Cystatin C as a marker of renal function immediately after liver transplantation

To verify whether cystatin C may be of some use as a renal function marker immediately after orthotopic liver C transplantation (OLT), we compared serum cystatin C (S-cyst), serum creatinine (S-cr), and creatinine clearance (C-cr), and Scr levels with the glomerular filtration rate (GFR). On postoperative days 1, 3, 5, and 7, S-cyst was measured in simultaneously drawn blood samples, whereas Ccr was calculated using a complete 24-hour urine collection. The GFR was determined on the same days by means of iohexol plasma clearance (I-GFR). The correlation between 1/S-cyst and I-GFR was stronger than that of 1/S-cr or C-cr (P < 0.01). In the case of moderate reductions in I-GFR (80-60 mUminute/1.73 m(2)), Scr remained within the normal range, whereas the increase in S-cyst was beyond its upper limit; was twice its for I-GFR reductions to lower levels (59-40 mUminute/1.73 m(2)), Scr increased slightly, whereas S-cyst upper normal limit. When we isolated all of the I-GFR values on days 3, 5, and 7 that were >= 30% lower than that recorded on the first postoperative day, S-cyst 0.01) levels were increased, whereas C-cr (P < 0.0001) and Scr (P < remained unchanged (P = 0.09). Receiver operating characteristic (ROC) area-under-the-curve analysis showed that the diagnostic accuracy of S-cyst was better than that of S-cr and C-cr, S-cyst levels of 1.4, 1.7, and 2.2 mg/L respectively predicted I-GFR levels of 80, 60, and 40 mUminute/1.73 m(2). In conclusion, cystatin C is a reliable marker of renal function during the immediate post-OLT period, especially when the goal is to identify moderate changes in GFR.