Vitamin B12 in serum

Reference values ​​of vitamin B12 concentration in blood serum: in newborns - 160-1300 pg / ml, in adults - 200-835 pg / ml( average values ​​300-400 pg / ml).

Vitamin B12( cyanocobalamin) is necessary for the normal maturation of red blood cells. It performs the function of coenzyme in the synthesis of nucleic acids( DNA and RNA) and methionine from homocysteine. Methionine is necessary for the conversion of folic acid into folinic, which provides the normoblastic type of hematopoiesis. In addition, vitamin B12 provides the synthesis of LP in myelinated tissue and glutathione. Therefore, vitamin B12 deficiency is accompanied by the development of megaloblastic anemia, neutropenia and neurological disorders( funicular myelosis).Immunodeficiency in the case of vitamin B12 deficiency is associated with the formation of hy-persemented neutrophils, characterized by a decreased activity of the oxygen-dependent bactericidal mechanism, which is necessary for the destruction of intracellular bacteria and viruses.

To vitamins of group B12 are several cobalamins, contained exclusively in products of animal origin. Almentary insufficiency of vitamin B12 is rarely recorded. Absorption of vitamin B12 occurs in the distal parts of the ileum. It is possible only after the formation of a vitamin complex with an internal factor - glycoprotein, secreted in the stomach. The specific transporter protein transkobalamin II carries cobalt-new transport in blood plasma. Absorption of the vitamin depends on the following factors: secretion of the internal factor in the stomach;the integrity of the mucosa of the distal ileum;presence in the plasma of transcobalamin II in sufficient quantity. Vitamin B12 is necessary for the growth of some bacteria of the intestine, which inhibit the absorption of this vitamin, competing for it with intestinal cells. Therefore, the intestinal microflora can influence the absorption of vitamin B12.

Insufficiency of vitamin B12 in the body, like folic acid, causes megaloblastic anemia. With true pernicious anemia, the impairment of absorption of vitamin B12 is due to the presence of AT to the internal factor. In contrast to the deficiency of folic acid, with deficiency of vitamin B12 degeneration of the spinal cord is possible. Although the manifestations of megaloblastic anemia with vitamin B12 deficiency can be eliminated by folic acid, this drug should never be prescribed for pernicious anemia, as it not only does not improve the condition of patients with neurological disorders, but can even exacerbate it. The determination of the vitamin B12 concentration is used in the diagnosis of macrocytic and megaloblastic anemia. It should be borne in mind that the vitamin B12 deficiency develops slowly, for many years( after gastroectomy - up to 12 years).Changes in the vitamin B12 content for various diseases and pathological conditions are reflected in the table.

Table Diseases and conditions in which the concentration of vitamin B12 in the blood serum