Lindenbaum J, Rosenberg I H, Wilson P W, Stabler S P, Allen R H
Department of Medicine, Columbia-Presbyterian Medical Center, New York, NY 10032.
Am J Clin Nutr. 1994 Jul;60(1):2-11. doi: 10.1093/ajcn/60.1.2.
To determine whether the increased prevalence of low serum cobalamin concentrations in elderly people represents true deficiency, serum concentrations of cobalamin and folate and of metabolites that are sensitive indicators of cobalamin deficiency were measured in 548 surviving members of the original Framingham Study cohort. Serum cobalamin concentrations < 258 pmol/L were found in 222 subjects (40.5%) compared with 17.9% of younger control subjects (P < 0.001). Serum methylmalonic acid and total homocysteine concentrations were markedly elevated in association with cobalamin values < 258 pmol/L in 11.3% and 5.7%, respectively, of the cohort. Both metabolites were increased in 3.8% of the cohort, associated with significantly lower erythrocyte counts and higher mean cell volumes. Serum metabolites correlated best with serum cobalamin values, even when subnormal determinations were excluded. The prevalence of cobalamin deficiency was > or = 12% in a large sample of free-living elderly Americans. Many elderly people with "normal" serum vitamin concentrations are metabolically deficient in cobalamin or folate.
为了确定老年人血清钴胺素浓度升高是否代表真正的缺乏，我们对弗明汉姆心脏研究队列中548名存活成员的血清钴胺素、叶酸以及钴胺素缺乏敏感指标的代谢物浓度进行了测量。222名受试者（40.5%）的血清钴胺素浓度<258 pmol/L，而年轻对照受试者中这一比例为17.9%（P<0.001）。在该队列中，分别有11.3%和5.7%的受试者血清甲基丙二酸和总同型半胱氨酸浓度与钴胺素值<258 pmol/L显著升高相关。两种代谢物均升高的受试者占该队列的3.8%，与红细胞计数显著降低和平均细胞体积升高相关。即使排除低于正常的测定值，血清代谢物与血清钴胺素值的相关性依然最佳。在大量自由生活的美国老年人样本中，钴胺素缺乏的患病率≥12%。许多血清维生素浓度“正常”的老年人在代谢上存在钴胺素或叶酸缺乏。
