Influence of Vitamin B12 Deficiency on Autonomic Nervous System Activity in Children

: Vitamin B12 has an important role in neuronal development of children. Autonomic nervous dysfunction which can be hidden by compensating mechanisms also accompanies vitamin B12 deficiency. However, in children, there is still limited data about this effect of vitamin B12 deficiency. The aim of this study was to evaluate the autonomic activity in vitamin B12 deficient children by analyzing the heart rate variability (HRV) with Holter monitoring. HRV parameters of 37 children who were diagnosed with vitamin B12 deficiency were compared those of 25 age and sex matched healthy controls. All of the heart rate variability parameters (time-domain and frequency-domain) were reduced in the vitamin B12 deficient group compared with controls. The search for factors modifying heart rate variability yielded that serum vitamin B12 level was significantly effective on both time-domain and frequency-domain HRV parameters. A positive correlation was also found between vitamin B12 levels and the mean of the 5 minute RR interval standard deviations (SDNNi), the square root of the mean of the squared differences of two consecutive RR intervals (RMSSD), low-frequency power (LF) parameters (P < 0.05, r: 0.285, 0.262, 0.246, respectively). In conclusion, vitamin B12 deficiency can cause autonomic dysfunction in children.