Background and purpose: Serum creatinine and its derived formulae in estimating glomerular filtration rate is not accurate in cirrhotic patients because of decreased muscle mass and secretion and excretion functional impairment of liver. This study aimed at investigating the accuracy of serum cystatin C in determining GFR and examining the relationship between synthetic and excretory liver function with glomerular filtration rate in cirrhotic patients.
Materials and methods: In this cross-sectional study, 35 patients with cirrhosis and 35 age and sex matched healthy controls enrolled. Serum creatinine, LFT, FBS, LDL, HDL, cholesterol, triglycerides, albumin, globulin, and cystatin C and also 24-hour urinary urea and creatinine were measured. GFR was estimated by three measurement methods and the relationship between GFR and Child score was evaluated.
Results: The mean age of participants was 39.15±13.93 years and male patients included 48.57%. The most common cause of cirrhosis was autoimmune cirrhosis. GFR based on creatinine in two different formulas was higher than that in control group but the GFR based on cystatin C was significantly lower in cirrhotic group (p<0.001). The secretory and excretory functions of liver were not significantly correlated with GFR in cirrhotic patients (p>0.05). Correlation coefficient between GFR (based on cystatin C) and Child-square was 0.199 (p= 0.251).
Conclusion: GFR based on cystatin C is more accurate in cirrhotic patients.  On the other hand, there was a moderate negative correlation between GFR (based on cystatin C) and Child-square that can be helpful in prediction and early detection of renal dysfunction in cirrhotic patients.