Phototherapy Alters the Plasma Metabolite Profile in Infants Born Preterm with Hyperbilirubinemia

Objective: To investigate the effects of gestational age (GA) and phototherapy on the plasma metabolite profile of preterm infants with neonatal hyperbilirubinemia (NHB).

Study design: From a cohort of prospectively enrolled infants born preterm (n = 92), plasma samples of very preterm (VPT; GA, 28 + 0 to 31 + 6 weeks, n = 27) and moderate/late preterm (M/LPT; GA, 32 + 0 to 35 + 6 weeks, n = 33) infants requiring phototherapy for NHB were collected prior to the initiation of phototherapy and 24 hours after starting phototherapy. An additional sample was collected 48 hours after starting phototherapy in a randomly selected subset (n = 30; VPT n = 15; M/LPT n = 15). Metabolite profiles were determined using ultraperformance liquid chromatography tandem mass spectroscopy. Two-way ANCOVA was used to identify metabolites that differed between GA groups and timepoints after adjusting for total serum bilirubin levels (false discovery rate q-value < 0.05). Top impacted pathways were identified using pathway over-representation analysis.

Results: Phototherapy was initiated at lower total serum bilirubin (mean ± SD mg/dL) levels in VPT compared with M/LPT infants (7.3 ± 1.4 vs 9.9 ± 1.9, P < .01). We identified 664 metabolites that were significant for a phototherapy effect, 191 metabolites significant for GA, and 46 metabolites significant for GA × phototherapy interaction (false discovery rate q-value < 0.05). Longer duration phototherapy had a larger mean effect size (24 hours postphototherapy: d = 0.36; 48 hours postphototherapy: d = 0.43). Top pathways affected by phototherapy included membrane lipid metabolism, one-carbon metabolism, creatine biosynthesis, and oligodendrocyte differentiation.

Conclusion: Phototherapy alters the plasma metabolite profile more than GA in preterm infants with NHB, affecting pathways related to lipid and one-carbon metabolism, energy biosynthesis, and oligodendrocyte differentiation.