Cystatin C as a Renal Biomarker in Infants with Congenital Anomalies of the Kidney and Urinary Tract (CAKUT): A Systematic Review.

Background

The evaluation of renal function in neonates is challenging due to maternal creatinine transfer, reduced muscle mass, and non-steady-state physiology. Cystatin C emerged as a promising biomarker for assessing neonatal glomerular filtration rate. This review summarizes evidence from studies evaluating serum and urine cystatin C in healthy neonates and high-risk groups, including preterm newborns, neonates with acute kidney injury, and those with congenital kidney and urinary tract defects.

Methods

Twenty studies were included and qualitatively synthesized following PRISMA guidelines.

Results

In the included studies, serum cystatin C exhibited consistent postnatal patterns independent of maternal influence and showed a strong correlation with gestational age and renal development. Cystatin C enabled earlier detection of renal dysfunction compared to serum creatinine, especially in preterm infants and critically ill neonates. In babies with congenital renal abnormalities, cystatin C levels were associated with disease severity and clinical outcomes, while the cystatin C-based estimated glomerular filtration rate surpassed creatinine-based estimations. Urinary cystatin C correlated with tubular damage and increased risk of chronic kidney disease during follow-up.

Conclusions

Cystatin C is a reliable biomarker for evaluating neonatal renal function, although further standardization and validation are required for clinical implementation.