Early clinical and laboratory findings associated with mortality during continuous renal replacement therapy in neonates

Abstract

Objective: The aim of this study was to evaluate the demographic and clinical characteristics, short-term outcomes, and early clinical and laboratory indicators associated with mortality in neonates receiving continuous renal replacement therapy (CRRT) in a tertiary neonatal intensive care unit. Materials and Methods: This retrospective observational study included neonates younger than 28 days of postnatal age who received CRRT for at least 24 hours between October 1, 2019, and November 30, 2025. Patients were grouped according to in-hospital outcomes as survivors and non-survivors. Demographic, clinical, and laboratory variables were compared between the groups. Continuous variables with non-normal distributions were expressed as medians (IQR) and compared using the Mann–Whitney U test. Categorical variables were compared using the chi-square test or Fisher’s exact test, as appropriate. Given the limited sample size, the analyses were considered exploratory. Results: A total of 13 neonates were included. The median gestational age was 38 weeks and the median birth weight was 2930 g. Nine patients (69.2%) died during hospitalization, whereas four (30.8%) were discharged. In the mortality group, the serum calcium level at 12 h was lower than that in survivors (8.50 [7.40–9.00] vs. 9.65 [9.13–10.4], p=0.044). Lactate levels were higher in the mortality group at both  hour 12 (4.00 [4.00–11.0] vs 2.95 [2.67–3.15], p=0.035) and hour 24 (4.40 [3.60–13.0] vs 2.40 [1.75–3.05], p=0.035). Baseline kidney function tests and most pre-CRRT biochemical parameters were similar between the groups. Conclusion: In this single-center neonatal CRRT cohort, mortality was high. Lower total calcium at hour 12 and higher lactate levels at hours 12 and 24 were associated with mortality. These findings may reflect persistent physiological instability during the early phase of CRRT. However, because of the small sample size, retrospective design, and absence of multivariable adjustment, these associations should be interpreted as exploratory and hypothesis-generating rather than independent predictors of mortality.