Lower donated kidney volume is associated with increased risk of lower graft function and acute rejection at 1 year after living donor kidney-a retrospective study.

Kidney volume has been proven to be a surrogate marker of nephron mass and renal function. We studied 190 donor and recipient pairs undergoing living donor kidney transplantation at our institution during 9 years. Different metrics of donor kidney volume (DKV) were explored: alone or indexed to recipient's anthropometry, as body surface area (BSA). DKV/BSA (min. 49.7; P33rd 77.7; P67th 95.3; max. 176 cm3 /m2 ) was chosen given its higher correlation with eGFR at 1 year, and recipients were divided according to its tertiles (T). The eGFR at 1 year was lower in T1, when compared with T2 (P = 0.015) and T3 (P < 0.001). In a multivariable model, a regression spline revealed that a DKV/BSA lower than 80 was significantly associated with an eGFR at 1 year <60. In the first 6 years, the overall annual eGFR slope was -0.90 ml/min/year. Acute rejection occurred in 19%, 11%, and 0% of patients in T1, T2, and T3, respectively (P < 0.001). DKV/BSA increased stepwise from cellular- (n = 12) to antibody-mediated (n = 7) AR cases and to those without AR (n = 171; P = 0.002; no AR versus cellular AR). Lower DKV/BSA ratio was associated with significantly worse graft function and higher incidence of AR. Hence, it can be a tool for better selection of donors in order to improve graft outcomes, particularly in the setting of multiple potential living donors or kidney paired exchange programs.