Factors Associated With Residual Kidney Function and Proteinuria After Living Kidney Donation in the United States

INTRODUCTION Kidney transplantation from living donors remains the optimal treatment for patients with advanced chronic kidney disease (CKD) or end-stage renal disease (ESRD). In the past decade, efforts to increase the living donor pool have included acceptance of older donors, obese donors, and donors with hypertension or with metabolic syndrome. Such studies have shown acceptable function and allograft survival in the recipient, but safety and outcomes in higher risk living donors remain a priority for study. Kidney function typically rebounds quickly following unilateral nephrectomy in healthy donors, with a compensatory increase in functional capacity of the contralateral kidney by approximately 20%–40%. A relative lack of augmentation of kidney function after donation could relate to factors such as older age, where a greater degree of glomerulosclerosis and a reduction in functioning glomeruli may be seen relative to younger donors. Additionally, donor obesity, hypertension, and metabolic syndrome may impact renal compensation. Initial relative lack of recovery of function is predictive of a reduction in kidney function beyond 1 year after donation. Proteinuria, a well-characterized marker of kidney disease, is found in a significant subset of kidney donors as well, and increases in prevalence with time from donation. Proteinuria may be a consequence of single nephron hyperfiltration due to reduced renal mass. It is not clear whether a relative lack of renal recovery correlates with the development of proteinuria after donation. Reporting on donor follow-up has been incomplete in recent years, particularly in higher risk donor populations. Recent tracking of living donor variables has been mandated by the United Network for Organ Sharing Received 30 August 2019. Revision received 28 January 2020.