Living kidney donors incur a small increased risk of end-stage kidney disease (ESKD), of which pre-donation glomerular filtration rate (GFR) is an important determinant. As a result, kidney function assessment is central to the donor candidate evaluation and selection process. This article reviews the different methods of GFR assessment including estimated GFR, creatinine clearance and measured GFR, and the current guidelines on GFR thresholds for donor acceptance. Estimated GFR obtained using the 2009 Chronic Kidney Disease Epidemiology Collaboration equation, while the best of estimating estimations, tends to underestimate and has limited accuracy, especially near normal GFR values. In the United States, the Organ Procurement and Transplantation Network policy on living donation mandates either measured GFR or creatinine clearance as part of evaluation. Measured GFR is considered the gold standard, although there is some variation in performance characteristics depending on the marker and technique used. Major limitations of creatinine clearance are dependency on accuracy of timed collection, and overestimation as a result of distal tubular creatinine secretion. GFR declines with healthy aging, and most international guidelines recommend use of age-adapted selection criteria. The 2017 Kidney Disease: Improving Global Outcomes Guideline for the Evaluation and Care of Living Kidney Donors diverges from other guidelines and recommends using absolute cut-off of <60 ml/min/1.73m2 for exclusion and of ≥90 ml/min/1.73m2 for acceptance, and determination of candidacy with intermediate GFR based on long-term ESKD risk. However, several concerns for this strategy exist, including inappropriate acceptance of younger candidates due to underestimation of risk, and exclusion of older candidates whose kidney function is in fact appropriate for age. Role of cystatin C and other newer biomarkers, as well as data on impact of pre-donation GFR on not just ESKD risk but also advanced chronic kidney disease risk and cardiovascular outcomes are needed.
Estimated or Measured GFR in Living Kidney Donors Work-up?
