Reference intervals for serum cystatin C in neonates and children 30 days to 18 years old

Background: Serum cystatin C (CysC) is a promising biomarker of renal function, which has higher accuracy and sensitivity when compared with creatinine. To better utilise serum CysC in clinical practice, this study aimed to establish continuous paediatric reference intervals (RIs) for serum CysC.
Methods: The study subjects consist of healthy term neonates, and children aged 30 days to 18 years. Venous blood samples were collected and serum CysC levels were measured using the immunotubidimetric measurement principle. Fractional polynomial regression model and quantile regression was applied in the statistical analysis to generate continuous RIs.
Results: A total of 378 samples with equal numbers of males and females were analysed for serum CysC and no outliers were found in this analysis. The continuous RIs are presented as equations and graphical scatterplots.
Conclusions: This study established continuous paediatric reference intervals (RIs) for serum CysC in a healthy term neonates and children. The continuous RIs generated from this study showed the age-based dynamic changes as well as blood group and gender-specific differences for serum CysC.