Clinical Research: B12 Deficiency and the Brain in Infants
Alan Gaby, MD
Author: Irevall T, et al
Reference: B12 deficiency is common in infants and is accompanied by serious neurological symptoms. Acta Paediatr 2017;106:101-104.
Design: Laboratory analysis and open-label trial.
Participants: One hundred twenty-one infants in Sweden who were hospitalized between 2004 and 2012 with severe neurological symptoms at less than one year of age. All infants were tested for vitamin B12 deficiency, which was defined as low serum cobalamin and/or increased homocysteine and/or increased methylmalonic acid levels.
Study Medication and Dosage: Infants diagnosed with vitamin B12 deficiency received vitamin B12 replacement therapy.
Primary Outcome Measures: Proportion of patients with vitamin B12 deficiency, and neurological development after vitamin B12 replacement therapy.
Key Findings: Thirty-five infants (29%) had vitamin B12 deficiency, which was diagnosed at an average age of 1.7 months. Seizures, apnea, and other apparent life-threatening events were common symptoms. After vitamin B12 replacement therapy, neurological development was normal.
Practice Implications: These results demonstrate that B12 deficiency is common in infants presenting with severe neurological symptoms such as seizures and apparent life-threatening events, and that these abnormalities can be corrected by vitamin B12 replacement therapy. While an elevated homocysteine level in adults indicates folate deficiency more often than vitamin B12 deficiency, a high homocysteine level in infants has been found in most cases to be due to vitamin B12 deficiency. In a previous study, 81 of 105 children presenting with feeding difficulties, subtle neurologic signs, or delayed psychomotor development had an elevated plasma homocysteine concentration. Seventy-nine of the 81 infants thought to have vitamin B12 deficiency were randomly assigned to receive, in double-blind fashion, a single intramuscular injection of hydroxocobalamin (400 µg) or a sham injection (placebo). The median improvement in motor function (as determined by the Alberta Infants Motor Scale) was significantly greater in the vitamin B12 group than in the placebo group. In addition, a higher proportion of infants in the B12 group than in the placebo group showed improvement in regurgitations (69% vs. 29%; p = 0.003). Thus, vitamin B12 deficiency should be considered in the differential diagnosis of both severe and mild neurological and developmental abnormalities in infants.
Torsvik I, et al. Cobalamin supplementation improves motor development and regurgitations in infants: results from a randomized intervention study. Am J Clin Nutr 2013;98:1233-1240.