Evaluation of renal function in potential living kidney donors

Background, Most transplant centers in the United States, including our own , use creatinine clearance (C-Cr) to estimate glomerular filtration rate (G FR) in potential living kidney donors. The purpose of this study was to eva luate our experience with estimation of donor GFR by C-Cr and to explore ot her potential strategies for evaluation of renal function in donors. Methods. Potential donors performed one to three outpatient urine collectio ns for C-Cr measurement. Those with low or inconsistent results underwent m easurement of GFR by a radionuclide method not dependent upon urine collect ion (rGFR). The ability to determine adequacy of urine volume by creatinine excretion rate (UVCr) was examined. GFR was also predicted from serum crea tinine (S-Cr) by using two prediction equations [Cockcroft-Gault and that f rom the Modification of Diet in Renal Disease Study (MDRD)]. The effect of indexing GFR by height as opposed to body surface area (BSA) was explored. Results. Over a 5-year period, 22 potential donors ( approximate to 10% of total evaluated) had inconsistent or low C-Cr. Most had normal rGFR and, pr esumably undercollected their urine. However, several female donors had tru ly low GFR by rGFR The accuracy of C-Cr (compared with rGFR) was not predic ted by UVCr in a clinically useful way. The prediction equations did not ha ve sufficient accuracy or precision to replace rGFR in this population. ind exing GFR estimates by BSA introduced a bias toward lower values in females ; this was largely overcome by indexing GFR by height Conclusions, Evaluation of GFR in potential living donors by C-Cr is not ve ry useful, A more promising strategy could be developed predicting GFR from S-Cr and indexing the results by height rather than BSA. The optimum metho d for evaluation of renal function in kidney donors deserves further study.