The effect of blood gas and Apgar score on cord blood cardiac Troponin I.

OBJECTIVES The aims of this study were to (a) establish a reference range for cardiac troponin I (cTnI) in the cord blood of healthy infants, and (b) investigate the effect of Apgar score, cord blood gas, gestational age, and creatine kinase (CK) and creatine kinase MB (CK-MB) fraction levels on cord blood cTnI levels. METHODS 112 perinatal hypoxic and 84 control newborns without perinatal hypoxia were enrolled in this study. Cord blood samples were collected from the babies for arterial blood gas analysis, cTnI, CK and CK-MB measurements. Gestational age, birth weight, sex, Apgar score and history of fetal distress were recorded. Hypoxic ischemic encephalopathy (HIE) group, hypoxic but without HIE group and control groups were identified according to clinical observations during the first 72 h in the newborn unit. RESULTS HIE and perinatal hypoxic without HIE groups had a significantly higher cord blood cTnI level according to the control group (1.8 ng/mL (0-13), 0 ng/ml (0-1.1) and 0 ng/ml (0-0.3) respectively). Cord blood cTnI level did not have a correlation with birth weight and gestational age (r = -0.02, p > 0.05 and r = 0.08, p > 0.05 respectively). Cord blood cTnI level also had a negative correlation with pH, bicarbonate, base deficit, and Apgar score (r = -0.40, p < 0.001; r = -0.39 p < 0.001; r = -0.45 p < 0.001; r = -0.41, p < 0.001) respectively). Cord blood cTnI level showed a positive correlation with CK and CK-MB levels (r = 0.45, p < 0.001 and r = 0.37, p < 0.001 respectively). Receiver operator curve analysis revealed that the most sensitive factor for prediction of perinatal hypoxia is cord cTnI value [area under curve = 0.929]. The optimal cut-off value of cord cTnI was 0.35 ng/ml for hypoxia. CONCLUSION cTnI levels in the cord blood are not affected by gestational age and birth weight. cTnI together with CK and CK-MB has been found to be elevated in hypoxic infants compared to normal infants. Therefore cTnI may be an indicator for perinatal hypoxia in neonates.