Reference intervals of serum cystatin C for determining cystatin C-based glomerular filtration rates in preterm neonates.

Objective: The aim of this study is to determine the reference values of serum Cystatin C (CysC) and CysC-based estimated glomerular filtration rate (GFR) on the 3rd and 30th day of life in comparison with serum creatinine (Cr) and Cr-based estimated GFR.

Methods: This prospective study was performed on 52 preterm neonates whose gestational ages were between 28 and 34 weeks. Preterm neonates were divided into three groups according to the gestational age as follows: gestational week of 28-29 (group 1), gestational week of 30-32 (group 2) and gestational week of 33-34 (group 3). Blood samples were obtained on the 3rd and the 30th days of life. CysC was determined by particle-enhanced nephelometric immunoassay.

Results: The group 1 preterm neonates have higher CysC values (1.34 ± 0.1 mg/L) on the 3rd day of life than the group 2 (1.28 ± 0.2 mg/L) and the group 3 (1.24 ± 0.2 mg/L) but the differences were not significant (p > 0.05, for each). CysC values were independent of gestational age, birth weight and gender (p > 0.05, for each). No correlation was found between CysC and Cr on the 3rd day of life (p > 0.05).

Conclusions: CysC is regarded as an alternative for assessing the renal function in preterm neonates.