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Treatment of vitamin B12 deficiency
Medical expert of the article
Last reviewed: 06.07.2025
Prevention is carried out in case of gastrocnemius and ileal resection.
The initial daily dose of vitamin B 12 is 0.25-1.0 mg (250-1000 mcg) for 7-14 days. As an alternative regimen (if the body is able to store the vitamin for a long time), intramuscular administration of the drug at a dose of 2-10 mg (2000-10,000 mcg) monthly is used. In most cases, therapy is lifelong.
In transcobalamin II deficiency, the therapeutic response is achieved by administering high doses of vitamin B 12, the serum cobalamin content must be maintained at a sufficiently high level. Adequate disease control is ensured by intramuscular administration of 10 mg (10,000 mcg) of vitamin B 12 2-3 times a week.
In methylmalonic aciduria and impaired synthesis of cobalamin coenzymes, vitamin B 12 is prescribed at a dose of 0.01-0.02 mg (10-20 mcg) per day, but for some patients this dose is insufficient. It is possible to administer the drug by cordocentesis.
In B 12 -deficiency megaloblastic anemia, an increase in the number of reticulocytes is noted on the 3rd-4th day of treatment, the maximum - on the 6th-8th day, by the 20th day of treatment the number of reticulocytes is normalized. The content of reticulocytes is inversely proportional to the severity of anemia. In the bone marrow, megalocytosis begins to disappear 6 hours after the administration of vitamin B 12 and is completely absent 72 hours after the start of treatment. A decrease in the severity of neurological symptoms is noted after 48 hours, the lag in psychomotor development ceases after several months. Residual neurological changes are often noted in patients.
It is important to remember that the administration of folic acid to patients with megaloblastic anemia due to vitamin B12 deficiency leads to the reverse development of only hematological symptoms, while neurological symptoms in most cases progress or remain unchanged, so its use is contraindicated.