Neonatal bilirubin production-conjugation imbalance: effect of glucose-6-phosphate dehydrogenase deficiency and borderline prematurity
- 1Department of Neonatology, Shaare Zedek Medical Center, Jerusalem, Israel
- 2Faculty of Medicine, Hebrew University, Jerusalem, Israel
- 3Faculty of Health Sciences, Ben Gurion University of the Negev, Be’er Sheva, Israel
- 4Department of Internal Medicine, University of Padua, Florence, Italy
- 5Department of Neonatology, University of Florence, Florence, Italy
- 6Division of Neonatal and Developmental Medicine, Department of Pediatrics, Stanford University Medical Center, Stanford, CA, USA
- Correspondence to:
Department of Neonatology, Shaare Zedek Medical Center, PO Box 3235, Jerusalem 91031, Israel;
- Accepted 7 October 2004
Objective: To evaluate relations between production and conjugation of bilirubin in the pathophysiology of jaundice in glucose-6-phosophate dehydrogenase (G6PD) deficient neonates.
Methods: Term and borderline premature (35–37 weeks gestational age), healthy, male, G6PD deficient neonates were studied close to the beginning of the 3rd day. Blood carboxyhaemogobin corrected for inspired CO (COHbc; an index of bilirubin production) and serum total conjugated bilirubin (TCB; a reflection of bilirubin conjugation) were measured in simultaneously drawn blood samples by gas chromatography and reverse phase high performance liquid chromatography respectively. A bilirubin production-conjugation index comprising COHbc/TCB was determined; a high index reflects imbalance between the bilirubin production and conjugation processes. COHbc and TCB individually and the production-conjugation index were studied in relation to serum total bilirubin (STB) concentration.
Results: Fifty one G6PD deficient neonates were sampled at 51 (8) hours. COHbc values did not correlate with STB (r = 0.22, p = 0.15). TCB did correlate inversely with STB (r = −0.42, p = 0.004), and there was a positive correlation between the production-conjugation index and STB (r = 0.45, p = 0.002). The production-conjugation index (median (interquartile range)) was higher in the premature (n = 8) than term neonates (2.31 (2.12–3.08) v 1.05 (0.53–1.81), p = 0.003). This difference was the result of changes in TCB.
Conclusions: The data show that jaundice in G6PD deficient neonates is the result of an imbalance between production and conjugation of bilirubin with a tendency for inefficient bilirubin conjugation over increased haemolysis in its pathogenesis. Borderline premature infants are at especial risk of bilirubin production-conjugation imbalance.
- COHb, carboxyhaemoglobin
- COHbc, COHb corrected for inspired (room air) CO
- G6PD, glucose-6-phosphate dehydrogenase
- HPLC, high performance liquid chromatography
- STB, serum total bilirubin
- TCB, total conjugated bilirubin
↵* Present address: Clinical Chemistry Laboratory, Ospedale Pediatrico Bambino Gesu, Piazza Sant’ Onofrio 4, 00165 Rome, Italy
Competing interests: none declared
Presented in part at the Pediatric Academic Societies’ Annual Meeting, Seattle, WA, USA, 3–6 May, 2003.