ACCURACY OF CIMETIDINE-CORRECTED SERUM CREATININE, CREATININE CLEARANCE AND CALCULATED CREATININE CLEARANCE TO ASSESS THE GLOMERULAR FILTRATION RATE IN LONG-TERM KIDNEY-PANCREAS AND LIVER TRANSPLANT PATIENTS

Abstract

P863 Serum creatinine (Scr) and the endogenous creatinine clearance (CrCl) overestimate the glomerular filtration rate (GFR). Cimetidine decreases the tubular secretion of creatinine and improves the accuracy of the CrCl and calculated (Calc) CrCl (based on the Cockroft-Gault formula), in pts with various renal diseases. Aim: To determine the effect of cimetidine on renal function markers (Scr, CrCl and the CalcCrCl) and to correlate these markers with the radionuclide GFR in long-term recipients of kidney/pancreas (KP) Tx and liver (L) Tx. Methods: We enrolled 18 pts (5 women, 13 men, 46±8 yrs), who were >1 yr (28±20 mo.) post-KPTx and 38 pts (14 women, 24 men, 61±11 yrs), who were >1-yr (57±34 mo.) post-LTx. All the pts were on a calcineurin inhibitor. All the pts received cimetidine 800 mg t.i.d for 1 day and collected urine (24-hr) during the same day, the day before the annual radionuclide GFR. Scr, CrCl and the CalcCrCl (cimetidine-corrected) were measured on the day of the annual GFR. Results: LTx pts were older (P<0.0001). Cimetidine was well tolerated and no side-effects were observed. The cost of 2,400 mg of cimetidine was lower than the cost of the radionuclide GFR (CDN $0.48 vs. $66.00). Table 1. Effect of Cimetidine on renal function markersFigureTable 2. Correlation (r2) between the GFR and cimetidine-corrected markers of renal functionFigureaP = 0.006, bP = 0.0003, cP < 0.0001, dP = 0.0007, cP = 0.034 Conclusion: Renal function markers are overestimated in long-term recipients of KPTx and LTx. Our results suggest that cimetidine improves the accuracy of CrCl and CalcCrCl to assess the GFR in KPTx pts. The cimetidine-corrected CalcCrCl, may become a cost-effective alternative to assess the GFR in these pts. In LTx pts, cimetidine-corrected Scr appears to correlate better with the GFR compared to the cimetidine-corrected CrCl and CalcCrCl. A modified CalcCrCl formula needs to be developed to assess the GFR in LTx pts.