[Update of clinical findings in cobalamin deficiency: personal data and review of the literature].

PURPOSE: During last decades, several progresses have been made in the diagnosis of cobalamin (vitamin B12) deficiency. Routine used of cobalamin standardized assays have potentially modified the frequency and the type of hematologic abnormalities. CURRENT KNOWLEDGE AND KEY POINTS: Current studies on cobalamin deficiency, including more precise definitions and the description of new etiologies of cobalamin deficiency in adults, as the food-cobalamin malabsorption syndrome, show that hematological abnormalities are generally incomplete compared to historical descriptions of megaloblastic anemia. Nevertheless, they include severe manifestations in 10% of the patients: pancytopenia, severe anemia (hemoglobin < 6 g/dl) or hemolytic anemia and pseudo thrombotic microangiopathy related to cobalamin deficiency. These studies also show the efficacy of new treatment modalities including oral cobalamin administration. PROSPECTS AND PROJECTS: Future studies will confirm these data with the routine use of the new cobalamin assay: holotranscobalamin and validate the usefulness of oral cobalamin therapy.