eGFR values and selected renal urine biomarkers in preterm neonates with uncomplicated clinical course.

BACKGROUND: Diagnosing acute kidney injury (AKI) in preterm newborns, who are particularly susceptible to renal damage, is a serious challenge as there is no definite consensus about the diagnostic criteria. OBJECTIVES: The objective of this study was to measure the values for selected urinary biomarkers and estimated glomerular filtration rate (eGFR) among a population of preterm infants with uncomplicated clinical course as well as to determine whether these markers depend on birth weight (BW), gestational age (GA), postnatal age (PNA), or gender. MATERIAL AND METHODS: The prospective study was carried out in neonatal intensive care unit (NICU). The evaluation included 57 children that were divided into 3 categories according to BW: low birth weight (LBW) - 1501-2500 g (22 infants); very low birth weight (VLBW) - 1000-1500 g (25 infants); and extremely low birth weight (ELBW) - 750-999 g (10 infants). Urine samples were collected daily between the 4th and 28th day of life for measurements of creatinine (Cr), neutrophil gelatinase-associated lipocalin (NGAL), osteopontin (OPN), and human kidney injury molecule 1 (hKIM1). RESULTS: The values of the 3 urine tubular biomarkers, serum creatinine and eGFR were taken in substantially healthy preterm infants with normal kidney function at 4 time intervals during the neonatal period. Their correlations were determined and a multivariable regression analysis was carried out with respect to BW, GA, PNA, and gender. Trends of the studied markers in terms of PNA and BW were also assessed with the Jonckheere-Terpstra test. CONCLUSIONS: Glomerular and tubular function in preterm neonates during the 1st month of life is significantly influenced by BW, GA, PNA, and gender.