Creatinine and 51Cr-EDTA clearance after liver transplantation

We have compared glomerular filtration rate measured by creatinine clearance with that measured by 51Cr-EDTA clearance after liver transplantation. Fourteen pairs of values were obtained from seven patients on the first and second days after operation. There were wide discrepancies between the values for glomerular filtration rate measured by the two methods, with a regression co-efficient of 0.43 (p = 0.12). Both methods assume a steady state, with no change of extracellular fluid volume or in the rates of exchange between physiological compartments, that does not apply in the immediate period after operation. The results show the difficulties of using clearance techniques to assess renal function after major surgery. Since drug therapy may be based on these measurements, we suggest that in this group of patients isolated clearance values should not be used.