Vitamin B12 deficiency
Vitamin B12 deficiency
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DOI：
10.1038/nrdp.2017.40
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发表时间：
2017-06-29
影响因子：
81.5
通讯作者：
Yajnik, Chittaranjan
中科院分区：
文献类型：
--
作者：
Green, Ralph;Allen, Lindsay H.;Yajnik, Chittaranjan
维生素B-12（B12;也称为钴胺素）是一种B族维生素，在细胞代谢中具有重要作用，特别是在DNA合成、甲基化和线粒体代谢中。临床B12缺乏与经典的血液学和神经系统的表现是相对罕见的。然而，根据所使用的定义，亚临床缺陷影响2.5%至26%的一般人群，尽管临床相关性尚不清楚。维生素B12缺乏症可以影响所有年龄段的人，尤其是老年人。婴儿、儿童、青少年和育龄妇女在限制含B12动物源性食物饮食摄入的人群中也有很高的缺乏风险。缺乏是由于摄入不足、生物利用度不足或吸收不良造成的。血液中B12转运的中断或细胞摄取或代谢受损会导致细胞内缺乏。B12状态的诊断生物标志物包括循环总B12和转钴胺素结合B12水平降低，以及同型半胱氨酸和甲基丙二酸水平异常升高。然而，临床和亚临床缺陷分类的确切截止值仍有争议。管理取决于B12补充剂，通过高剂量口服途径或通过胃肠外给药。本书介绍了目前关于B12缺乏症的知识，并强调了诊断方法的改进以及关于B12缺乏症的患病率，原因和表现的概念转变。
Vitamin B-12 (B12; also known as cobalamin) is a B vitamin that has an important role in cellular metabolism, especially in DNA synthesis, methylation and mitochondrial metabolism. Clinical B12 deficiency with classic haematological and neurological manifestations is relatively uncommon. However, subclinical deficiency affects between 2.5% and 26% of the general population depending on the definition used, although the clinical relevance is unclear. B12 deficiency can affect individuals at all ages, but most particularly elderly individuals. Infants, children, adolescents and women of reproductive age are also at high risk of deficiency in populations where dietary intake of B12-containing animal-derived foods is restricted. Deficiency is caused by either inadequate intake, inadequate bioavailability or malabsorption. Disruption of B12 transport in the blood, or impaired cellular uptake or metabolism causes an intracellular deficiency. Diagnostic biomarkers for B12 status include decreased levels of circulating total B12 and transcobalamin-bound B12, and abnormally increased levels of homocysteine and methylmalonic acid. However, the exact cut-offs to classify clinical and subclinical deficiency remain debated. Management depends on B12 supplementation, either via high-dose oral routes or via parenteral administration. This Primer describes the current knowledge surrounding B12 deficiency, and highlights improvements in diagnostic methods as well as shifting concepts about the prevalence, causes and manifestations of B12 deficiency.