[Hyperbilirubinemia in full-term newborns. Predictive factors].

OBJECTIVE: Nowadays economical criteria lead to early maternal hospital discharge, even before 48 hours after labor, producing an increase in neonatal readmissions for hyperbilirubinemia. We tried to predict the healthy term newborns that may develop a significant hyperbilirubinemia (> or = 17 mg/dl in the first 4 days of life).

METHODS: Bilirubin in umbilical cord blood, transcutaneous measurements of bilirubin at 24, 48 and between 60 and 96 hours of life and bilirubin in blood obtained from heel-sticks at 96 hours was analyzed in 610 newborns. Moreover, serum bilirubin was determined at the same time-points in 169 newborns submitted to blood extractions for different reasons. The transcutaneous bilirubinometer used was a Minolta/Air-Shields JM-102.

RESULTS: A significant hyperbilirubinemia was present in 2.95% of the newborns. The correlation between serum and transcutaneous bilirubin was high (r = 0.92; p < 0.0001). Umbilical cord blood bilirubin with a cut-off point of 2.2 mg/dl was not an useful predictor of neonatal jaundice. At 24 and 48 hours of life serum bilirubin levels > or = 6 mg/dl and > or = 9 mg/dl, respectively, predicted a subsequent hyperbilirubinemia with a sensitivity of 100% at both time-points, specificity of 47.5% and 64.3%, positive predictive value of 7.3% and 16.4%, respectively, and a negative predictive value of 100% for both. Transcutaneous measurement at 48 hours with a cut-off point of 13 (equivalent to a bilirubinemia of 9 mg/dl) predicts hyperbilirubinemia with a sensitivity of 94.4%, specificity of 51.7%, positive predictive value of 6.0% and negative predictive value of 99.6%.

CONCLUSIONS: If the newborn presents a bilirubinemia > or = 6 mg/dl at 24 hours and > or = 9 mg/dl or a transcutaneous measurement > or = 13 at 48 hours a new bilirubin measurement must be performed between 48 and 72 hours of life.