Value of twelfth hour bilirubin level in predicting significant hyperbilirubinemia in preterm infants

Abstract

Background: As hyperbilirubinemia is a significant cause of brain injury, it is important to predict the cases who are at risk. Data for preterm infants are scarce. The aim of this study is to predict significant hyperbilirubinemia in preterm infants by measuring capillary bilirubin at 12th hour of life.

Methods: One hundred and fifty neonates born ≤ 35 weeks were included in the study. They were categorized into two groups according to their birth weights (group 1: 1,000 - 1,499 g; group 2: 1,500 - 2,000 g). Their bilirubin levels were measured at 12th hour and daily thereafter for 5 days. Risk nomograms were generated based on their bilirubin measurements and postnatal ages. On the age-specific percentile-based nomogram, the zone above the 90th percentile was determined as high risk and those below the fifth percentile as low risk. Infants who had bilirubin levels over the limits defined according to their postnatal ages and birth weights were accepted to have significant hyperbilirubinemia and received phototherapy and predictive value of the 12th hour bilirubin was asssessed.

Results: Fifty-four of 57 infants (94.7%) in group 1 and 75/93 infants (80.7%) in group 2 received phototherapy. Capillary bilirubin levels of 3.55 mg/dL and 4.55 mg/dL for group 1 and group 2 measured at the 12th hour of life had the highest sensitivity, negative and positive predictive value to predict the neonates who will develop significant hyperbilirubinemia.

Conclusion: Bilirubin levels of preterm infants should be monitored closely. More attention should be paid to the ones who had 12th hour bilirubin level above the cutoff values.

Keywords: Hyperbilirubinemia; Neonate; Phototherapy; Preterm.

Figure 1

Receiver operating characteristic curve analysis in group 1 (birth weight: 1,000 - 1,499 g) (cutoff: 3.55 mg/dL).

Figure 2

Receiver operating characteristic curve analysis in group 2 (birth weight: 1,500 - 2,000 g) (cutoff: 4.55 mg/dL).

Figure 3

Risk nomogram prepared from total capillary bilirubin levels obtained in the first 5 postnatal days of the infants whose birth weights ranged between 1,000 and 2,000 g (150 patients). HRZ: high risk zone (> 95%); HIRZ: high intermediate risk zone (60-95%); IRZ: intermediate risk zone (30-60%); LIRZ: low intermediate risk zone (5-30%); LRZ: low risk zone (< 5%).