Hereditary Metabolic Disease Reference Center, Metabolic Unit, Pediatric Department, Santa Maria's Hospital-Lisbon North University Hospital Center, EPE, Pediatric University Clinic, Faculty of Medicine, University of Lisbon, 1600-190 Lisbon, Portugal.
Laboratory of Metabolism and Genetics, Department of Pharmaceutical Sciences and Medicines, Faculty of Pharmacy, University of Lisbon, 1649-019 Lisbon, Portugal.
Nutrients. 2022 Oct 20;14(20):4397. doi: 10.3390/nu14204397.
The early diagnosis of and intervention in vitamin B12 deficiency in exclusively breastfed infants by mothers with low vitamin B12 is crucial in preventing possible irreversible neurologic damage, megaloblastic anemia, and failure to thrive. We assess the usefulness of the early detection of asymptomatic B12 deficiency related to acquired conditions and highlight the importance of monitoring serum vitamin B12 levels during pregnancy. We describe demographic, clinical, dietary, and biochemical data, including the evolution of a vitamin B12 deficiency's functional biomarkers. We enrolled 12 newborns (5 males) with an age range of 1-2 months old that were exclusively breastfed and asymptomatic. These cases were referred to our metabolic unit due to alterations in expanded newborn screening: high levels of methylmalonic acid and/or total homocysteine (tHcy). All mothers were under a vegetarian diet except three who had abnormal B12 absorption, and all presented low or borderline serum B12 level and high plasma levels of tHcy. Supplementation with oral vitB12 re-established the metabolic homeostasis of the mothers. In infants, therapy with an intramuscular injection of 1.0 mg hydroxocobalamin led to the rapid normalization of the metabolic pattern, and a healthy outcome was observed. Acquired B12 deficiency should be ruled out before proceeding in a differential diagnosis of cobalamin metabolism deficits, methylmalonic acidemia, and homocystinuria.
对于维生素 B12 摄入不足的纯母乳喂养的婴儿，母亲应早期诊断并干预，这对预防可能的不可逆神经损伤、巨幼细胞性贫血和生长发育迟缓至关重要。我们评估了早期检测与获得性疾病相关的无症状 B12 缺乏的有用性，并强调了在怀孕期间监测血清维生素 B12 水平的重要性。我们描述了人口统计学、临床、饮食和生化数据，包括与获得性疾病相关的 B12 缺乏的功能性生物标志物的演变。我们纳入了 12 名（男 5 名）年龄在 1-2 个月大的纯母乳喂养且无症状的新生儿。这些病例因扩展新生儿筛查异常而被转诊至我们的代谢单位：高甲基丙二酸和/或总同型半胱氨酸 (tHcy) 水平升高。除了 3 名存在异常 B12 吸收的母亲外，所有母亲均采用素食饮食，且均表现为血清 B12 水平低或边缘水平以及高血浆 tHcy 水平。口服 vitB12 补充剂恢复了母亲的代谢稳态。对于婴儿，肌内注射 1.0 mg 羟钴胺素可迅速使代谢模式正常化，并观察到健康的结局。在进行钴胺素代谢缺陷、甲基丙二酸血症和高同型半胱氨酸尿症的鉴别诊断之前，应排除获得性 B12 缺乏。
