Magnesium is found almost entirely in the intracellular compartment. The small serum component gives a poor representation of the active, physiologic state of the metal. This state is assessed much better by measuring ionized magnesium in the serum, This study was undertaken to investigate the plasma levels of ionized Mg in neonatal nonhemolytic hyperbilirubinemia by comparing the newborns with and without significant hyperbilirubinemia, Forty full term neonates their gestational ages ranged from 37 to 42 weeks were presented with jaundice(study group) and another 40 full term neonates without jaundice (control group) were included in the study both groups were subjected to complete clinical examination, laboratory investigations, CBC, serum calcium, phosphorus, serum bilirubin and ionized Magnesium. The results showed that Serum bilirubin was significantly higher in study group compared to control group (P value <0.001). Also Serum ionized Mg was significantly higher in study group compared to control group (P value = 0.04). Positive correlation between the mean serum bilirubin and the plasma ionized Mg levels. Conclusion; increase in plasma IMg may be due to extracellular movement of Mg, a principally intracellular ion, resulting from generalized cellular injury including neurons and erythrocytes. This increase has neuroprotective role against emerging toxicity risk of increasing serum bilirubin levels. [Abdel hakeem Abdel mohsen, Mohammed F Afify, Emad Allam and Hedaya Abdelkarem. Role of Magnesium ion in neonatal jaundice. Life Sci J 2012;9(3):2274-2278] (ISSN: 1097-8135). http://www.lifesciencesite.com. 405
