Analysis of glomerular filtration rate, serum cystatin C levels, and renal resistive index values in cirrhosis patients

Background: The aim of this study was to evaluate the relation of glomerular filtration rate (GFR) to serum cystatin C levels, renal resistive index (RRI), serum creatinine and creatinine clearance in patients with different stages of cirrhosis. Methods: The study sample was 25 cirrhotic patients (10 females and 15 males; mean age 57.3±2.04 years), 10 in the compensated stage without ascites and 15 in the decompensated stage with new-onset ascites. None had azotemia nor were on diuretic treatment. The control group comprised 25 healthy adults (11 female and 14 men; mean age 56.56±1.91 years). Serum cystatin C, RRI, serum creatinine and creatinine clearance were measured. GFR was determined by technetium 99m -diethylene triamine pentaacetic acid renal scintigraphy. Results: Cirrhosis cases had lower mean scintigraphic GFR than controls (64.5±4.03 vs. 87.96±4.16 mL/min, p<0.05). Serum cystatin C and RRI were significantly higher in the cirrhotic group compared to controls (1.16±0.09 mg/L and 0.68±0.01 vs. 0.86±0.03 mg/L and 0.64±0.01, respectively; p<0.05). Subgroup comparative analysis showed that only two parameters, scintigraphic GFR and serum cystatin C, were significantly different between compensated and decompensated cirrhotics (75.62±4.9 mL/min and 0.89± 0.07 mg/L vs. 57.23±5.14 mL/min and 1.34±0.13 mg/L, respectively; p<0.05). Scintigraphic GFR showed significant correlation with cystatin C, but not with serum creatinine or creatinine clearance (r=-0.877, p<0.05) in decompensated patients. No correlation was observed between scintigraphic GFR and RRI or between serum cystatin C and RRI in all subjects. A receiver operator characteristics curve showed that cystatin C at a cutoff value of 1.01 mg/L can significantly differentiate patients with GFR <70 mL/min with 80% sensitivity and 80% specificity. Conclusions: Serum cystatin C, but not serum creatinine or RRI measurement, correlates with GFR in each stage of liver failure and has a significant diagnostic advantage in detecting lower GFR in such cases.