Post-kidney donation glomerular filtration rate measurement and estimation

Abstract

BackgroundLong-term consequences associated with kidney donation are controversial. Pre- and post-donation glomerular filtration rates (GFRs) are determinants of renal and cardiovascular risk weighting. In Latin America, there is limited experience in evaluating kidney function using GFR measurement techniques in kidney donors. The MDRD 4-variable and CKD-EPI equations are considered reasonable options. The objective of this study was to evaluate the performance of the MDRD and CKD-EPI equations in post-nephrectomy GFR dynamics in kidney donors. Materials and methodsA prospective cohort study with GFR measurement and estimation in 189 kidney donors who underwent nephrectomy between 2007 and 2016 at the Hospital Privado Universitario de Córdoba [Private University Hospital of Córdoba] in Córdoba, Argentina. GFRs were evaluated before and after nephrectomy by iothalamate clearance determined by HPLC and by the MDRD and CKD-EPI equations for estimating GFR. Two groups were formed for this study: Group 1 (n=107), with an evaluation time subsequent to GFR stabilization (3 months) of up to 5 years, and Group 2 (n=82), with an evaluation time of 5–10 years following donation. Measured GFR (mGFR) was assessed by iothalamate clearance determined by HPLC. ResultsRenal compensation values were 61.9% (52.0%–71.1%) and 75.6% (64.9%–84.4%) for Group 1 (n=107) and Group 2 (n=82), respectively. MDRD underestimated the GFR in 3.2% (90ml/min/1.73m2) and 38.6% (60ml/min/1.73m2) compared to the mGFR, and CKD-EPI underestimated the GFR in 2.6% (90ml/min/1.73m2) and 13.8% (60ml/min/1.73m2). Diagnostic performance was evaluated with a ROC curve (mGFR<60ml/min/1.73m2) for MDRD (ABC=0.66; CI: 0.59–0.73; sensitivity: 98.7%; specificity: 63.3%) and for CKD-EPI (ABC=0.79 CI: 0.73–0.85; sensitivity: 96.9%; specificity: 76.4%. Estimated GFR (eGFR) showed poor performance for estimating the glomerular filtration rate in the post-nephrectomy follow-up of donors over 50 years of age. ConclusionsEquations for estimating GFRs showed poor performance for long-term follow-up of post-nephrectomy GFRs. Measuring GFRs to determine kidney function is recommended in the screening and follow-up of some donors under the current selection criteria.