Causes and Early Diagnosis of Vitamin B12 Deficiency: Parenteral Substitution

by Prof. Dr. med. habil. Dr. rer. nat. Wolfgang Herrmann, Dr. rer. med. Rima Obeid in volume 40/2008

In vitamin B12 deficiency, clinical deficiency symptoms occur only when the body's own reserves of 5 mg—which are primarily stored in the liver as hydroxycobalamin—are reduced to 5–10%. Treatment has to fully restore the original level. Unfortunately, however, in most German language and English language textbooks, the recommended doses of vitamin B12 are too low.

In disorders where the absorption of B12 in the gastrointestinal tract is irreversibly destroyed—for example, in chronic atrophic gastritis of the pernicious type, after gastrectomy, or after resection of the terminal ileum—parenteral substitution is necessary (1). In choosing the appropriate available medication it is important to know that cyanocobalamin is not stored in the body to the same degree as the physiological storage depot form hydroxycobalamin (2). In my opinion, hydroxycobalamin should be the preferred option. Once B12 body stores are exhausted, the deficient stores need to be completely replenished as soon as possible, to prevent deficiency symptoms. On the basis of pharmacokinetic findings (2) we have achieved good results with the following pragmatic approach: 500 µg hydroxycobalamin are given intramuscularly (of which 226 µg are retained at a retention rate of 45%—the retention rate for cyanocobalamin is only 16%) on 5 days of the week for 4 weeks (22 injections in total). This completely restores the body's deposits. To balance the daily consumption of about 2.5 µg, lifelong maintenance therapy is required, with intramuscular injections every 3 months (4 times a year).
DOI: 10.3238/arztebl.2009.0290b


Dr. med. Holmer Wohlenberg
Pfitznerstr. 1
65193 Wiesbaden, Germany

References

1. Drings P, Fölsch E, Fritsch H, Wohlenberg H: Hämatologische Krankheiten. In: Schettler G (Hrsg.) Innere Medizin. BD. II, 7. Auflage. Stuttgart:Thieme-Verlag 1987; 91

2. Heinrich HC: Metabolic basis of the diagnosis and therapy of vitamin B12-deficiency. Sem Haematol 1964; 1: 199.

3. Herrmann W, Obeid R: Causes and early diagnosis of Vitamin B12 deficiency [Ursachen und frühzeitige Diagnostik von Vitamin B12-Mangel]. Dtsch Arztebl Int 2008; 105(40): 680–5.