Oxidative Challenge and Glucose-6-Phosphate Dehydrogenase Activity of Preterm and Term Neonatal Red Blood Cells

Abstract

Background: Recent studies suggest that a low antioxidant level in preterm infants may predispose them to increased oxidative stress and results in hyperbilirubinemia, whereas glucose-6-phosphate dehydrogenase (G6PD) activity was found to be higher in preterm infants than in term infants. Objectives: To evaluate (1) the oxidative effect of α-naphthol on preterm and term red blood cells, and (2) the relationship between G6PD activity and the gestational age of these infants. Methods: G6PD activities were determined in preterm and term infants by a standard diagnostic method. Whole blood samples were incubated with α-naphthol for 2 h and their pre- and post-challenged reduced glutathione (GSH) levels were quantified. Results: The mean G6PD activity in preterm infants (n = 113; 13.52 ± 0.19 U/g Hb; gestational age 30.67 ± 0.28 weeks) was significantly higher than that in term infants (n = 100; 12.36 ± 0.16 U/g Hb; gestational age 39.82 ± 0.14 weeks; p < 0.001). A significantly negative correlation was demonstrated between gestational age and G6PD activity (r = –0.34, p < 0.001). GSH levels of preterm and term subjects were similar at baseline, but were significantly decreased upon challenge with α-naphthol (p < 0.001). The percentage reduction in GSH levels was similar in the various gestational age groups. Conclusions: Our data show that G6PD activities had a negative correlation with gestational age of G6PD-normal infants. The similar response of preterm and term erythrocytes to an α-naphthol challenge indicates the manifestation of an active anti-oxidative pathway mediated by cellular GSH.

Lower reference limits of quantitative cord glucose-6-phosphate dehydrogenase estimated from healthy term neonates according to the clinical and laboratory standards institute guidelines: a cross sectional retrospective study

“…The G6PD values exhibited a normal distribution in the study by Boo et al but a non-normal distribution in the study by Fok et al [7,8]. The fact that only full-term neonates were included in both the present study and that by Boo et al might explain the normal distribution in those populations, while the inclusion of both preterm and term neonates in the study by Fok et al might account for the non-normal distribution, as G6PD activity has been shown to vary with gestational age (Table 3) [15,36,37]. Some researchers based their LRL and LDL estimations on the mean without addressing normal distribution testing [13].…”

“…Consequently, we suggested the parametric LRL of the combined gender group (11.0 U/g Hg) as the LRL for cord G6PD of term neonates. Future studies on the LRLs for preterm neonates using the IFCC-CLSI are warranted as G6PD activity has been shown to vary across gestational age categories [15,36,37]. …”

“…At KAH, birth notices that include the full name of both parents are issued upon home discharges and copies of these birth notices are stored in hard and electronic medical records of neonates. We selected only full-term neonates as we did not expect to have an adequate number of preterm neonates of the reference sample group during the study period and as G6PD values have been shown to be higher in preterm neonates <34 weeks of gestation [15,36,37]. Gestational age was calculated according to the best obstetric estimate at KAH based on the first or second trimester obstetric ultrasound and/or the last menstrual period, and on the Ballard score when the best obstetric estimate was uncertain [38,39].…”

Screening for glucose-6-phosphate dehydrogenase deficiency in neonates: a comparison between cord and peripheral blood samples

“…transcription) [12–16]. Other possibilities are increased erythropoiesis resulting in normoblastemia, reticulocytosis, or possible other characteristics peculiar to fetal and neonatal erythrocyte metabolism [15, 17]. Cappellini and colleagues cite this as a diagnostic issue among neonates which could lead to false negative results [17].…”