Serum cystatin C can be used as a marker of renal function even in patients with intestinal urinary diversion

Recently, serum cystatin C (CysC) has been used as a novel marker of renal function. However, there is a lack of data on CysC levels in patients with intestinal urinary diversion (UD). Here we report CysC levels in such patients. We prospectively observed 38 patients who were diagnosed with bladder cancer and subsequently treated with radical cystectomy and UD at our institution in 2012 and 2013. Serum creatinine (sCr) and CysC were obtained optionally at the same time at least 1 month after radical cystectomy and UD. The median CysC and sCr concentrations were 1.12 mg/L (range 0.75–2.47 mg/L) and 0.99 mg/dL (range 0.61–2.22 mg/dL), respectively. The median estimated concentrations of glomerular filtration rate (GFR) based on CysC (eGFRcys) and GFR based on creatinine (eGFRcreat) were 61.08 mL/min/1.73 m2 (range 22.64–99.89 mL/min/1.73 m2) and 58.01 mL/min/1.73 m2 (range 23.48–91.82 mL/min/1.73 m2), respectively. CysC had a significant correlation with sCr (r = 0.8607, p < 0.0001) and eGFRcreat (r = −0.8993, p < 0.0001). eGFRcys also had a significant correlation with eGFRcreat (r = 0.8104, p < 0.0001). The correlation between CysC and sCr was strong and the correlation coefficient was equivalent to that in patients without UD. The results suggest that CysC is not affected by UD and can be used as a marker of renal function similarly to sCr in patients with UD.