Erythrocyte Enzyme Activities in Cord Blood of Extremely Low-Birth-Weight Infants

To investigate the features of erythrocyte metabolism in extremely immature infants, we assayed 21 enzyme activities and glutathione level in cord erythrocytes from 28 extremely low-birth-weight infants (ELBWI; defined as birth weight <1,000 g). The results were compared with those from normal adults and non-neonatal reticulocyte-rich controls. Statistical analysis revealed that activities of six enzymes (glucosephosphate isomerase, phosphoglycerate kinase, monophosphoglycerate mutase, enolase, glucose-6-phosphate dehydrogenase (GGPD), and glutathione reductase) were significantly higher, and those of eight other enzymes (phosphofructokinase, G-phosphogluconate dehydrogenase (6PGD), glutathione peroxidase, adenylate kinase, adenosine deaminase, acetyt-cholinesterase, NADH methemoglobin reductase, and catalase) were lower in ELBWI taking their marked reticulocytosis into consideration. The 6PGD/G6PD ratio, which is consistently unchanged under various physiological and pathological conditions, was markedly reAduced in ELBWI. Our results support the previous reports that neonatal erythrocytes have a unique metabolic pattern which Is different from that of adult erythrocytes, and also suggest that the 6PGD/G6PD ratio might be an index for the developmental immaturity of fetal erythrocytes. This is the first report describing the pattern of erythrocyte enzyme activities in ELBWI. Am. J. Hematol 62:88-92, 1999.