Glomerular filtration rate assessment in individuals after orthotopic liver transplantation based on serum cystatin C levels

Individuals after orthotopic liver transplantation (OLT) often show renal dysfunction, which may substantially affect the post-OLT course. Renal function after OLT is commonly assessed by means of serum creatinine (S-cr) concentration or renal creatinine clearance (C-cr). A glomerular filtration rate (GFR) estimate based on Sa level is not accurate enough because even a more marked decrease in GFR need not be associated with an increase in S-cr level, especially in jaundiced patients. The study intends to try to estimate GFR in individuals after OLT by means of determining serum cystatin C (S-cyst) concentrations. In 58 individuals (mean age, 49 +/- 7 years; 31 men, 27 women) at various intervals from OLT (mean, 14 +/- 10 months), GFR was estimated by using simultaneous determinations of S-cyst, S-cr, C-cr, and renal inulin clearance (C-in). In most subjects (91.3%), C-in was decreased to less than the lower limit of normal (80 mL/min/1.73 m(2)). A significant correlation (r = 0.70; P < .001) was found between 1/S-cyst and C-in. Receiver operating characteristic analysis was performed on S-cyst and S-cr using a C-in cutoff value of 80 mL/min/1.73 m. The area under the curve for S-cyst was 0.912 +/- 0.044, and that for S-cr, 0.899 +/- 0.049. There was no statistically significant difference between these values. The sensitivity for a S-cyst level of 1.20 mg/L (upper limit of normal value) to detect a decrease in GFR (measured as C-in) below the lower limit of normal (80 mL/min/1.73 m(2)) was 96.1%. The sensitivity of S-cyst level was significantly greater (P < .0l) than the sensitivity of S-cr level for men and at borderline significance for women (P = .05). Findings support the assumption that a S-cyst level less than 1.2 mg/L indicates with a high degree of probability (P < .001) that GFR is not decreased to less than the normal limit. S-cyst assessment in individuals after OLT could be proposed as a confirmatory test of a decrease in GFR in individuals with normal S-cr levels.