A study of cord blood alkaline phosphatase as a predictor of neonatal hyperbilirubinemia in a tertiary hospital

Abstract Background: Neonatal hyperbilirubinemia remains a significant concern in neonatal care, affecting newborn health and requiring early identification for timely intervention. Neonatal jaundice, a common condition observed in approximately 80% of preterm and 60% of full-term infants, necessitates the exploration of reliable predictive markers for hyperbilirubinemia. Aims and Objectives: This study aims (i) to evaluate whether cord blood alkaline phosphatase (ALP) levels can be an early diagnostic marker and predictor of hyperbilirubinemia in full-term newborns and (ii) to assess the incidence and identify the etiological risk factors associated with neonatal hyperbilirubinemia occurring after 72 h of birth. Materials and Methods: This prospective observational study was conducted over 1.5 years at Dr. DY Patil Medical College, Hospital, and Research Centre in Navi Mumbai. The study aimed to assess the potential role of cord blood ALP levels in predicting hyperbilirubinemia among full-term neonates. Cord blood ALP levels were measured at birth, and serum bilirubin levels were subsequently assessed at 72 h of life. Results: Among the 200 neonates included in the study, 122 had cord blood ALP levels exceeding 314 IU/L, while 78 had levels below this threshold. During follow-up, hyperbilirubinemia (serum bilirubin >13 mg/dL at 72 h post-birth) was observed in 15 neonates with high ALP levels, compared with only two cases in the low ALP group. About 61% of newborns had cord ALP levels above 314 IU/L, while 39% were below this cutoff. The mean cord ALP level recorded was 315.7 IU/L, providing valuable predictive insights. ALP showed high sensitivity (88.2%) but low specificity (41.5%) for predicting hyperbilirubinemia, with a high negative predictive value (NPV) (97.4%) but low positive predictive value (PPV) (12.3%). The accuracy of 45.5% underscores the importance of early assessment using cord ALP levels. Additionally, the receiver operating characteristic (ROC) curve analysis showed an area under the curve of 0.64, reinforcing the correlation between cord blood ALP levels and subsequent serum bilirubin levels. Conclusion: This study establishes a significant association between cord blood ALP levels and serum bilirubin levels at 72 h of life, demonstrating high sensitivity but low specificity. These findings suggest that cord blood ALP levels could serve as an effective early predictor of neonatal hyperbilirubinemia, emphasizing the importance of ALP estimation in the early diagnosis and management of this condition.