Should we worry about elevated B12 levels in children?

Background: Vitamin B 12 (B 12 ) is an essential nutrient for DNA synthesis and cell metabolism. While B 12 deficiency has been extensively studied, the importance of elevated B 12 is under investigation. High levels are described in adults with malignancies and many other conditions. Limited and conflicting data exists pertaining to children with elevated levels. Methods: A single institution retrospective study was conducted. Patients younger than 18 years with high B 12 levels during the period of 2010-2018 were included. Patients with a history of or concurrent B 12 therapy were excluded. B 12 levels, complete blood cell counts, concurrent, prior and future diagnoses were collected. Results: A total of 384 patients with high B 12 levels were identified. An indication for obtaining a B 12 level was documented for 296 patients (77.1%) with most common reasons being fatigue (n = 36 , 12.2%), failure to thrive (n = 32, 10.8%) and anemia (n = 25, 8.4%). Seven indications, (2.4%) were obtained as follow-up of a previous malignancy. Within the 5 year follow up 47.8% of patients (n=142) had documentation of future diagnoses. The top 3 subspecialties with future diagnoses were psychiatry (n=53, 23.0%), gastroenterology (n=32, 13.9%) and neurology (n=26, 11.3%). Only one patient developed an oncologic diagnosis, Langerhans Cell Histiocytosis. Conclusion: Our study found no association of elevated B 12 with pediatric malignancies. However, we highlight a possible link between elevated B 12 and neuropsychiatric and gastroenterological processes. More studies are needed to further delineate the importance of elevated B 12 in the pediatric population.