Reference values for nucleated red blood cells and serum lactate in very and extremely low birth weight infants in the first week of life

Abstract

Study purpose: To provide reference values for nucleated red blood cells and serum lactate concentrations in very and extremely low birth weight (VLBW/ELBW) infants in the first week of life.

Patients and methods: Retrospective data analysis of serial, daily measurements of NRBC counts and serum lactate during the first 6days of life in VLBW and ELBW infants.

Results: In total, 250 infants<1500g were included in this study. Intrauterine growth retardation (IUGR) was seen in 87 (34.8%) patients. Gestational age (GA) ranged from 23 to 35weeks (mean 29.0weeks) and birth weight (BW) was 320-1499g (mean 1047.9g). During hospital stay, 55 (22%) patients developed IVH and 55 children (22%) BPD. PVL was seen in 12 (4.8%) cases, ROP in 93 (37.2%) and NEC in only 1 (0.4%) patient. NRBC counts as well as serum lactate concentrations depended significantly on birth weight (p<0.01) and presence respectively absence of IUGR (p<0.01). Both NRBC counts and serum lactate concentrations declined constantly during the 6-day period (p<0.01), and both were highly inter-correlated (p<0.01).

Conclusions: This is one of only a very few studies that systematically and serially evaluated both NRBC counts and serum lactate concentration in VLBW and ELBW infants in the first 6days of life. Both parameters were significantly dependent on birth weight and the presence of IUGR. Moreover, a significant correlation between NRBC counts and serum lactate concentrations in this early period of life could be demonstrated. In future studies, the role of these readily available biomarkers in predicting important neonatal outcome parameters needs to be evaluated in a prospective manner.

Keywords: ELBW infants; Nucleated red blood cells; Serum lactate; VLBW infants.