Electrolyte Changes in Neonates Receiving Phototherapy for Physiological Hyperbilirubinemia: A Prospective Observational Study from a Tertiary Care Centre in Bihar

Abstract

Background: Phototherapy is the first-line treatment for neonatal hyperbilirubinemia, but its influence on serum electrolyte homeostasis remains incompletely characterised, particularly in resource-limited settings. This study evaluated alterations in serum bilirubin and electrolytes in neonates receiving phototherapy for physiological hyperbilirubinemia. Methods: In this prospective observational study, 120 neonates with physiological or breastfeeding hyperbilirubinemia admitted to the Special Newborn Care Unit (SNCU), Darbhanga Medical College and Hospital, were enrolled. Baseline values (control group, n = 60) and post-phototherapy values obtained after 48 hours of treatment (study group, n = 60) were compared. Serum bilirubin, calcium, magnesium, sodium, potassium, and chloride were measured before and after therapy. Subgroup analyses were performed by gestational age and by phototherapy duration (24, 30, 36, and 48 hours). Results: The groups were comparable in age (5.47 ± 1.10 vs 5.57 ± 1.20 days; p = 0.634), sex distribution (p = 1.00), gestational age (p = 0.315), birth weight (p = 0.203), and jaundice type (p = 0.465). Phototherapy duration was significantly longer in the study group (39.23 ± 10.19 vs 28.63 ± 6.20 hours; p = 0.0001). Serum bilirubin was significantly higher after therapy (14.41 ± 2.49 vs 10.96 ± 1.67 mg/dL; p = 0.0001), whereas serum calcium declined significantly (8.34 ± 0.73 vs 9.22 ± 0.68 mg/dL; p = 0.0001). Hypocalcemia developed in 48% of treated neonates (p = 0.0001). Magnesium, sodium, potassium, and chloride remained largely unchanged. Conclusions: Phototherapy was associated with a significant fall in serum calcium, confirming hypocalcemia as the most consistent metabolic complication, while other electrolytes remained stable. Routine calcium monitoring during phototherapy is recommended to ensure early detection and timely correction, particularly in settings where laboratory surveillance is limited.

Keywords: Neonatal hyperbilirubinemia; Phototherapy; Hypocalcemia; Electrolytes; Calcium; Magnesium; Sodium; Potassium; Chloride; SNCU.