Résumé
As preventive and renoprotective interventions are available, early identification of nephropathy is crucial, and there is a growing demand for a clinically convenient and reliable marker of renal function. Diagnosis of impaired renal function is of particular importance in patients with cirrhosis of the liver. Moderately reduced renal function may be missed by the conventional parameters. Cystatin C is an endogenous marker of glomerular filtration rate independent of muscle mass. Therefore, the aim of this study was to investigate the value of serum cystatin C concentration for the detection of moderately impaired renal function in patients with different stages of cirrhosis in comparison with the conventional methods. Eighty seven patients with cirrhosis were included in this study; All cases in this work had been examined clinically and they are scored according to Child-Pugh score. Calculation of creatinine clearance [CrCl] by determining its concentration in timed urine collections and simultaneously in blood were done for all the patients. All blood samples were obtained on the day of urine collection for CBC, LFTs, pro-thrombin time, serum electrolyte, creatinine, urea, creatinine clearance and Cystatin C concentrations. The patients then divided into two groups depending upon the results creatinine clearance: [groupl] normal creatinine clearance group [creatinine clearance >/= 70 ml/min; n=50] and [group2] reduced creatinine clearance group [creatinine clearance 40n69 ml/min; n=37]. There was no significant difference in urea concentration between the two groups [30.7] group 2 versus [28.3] mg/100 ml, group 1. While serum Cystatin C concentrations [mean [SD]: 1.32 [0.51] v 1.03 [0.34] mg/1 [p=0.008] and creatinine concentrations 1.03 [0.52] v 0.86 [0.22] mg/100 ml [p=0.03] were higher in group 2 than in group 1. To confirm the diagnostic advantage of Cystatin C over creatinine and urea. Receiver-operator characteristics [ROC] shows at equal specificity, the sensitivity of cystatin C was increased almost throughout the ROC plot. At cut off concentrations of 1.0 mg [Cystatin C], 0.8 mg/100 ml [creatinine] and 27 mg/100 ml [urea],cystatin C exhibited significantly higher sensitivity than creatinine and urea [70%, 45.2%, and 43.9%; respectively p<0.05], Specificity and efficiency were not significantly different between parameters. The sensitivity of Cystatin C [88.5%] tended to be higher than that of creatinine [62.0%] and urea [55.3%] at equal specificity of [60%] in Child-Pugh class C patients. The results demonstrated that the diagnostic accuracy of plasma Cystatin C was better than plasma creatinine in identifying liver cirrhotic patients with reduced glomerular filtration rate. particularly with Child-Pugh class C patients, for early diagnosis of renal dysfunction