Early Acute Kidney Injury in Preterm and Term Neonates: Incidence, Outcome, and Associated Clinical Features.

BACKGROUND

Critically ill neonates are at high risk of kidney injury, mainly in the first days of life. Acute kidney injury (AKI) may be underdiagnosed due to lack of a uniform definition. In addition, long-term renal follow-up is limited.

OBJECTIVE

To describe incidence, etiology, and outcome of neonates developing AKI within the first week after birth in a cohort of NICU-admitted neonates between 2008 and 2018. Renal function at discharge in infants with early AKI was assessed.

METHODS AND SUBJECTS: AKI was defined as an absolute serum Cr (sCr) value above 1.5 mg/dL (132 μmol/L) after the first 24 h or as stage 2-3 of the NIDDK neonatal definition. Clinical data and outcomes were collected from medical records and retrospectively analyzed.

RESULTS

From January 2008 to December 2018, a total of 9,376 infants were admitted to the NICU of Wilhelmina Children's Hospital/UMC Utrecht, of whom 139 were diagnosed with AKI during the first week after birth. In 72 term infants, the most common etiology was perinatal asphyxia (72.2%), followed by congenital kidney and urinary tract malformations (CAKUT) (8.3%), congenital heart disease (6.9%), and sepsis (2.8%). Associated conditions in 67 preterm infants were medical treatment of a hemodynamic significant PDA (27.2%), -CAKUT (21%), and birth asphyxia (19.4%). Among preterm neonates and neonates with perinatal asphyxia, AKI was mainly diagnosed by the sCr >1.5 mg/dL criterion. Renal function at discharge improved in 76 neonates with AKI associated with acquired conditions. Neonates with stage 3 AKI showed increased sCr values at discharge. Half of these were caused by congenital kidney malformations and evolved into chronic kidney disease (CKD) later in life. Neurodevelopmental outcome (NDO) at 2 years was favorable in 93% of surviving neonates with detailed follow-up.

CONCLUSION

During the first week after birth, AKI was seen in 1.5% of infants admitted to a level III NICU. Renal function at discharge had improved in most neonates with acquired AKI but not in infants diagnosed with stage 3 AKI. Long-term renal function needs further exploration, whereas NDO appears to be good.