The serum YKL-40 level is associated with vascular injury and predicts proteinuria in nephrotic syndrome patients.

Aim: Nephrotic syndrome (NS) is associated with an increased rate of cardiovascular events. The YKL-40 level is associated with atherosclerosis, endothelial dysfunction and proteinuria in renal and non-renal populations. The aim of this study was to investigate the relationships between the YKL-40 level and both vascular injury and proteinuria in NS patients. Methods: Sixty-nine NS patients and 20 healthy subjects were enrolled in the present study. The endothelial function was assessed according to the flow mediated dilatation (FMD) and the degree of arterial stiffness was determined based on the pulse wave velocity (PWV). The serum YKL-40 levels were measured using ELISA. Results: The YKL-40 levels and PWV values were higher and the FMD values were lower in the NS patients than in the healthy controls. However, the CA-IMT and LVEF levels were not statistically different between the two groups. The patients were divided into three groups with respect to the extent of proteinuria: the normoproteinuria group (n:18), non-nephrotic proteinuria group (n:33) and nephrotic proteinuria group (n:18). Consequently, the YKL-40 levels and PWV values were significantly increased and the FMD values were decreased in the nephrotic proteinuria group compared to that observed in both the non-nephrotic proteinuria and normoproteinuria groups. Furthermore, the YKL-40 level correlated with the FMD and PWV values in the NS patients. In addition, proteinuria correlated with the YKL-40, FMD, PWV, eGFR and fasting LDL cholesterol values in this patient group. Multivariate linear regression analyses showed that the YKL-40 and eGFR values were effective in predicting proteinuria in the NS patients. Conclusions: The serum YKL-40 level is associated with endothelial dysfunction and increased arterial stiffness in NS patients and may be an indicator of the level of proteinuria in this patient population.