Low adjusted serum ionized calcium concentration shortly after birth predicts poor outcome in neonatal hypoxic–ischemic encephalopathy

Abstract

Hypoxic-ischemic reperfusion injury causes either necrosis or apoptosis, and the influx of ionized calcium into cells is the major cause of both types of cell death. The aim of this study was to investigate whether or not the serum ionized calcium concentration in neonates with hypoxic-ischemic encephalopathy (HIE) could be used to predict their outcome. Serum samples were obtained shortly after birth from 20 HIE neonates who had not urinated or received treatment with calcium. Serum ionized calcium concentrations were adjusted for pH using a correction formula. Twelve neonates without any disease were selected as a control. The results were compared between nine HIE neonates who made a full recovery, 11 who died or had neurologic deficits, and 12 normal neonates. Considered together, the two HIE groups had lower serum ionized calcium concentrations (1.05 +/- 0.10 mmol/L) than the control group (1.22 +/- 0.07 mmol/L; P < 0.0001). Moreover, serum ionized calcium concentrations in the group with the poor outcome (0.99 +/- 0.07 mmol/L) were lower than those in the group that made a full recovery (1.13 +/- 0.06 mmol/L; P=0.0016). The serum ionized calcium concentrations shortly after birth were significantly lower in neonates with HIE who had a poor outcome. Low concentrations may reflect multiple organ damage, particularly involving the brain.