354 - Prolonged unbound bilirubinemia in extremely premature infants

Poster Number: 354
Publication Number: 354.123

Sota Iwatani, Hyogo Prefectural Kobe Children's Hospital, Kobe, Hyogo, Japan; Kentaro Hirayama, Wakayama Medical University Hospital, Wakayama, Wakayama, Japan; Shinji Hagimoto, Hyogo Prefectural Kobe Children's Hospital, Kobe, Hyogo, Japan; Ayako Izumi, Hyogo Prefectural Kobe Children's Hospital, Kobe, Hyogo, Japan; Dai Kataoka, Hyogo Prefectural Kobe Children`s Hospital, Kobe, Hyogo, Japan; Seiji Yoshimoto, Hyogo Prefectural Kobe Children's Hospital, Kobe, Hyogo, Japan

Background: Despite advances in perinatal and neonatal intensive care, cases of preterm infants with bilirubin encephalopathy (pBE) are still being reported, especially in those born extremely premature. Elevated albumin-free or unbound bilirubin (UB) levels beyond the 1st week of life have been associated with pBE development, however, the mechanism(s) that induce prolonged unbound bilirubinemia has remained largely unknown.

Objective: To investigate the mechanisms involved in prolonged unbound bilirubinemia in preterm infants.

Design/Methods: For this retrospective study, 22 preterm infants born between 28 to 31 wks’ gestational age (GA) (PI group) and 21 extremely preterm infants born between at 22 to 27 wks’ GA (EPI group) were enrolled. Total serum bilirubin (TB), UB, and albumin (Alb) levels were prospectively measured once a week. Bilirubin/Alb (B/A) binding was assessed by calculations of TB/Alb ratio, UB/TB ratio, and Ka. Data are presented as mean±SD.

Results: Serum UB levels were significantly decreased from day 7 to 28 (0.44±0.13 to 0.22±0.16 μg/dL, respectively, p < 0.001) in the PI group. in contrast to that found in the EPI group (from 0.37±0.12 to 0.34±0.29 μg/dL, respectively) with significant increases in serum Alb levels (from 2.4±0.3 to 2.8±0.3 g/dL). On day 28, TB/Alb ratios were comparable between the two groups. However, the EPI group had relatively higher UB/TB ratios compared with the PI group (0.064±0.024 vs. 0.035±0.013, p < 0.001), and lower Ka values (55.0±25.3 L/μmol) were further confirmed in the EPI group.Conclusion(s): In extremely premature infants, serum UB levels are not decreased during the first 4 weeks of life, but lower B/A binding can explain the prolonged unbound bilirubinemia observed in these extremely premature infants.
Table 1. Comparison of the serum TB, UB, and Alb levels, TB/Alb ratios, UB/TB ratios, and calculated Ka values on Day 28 between two gestational groups.