This is the first report of sKIM-1 and uKIM-1 levels in healthy full-term newborns during the first postnatal days. The data from healthy newborns may serve as the reference values for future studies in the youngest children.

Background: Intrauterine growth restriction (IUGR) is a poorly understood complication of pregnancy. It may be associated with various diseases in adulthood, such as hypertension, cardiovascular disease, insulin resistance, and end-stage renal disease. Objectives: The aim of this study was to check whether IUGR affects the function of renal tubules, as assessed by the tubular damage markers neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule 1 (KIM-1). Methods: The study included 126 term neonates. Thirty-eight newborns were the result of pregnancies complicated by IUGR. Eighty-eight healthy newborns were the result of normal pregnancies with no prenatal or perinatal complications. The concentrations of urinary NGAL and KIM-1 were determined with a commercially available ELISA kit and were normalized for urinary creatinine (Cr) concentration. Results: We found a significantly higher urinary concentration of NGAL and NGAL/Cr ratio in newborns from pregnancies complicated by IUGR when compared to the reference group. We found that female gender was associated with a higher concentration of urinary NGAL and also urinary NGAL/Cr. Conclusions: This is the first work that demonstrates that urinary NGAL concentration and urinary NGAL/Cr are significantly higher in infants that are small for gestational age than in appropriate-for-gestational-age infants. This might indicate subclinical kidney damage in newborns with IUGR.

Our findings showed that urine NGAL, but not serum levels, were significantly higher in girls than in boys.

Introduction: Monitoring of renal function in acute kidney injury in the pediatric population is complicated by the lack of age-related reference values of new biomarkers. Urinary netrin-1 is a new marker to demonstrate early kidney damage. Netrin-1 has a molecular mass of 72 kDa. It is therefore unlikely that it is filtered by the glomerulus under normal conditions. However, netrin-1 is highly induced after acute and chronic kidney injury and excreted in urine in humans. The aim of the study was to determine the normal concentrations of urinary netrin-1 in healthy full-term newborns.Material and methods: The study included 88 healthy full-term neonates (51 boys and 37 girls) born from normal, uncomplicated pregnancies. The concentration of netrin-1 was determined in urine obtained on the first or second day of life with a commercially available ELISA kit. Results: The urinary concentration of netrin-1 in newborns was independent of gender and time of urine collection. We found a negative correlation between both the urinary netrin-1 concentration and urinary netrin-1 concentration after normalization for urinary creatinine and the birth weight. Conclusions: This is the first study showing the urinary netrin-1 concentration in healthy full-term newborns. Future investigation is needed to confirm its potential role as a marker of kidney function in this age group.

IntroductionMonitoring of renal function in acute kidney injury in the pediatric population is complicated by the lack of age-related reference values of new biomarkers. Urinary netrin-1 is a new marker to demonstrate early kidney damage. Netrin-1 has a molecular mass of 72 kDa. It is therefore unlikely that it is filtered by the glomerulus under normal conditions. However, netrin-1 is highly induced after acute and chronic kidney injury and excreted in urine in humans. The aim of the study was to determine the normal concentrations of urinary netrin-1 in healthy full-term newborns.Material and methodsThe study included 88 healthy full-term neonates (51 boys and 37 girls) born from normal, uncomplicated pregnancies. The concentration of netrin-1 was determined in urine obtained on the first or second day of life with a commercially available ELISA kit.ResultsThe urinary concentration of netrin-1 in newborns was independent of gender and time of urine collection. We found a negative correlation between both the urinary netrin-1 concentration and urinary netrin-1 concentration after normalization for urinary creatinine and the birth weight.ConclusionsThis is the first study showing the urinary netrin-1 concentration in healthy full-term newborns. Future investigation is needed to confirm its potential role as a marker of kidney function in this age group.