Living Kidney Transplantation: Evaluation of Renal Function and Morphology of Potential Donors

The evaluation of potential living kidney donors requires an accurate study of renal function and morphology. The gold standard to assess renal function is the measurement of glomerular filtration rate (GFR). However, GFR is often estimated from serum creatinine (SCr), cystatin C (SCys), or creatinine clearance (CCr). Otherwise, GFR is predicted using formulas based on SCr or SCys. Ultrasound scanning evaluates morphology and dimensions, while scintigraphy provides information on morphofunctional symmetry of kidneys. The aim of this study in 79 potential donors was to assess the accuracy of the tests employed to estimate GFR and the utility of renal ultrasound and scintigraphy for morphofunctional evaluation of potential donors. GFR (clearance of 99mTc-DTPA) was compared with estimates obtained with Cockcroft and Gault (CG-CCr) and Modification of Diet in Renal Disease (MDRD-GFR) formulas, and from SCys (Cys-GFR). The correlation with GFR was statistically significant for SCys and for all estimates, but not for SCr. CCr showed a poor agreement with GFR, with a large range of agreement and a marked and significant overestimation of GFR (33.8 mL/min). The accuracy of CG-CCr and MDRD-GFR as indicators of a GFR < 80 mL/min was better than that of Cys-GFR and CCr. However, their mean prediction errors versus GFR were relevant. Renal dimensions, particularly renal volume, showed a good correlation with GFR. The correlation was higher than that of all prediction equations. The direct measurement of GFR remains the reference method to assess renal function in potential kidney donors. The measurement of renal dimensions can provide useful information also on renal function.