Case Report The effect of blood gas and Apgar score on cord blood cardiac Troponin I Gu ¨lcan Tu ¨rker, Kadir Babaog ˘lu, Can Duman, Ays ¸e S Go ¨kalp, Emine Zengin and Ays ¸e Engin Arısoy From the Department of Pediatrics and Biochemistry, Faculty of Medicine Kocaeli University, Kocaeli, Turkey 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 = 70.02, p 4 0.05 and r = 0.08, p 4 0.05 respectively). Cord blood cTnI level also had a negative correlation with pH, bicarbonate, base deficit, and Apgar score (r = 70.40, p 5 0.001; r = 70.39 p 5 0.001; r = 70.45 p 5 0.001; r = 70.41, p 5 0.001) respectively). Cord blood cTnI level showed a positive correlation with CK and CK-MB levels (r = 0.45, p 5 0.001 and r = 0.37, p 5 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. Key words: CORD BLOOD; CREATINE KINASE MB; GESTATIONAL AGE; BIRTH WEIGHT; TROPONIN I; PERINATAL HYPOXIA INTRODUCTION Cardiac troponin I (cTnI) has emerged as a biochemical marker for the detection of myocardial cell damage in acute coronary syndromes, largely replacing creatine kinase (CK) and creatine kinase MB (CK-MB) 1 . Poor correlation of cTnI and CK-MB was noted during the first year of life. Quivers et al. showed that preterm infants had a significantly higher cTnI level than term infants 2,3 . This differs from the results of Hirsch et al. who found that a significant elevation in cTnI in a pediatric intensive-care setting may be an indicator of poor outcome 4 . The purpose of this study is to offer an explanation for this discrepancy and to investigate the relation between elevated cTnI levels and cord pH, Apgar score and CK and CK-MB. The aims of this study were to (a) establish a reference range for cTnI in the cord blood of healthy infants, and (b) investigate levels of cord cTnI in hypoxic infants. Correspondence: G. Tu¨rker. Department of Pediatrics, Faculty of Medicine, Kocaeli University, 41900 Kocaeli, Turkey The Journal of Maternal–Fetal and Neonatal Medicine 2004;16:315–319 # 2004 Parthenon Publishing. A member of the Taylor & Francis Group DOI: 10.1080/14767050400017991 Received 07-01-04 Revised 10-04-04 Accepted 08-07-04