[Hypervitaminemia B12 (high level of cobalamin): physiopathology, role and interest in clinical practice].

Hypervitaminemia B12 or high serum level of cobalamin B12 is a frequent and clinical underestimated abnormality. Clinically, it can be sometimes paradoxically accompanied by signs of deficiency reflecting a functional deficit in relation to qualitative abnormalities related to defects in tissue uptake and action of vitamin B12. Etiological profile of hypervitaminemias B12 has mostly serious disease entities and for which early diagnosis is crucial to the plan rather than prognostic. These entities are represented mainly by solid malignancies, hematological malignancies and liver diseases. This reflects the potential significance that may have the dosage of vitamin B12 as an early marker of diagnosis of these diseases. Codified approach is needed to determine the potential indications of the search for a hypervitaminemia B12 and practice what to do to pass before the discovery of a high serum level of cobalamin.