of pernicious anemia, tropical and nontropical sprue, and other macrocytic and megaloblastic anemias. It is relatively nontoxic, even when administered in amounts greater than those recommended for therapeutic purposes. Also called antipernicious anemia factor, vitamin B12, extrinsic factor. See also intrinsic factor, pernicious anemia.
