The Prognostic Value of Serum Creatinine Dynamics in Neonates-A Retrospective Cohort Study

Background: Acute kidney injury (AKI) is common in neonates with increased mortality and longer hospitalization. Few studies have evaluated AKI outcomes in relation to serum creatinine dynamics in neonates from the first day of life. Methods: We performed an observational, retrospective, single-center study on newborns admitted to the "Louis Turcanu" Emergency County Hospital for Children between 2014 and 2022. The cohort comprised 1106 neonates with their serum creatinine values recorded on the first day of life and at least another measurement taken at between days 2 and 7. We evaluated the outcomes of serum creatinine trends in relation to mortality, hospitalization and progression to chronic kidney disease. Results: Overall, 23.4% (259) of babies had an ascending trend of serum creatinine and on day 1 had higher urea levels, lower hemoglobin and thrombocytes, lower serum proteins and higher degrees of inflammation compared to the ones with descending trends. An ascending serum creatinine level trend was associated with increased neonatal AKI (nAKI) risk in the first seven days of 12.93 times and an increased overall nAKI risk of 4.07 times. Ascending creatinine trends independently increased mortality in the entire cohort by 1.92 times and by 4.65 times in the subgroup of patients without AKI. In the crude analysis, an ascending creatinine trend increased the risk of chronic kidney disease by 8.74 times and, in an adjusted model, only nAKI was an independent risk factor (8.57 times). Conclusions: Neonates are a high-risk population with prolonged hospitalization regardless of serum creatinine trend. Our study emphasizes the importance of monitoring serum creatinine trends in at-risk newborns, especially those with ascending serum creatinine trends in the first week of life. Only the ascending serum creatinine trend was independently associated with an increased risk of nAKI development and mortality. nAKI is a risk factor for progression to chronic kidney disease.