[Low serum vitamin B 12 level and vitamin B 12 deficiency in the elderly. When should supplement be provided?]

Low serum vitamin B12 levels and vitamin B12 deficiencies are frequently found in the elderly. The full syndrome of a vitamin B12 deficiency is rather simple to diagnose. The large applicability of the vitamin B12 assay also gives rise to many probably incomplete features. Low/low-normal vitamin B12 levels in screening procedures raise uncertainty whether this finding represents deficiency and should be followed by supplementation. In this paper the occurrence of low serum levels of vitamin B12 are discussed. To assess the clinical relevance of low/low-normal outcomes supplementary diagnostic procedures will be needed. Within this scope we illustrate the d.o.s.-test and the MMA-assay. Especially the latter will probably provide more answers to the treatment question. Systematic research is needed to clarify this issue. Meanwhile supplementation of all low and low-normal outcomes of the B12-assay seems the best answer.