Umbilical cord blood as a substitute for neonatal blood in measuring serum albumin and immunoglobulin G levels.

Objectives: In this study, we investigated the clinical feasibility of using umbilical cord blood as an alternative to neonatal blood for measuring serum albumin and immunoglobulin G (IgG) levels in newborns, including preterm newborns.

Methods: Serum levels of albumin and IgG were measured in cord and neonatal blood from singleton newborns. We analyzed correlations and systematic errors between cord and neonatal blood measurements, stratifying the results for very preterm newborns (VPNs) born at a gestational age of less than 32 weeks and non-VPNs born at a gestational age of 32 weeks or later.

Results: Among all 494 newborns (78 VPNs and 416 non-VPNs), serum albumin and IgG levels were determined for 95.7% and 88.7% of them, respectively. Strong correlations between cord and neonatal blood were observed for the serum albumin and IgG levels (rs = 0.864 and 0.966, respectively). Moreover, the measurement errors between cord and neonatal blood were small for all newborns (0.2 g/dL and 65 mg/dL, respectively). These findings were consistent with both VPNs and non-VPNs.

Conclusions: Umbilical cord blood is a suitable substitute for neonatal blood in measuring serum albumin and IgG levels in newborns, even in premature newborns.