Measurement of the urinary lactate/creatinine ratio for early diagnosis of the hypoxic-ischemic encephalopathy in newborns

Objective: Hypoxic ischemic encephalopathy (HIE) is a major cause of permanent neurological disabilities. Perinatal asphyxia may induce neonatal mortality after birth or neurological impairment among survivors. There are no reliable methods for identifying infants at risk for this disorder.

Methods: We measured the ratio of lactate/creatinine (L/C) in urine by proton nuclear magnetic resonance spectroscopy within 6 and 24 hours after birth in 50 normal infants and 50 infants with asphyxia who developed hypoxic-ischemic encephalopathy. The study was performed from September 2006 to May 2007. For statistical analysis, the SPSS software was used. Group comparisons were performed with chi-square and t-test(1, 5).

Findings: L/C ratio was 3.3±2 among asphyxiated neonates in the first six hours after birth which was 11 folds greater than in normal neonates (0.3±0.08, P=0.0001). This ratio decreased to 1.5±0.55 for asphyxiated cases in the first 24 hours after birth, which was 5 folds greater than in control group (P=0.0001). Asphyxiated neonates were subdivided into Group A with mild asphyxia and L/C ratio 2.5±0.5; Group B with moderate asphyxia and L/C ratio 4.2±1.5; and Group C with severe asphyxia and L/C ratio 3.4±3.3. The severity of asphyxia correlated with the greater L/C ratio among our cases and was significant (P=0.0007). The sensitivity and specificity of L/C ratio in cut off point of 0.48, was 96.1% and 100% respectively.

Conclusion: Measurement of the urinary L/C ratio soon after birth maybe a promising tool to identify asphyxiated neonates and also to predict the severity of asphyxia.