Evaluation and predictive factors of renal function progression using cystatin C and creatinine in neonates born with CAKUT.

Background: Congenital anomalies of the kidney and urinary tract (CAKUT) is a main cause leading to endstage renal disease (ESRD) during childhood occurring at a frequency of 1 in every 500 pregnancies. No early predictive markers of long-term renal function (RF) are validated in these neonates. The aim of this study was to compare CysC and creatinine (creat) as markers of RF from birth to 2 years and to identify factors of RF progression.
Methods: The 56 patients included in this study were followed for a median of 235 days (137 - 739). Repeated measures of CysC and creat during 2 years of RF evaluation were taken in 28 patients. Changes in RF with age were analyzed. Potential risk factors for RF progression were analyzed for: type of kidney disease (KD), bilateralism of KD, prenatal pelvic dilatation, reflux and initial relative RF (RRF) asymmetry obtained by scan.
Results: With age, a rapid decrease of CysC (16.3%, p < 0.001), and creat (68.6%, p < 0.001) was observed at 1 month. Between 1 month and 1 year, CysC decreased 4% per month (p < 0.001) and creatinine stabilized (+ 1.9%/m, p = 0.11). After 1 year, both CysC and creat stabilized. In the multivariate model, CysC significantly increased in patients with bilateralism (p = 0.004) or asymmetric RRF (p = 0.03). Creat was not significant.
Conclusion: CysC was a better marker than creat to follow RF in neonates with CAKUT. Using CysC, bilateralism, and RRF asymmetry were significantly associated with RF progression.