Low plasma magnesium is associated with impaired brain metabolism in neonates with hypoxic-ischaemic encephalopathy

Aim: To determine the association between lowest plasma magnesium concentration and brain metabolism, and whether magnetic resonance imaging brain injury patterns moderated the association in hypoxic-ischemic encephalopathy. Methods: In 131 early (day-of-life 3) and 65 late (day-of-life 10) scans of term encephalopathic infants born between 2004 and 2012, we examined the association of lowest plasma magnesium (until day-of-life 3) on basal ganglia and white matter peak metabolite ratios on magnetic resonance spectroscopy independent of covariates, stratified by the predominant patterns of injury (normal, basal nuclei/total, watershed, multifocal) using multiple linear regression. Results: Lowest plasma magnesium was associated with lower white matter N-acetyl-aspartate/choline in the multifocal pattern on early scan (regression-coefficient, β: 0.13; 95% CI: 0.04, 0.22) and in the basal nuclei/total pattern on late scan (β: 0.08; 95% CI: 0.02, 0.15), and was negatively associated with basal ganglia lactate/N-acetyl-aspartate (β: −0.16; 95% CI: −0.05, −0.28) and lactate/choline (β: −0.1; 95% CI: −0.03, −0.17) ratio in the basal nuclei/total pattern on late scan independent of hypomagnesaemia correction, cooling and postmenstrual age at scan. Lowest plasma magnesium was not associated with metabolite ratios in other brain injury patterns. Conclusion: In infants with hypoxic-ischaemic encephalopathy, predominant patterns of brain injury moderated the association between lowest plasma magnesium in the first three days of life and impaired brain metabolism.