Nephrogenesis, Renal Function, and Biomarkers in Preterm Newborns

Background: The survival of premature newborns increased in the last decades due to advances in neonatal care. The physiology of this group is still under investigation, once the incomplete organogenesis entails functional particularities that are not yet clarified by current clinical knowledge. The immature kidneys are especially susceptible to acute injury with potential long-term impacts. Current diagnostic parameters of acute kidney injury are limited among the preterm population. The commonly used serum creatinine protein constitutes a poor biomarker to predict early lesions as it is susceptible to several factors, including muscle mass and gestational age. Objective: The present review explores the evidence on nephrogenesis, renal function, and acute kidney injury in neonatology, as well as studies on renal function biomarkers and their potential application for diagnosis, follow-up, and prognosis in preterm newborns. Results: Premature newborns reach full-term gestational age with reduced number and quality of nephrons. Consequently, the glomerular filtration rate and tubular function become impaired and are proportional to the gestational age. Despite having a high incidence among the pediatric population, acute kidney injury is still underdiagnosed and poorly managed due to the absence of proper, sensible, and non-invasive biomarkers. Although cystatin C, NGAL, and KIM-1, are promising urinary markers, current literature remains inconsistent. Conclusion: Further research is needed to properly identify and standardize sensible and specific urinary biomarkers to better assess kidney function in preterm newborns.