Correlation between serum cystatin C level and renal microvascular perfusion assessed by contrast-enhanced ultrasound in patients with diabetic kidney disease

Abstract

Objectives To investigate the relationship between serum cystatin C (CysC) levels and renal microvascular perfusion in patients with diabetic kidney disease (DKD). Methods A total of 57 patients with high CysC levels and 45 patients with normal CysC levels were enrolled. Data on clinical characteristics and laboratory examination results were also collected. Contrast-enhanced ultrasound (CEUS) of the kidneys was successively performed. The time-intensity curve (TIC) and related quantitative parameters of the kidneys were obtained by CEUS and the correlations between CysC and CEUS parameters were analyzed. Results Compared to the normal CysC group, the high CysC group had significantly lower wash-in area under the curve (WiAUC), wash-out area under the curve (WoAUC), and wash-in and wash-out area under the curve (WiWoAUC). In the normal CysC group, patients with Stage III chronic kidney disease (CKD) had higher AUCs than those with Stage I–II CKD (p < 0.05). In the high CysC group, patients with Stage IV–V CKD had lower wash-in AUC compared to patients with Stage I–II CKD (p = 0.023). The renal cortex microvascular perfusion parameters AUCs were positively correlated with the estimated glomerular filtration rate (GFR) (r = 0.280, 0.222, and 0.243), and CysC was inversely correlated with AUCs (r= −0.299, −0.251, and −0.273). Conclusions CEUS parameters reflected changes in renal microvascular perfusion in patients with DKD, while AUCs might be useful indicators of declining GFR in DKD patients with increased CysC.