Longitudinal patterns of urine biomarkers in infants across gestational ages

Background

Urinary biomarkers may be indicators of acute kidney injury (AKI), although little is known of their developmental characteristics in healthy neonates across a full range of gestational age (GA). The purpose of this study was to examine patterns of urinary biomarkers across GA groups from birth to 3 months of age.

Methods

Fifty-two infants ranging from 24 to 41 weeks’ GA had urine assayed from birth through 3 months of age for 7 biomarkers including albumin (ALB), beta-2-microglobulin (B2M), cystatin-C (CysC), epidermal growth factor (EGF), neutrophil-gelatinase-associated lipocalin (NGAL), osteopontin (OPN), and uromodulin (UMOD).

Results

Of the seven urinary biomarkers, EGF and UMOD increased while others decreased with advancing GA. By 3 months of age, EGF and UMOD had increased in preterm infants to levels similar to those of term infants. UMOD/ml and EGF/ml appeared to be predominantly developmental biomarkers distinguishing estimated glomerular filtration rate (GFR) <30 ml/min/1.73 m² with receiver operator characteristic area under the curve (ROC-AUC) of 0.82; p?=?0.002. When factored by urine creatinine CysC/cr?+?ALB/cr were the most significant functional markers with AUC?=?0.79; p?=?0.004; sensitivity 96 %; specificity 58 %.

Conclusions

Among healthy neonates, urinary biomarkers vary with GA. These data support the use of urinary biomarkers in the assessment of normal kidney development in the absence of injury.