Evaluation of total oxidant status/total antioxidant capacity and DNA damage in neonates with high lactate levels in umbilical cord blood gases

The relationship between elevated lactate levels, oxidative stress (OS) and DNA damage in neonates remains unclear; however, neonates with high lactate levels in umbilical cord gases may exhibit increased OS and DNA damage, thus serving as an indirect indicator of OS and DNA damage. The present study evaluated the relationship between elevated umbilical cord blood lactate levels, OS and DNA damage in term neonates. The present prospective, single-center study included 61 term newborns, categorized into a study group (n=38) with cord blood lactate levels of ≥5 mmol/l, and a control group (n=23) with lactate levels of <5 mmol/l. Blood samples of the study and control groups were obtained within the first 12 h for measurements of total oxidant status (TOS), total antioxidant capacity (TAC) and DNA damage. Second samples and measurements were obtained at 72-96 h after lactate levels fell to <5 mmol/l in the study group and samples for the control group were also obtained at postnatal 72-96 h for TOS and TAC measurements. Results in the first 12 h were referred to as TOS1/TAC1, while results at 72-96 h were referred to as TOS2/TAC2. The most accurate lactate cut-off for predicting pH ≤7.2 was 5.005 mmol/l (sensitivity, 92.9%; specificity, 48.9%). TOS1, TOS2, TAC1 and TAC2 levels were significantly higher in the study group (P<0.001). DNA damage was also higher in neonates with elevated lactate levels (P=0.01). Furthermore, lactate was negatively correlated with pH and base excess, and was positively correlated with DNA damage, TOS2 and TAC. In conclusion, these findings indicated that newborns with high umbilical cord lactate levels experience increased OS and DNA damage, even after lactate normalization. Therefore, lactate may serve as an indirect indicator of neonatal OS, warranting further investigation into its long-term implications.