Remi George Thomas*, Balaraman V, Vasudevan C, Senthilkumar RP, Thirumalvalavan and Murugesan V
Department of Nephrology, Kilpauk Medical College, IndiaFulltext PDF
Aims: i) To measure Glomerular Filtration Rate (mGFR) using 99Tc DTPA in patients with Child Pugh C cirrhosis and normal serum creatinine levels. ii) To compare the performance of creatinine and cystatin C-based equations (eGFRs) to 99TcDTPA GFR in the same group.
Materials and Methods: We selected a group of 65 consecutive patients with advanced liver cirrhosis and apparently normal renal function by serum creatinine alone. Patients with confounding and reversible factors were excluded. Demographic data, blood, urine and imaging tests along with simultaneous measurement of serum creatinine and cystatin C were analyzed. The GFR was measured by 99Tc DTPA scintigraphy (mGFR) in 41 patients. We compared the performance of Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI-Creatinine, CKD-EPI-Cystatin C and CKD-EPI-Creatinine-Cystatin C) and MDRD equations for bias (mean difference), precision (root mean square error) and accuracy (P10 and P30). Bland-Altman plots were used to show the agreement of eGFR and mGFR.
Results: Sixty one percent of patients had significant renal dysfunction (GFR ≤ 60 ml/min/1.73 m2 ) by 99TcDTPA in our study. Three patients were already in stage 4 CKD despite normal serum creatinine values. Cystatin C-based equations estimated the mGFR better compared to creatinine based equations. CKD-EPI-Creatinine-Cystatin C combined equation had the least bias (-2.3), superior precision (7.1), highest P30 accuracy (78%), good sensitivity (87.5%) and best specificity (96%) in our study.
Discussion: Creatinine based GFR estimation is fallacious in cirrhosis. Cystatin C and equations based on it may be worthwhile in liver disease. Conclusions: i) Two-thirds of patients with cirrhosis had significant renal impairment despite normal serum creatinine. Isolated serum creatinine values are misleading in cirrhosis. ii) Cystatin C unmasks renal dysfunction in these patients. CKD-EPI-Creatinine-Cystatin C equation showed the best correlation and accuracy with 99TcDTPA GFR in our study.
Cystatin C; Cirrhosis; Glomerular filtration rate; 99TcDTPA
Thomas RG, Balaraman V, Vasudevan C, Senthilkumar RP, Thirumalvalavan, Murugesan V. Serum Cystatin C Unmasks Renal Dysfunction in Cirrhosis and Performs Better in GFR Estimation. Ann Clin Hepatol. 2019; 3(1): 1009.