Donor kidney volume relative to recipient body size and longitudinal graft function in living donor kidney...

Donor nephron mass and recipient metabolic demand may influence graft outcomes after kidney transplantation. However, the clinical significance of kidney volume-based size mismatch remains unclear. We evaluated the association between donor kidney volume relative to recipient body size and short- and long-term graft function after living donor kidney transplantation (LDKT).

We retrospectively analyzed 170 LDKT recipients. Donor kidney volume (DKV) was quantified using preoperative computed tomography and indexed to recipient body surface area (DKV/RBSA). The primary outcome was 12-month eGFR < 30 mL/min/1.73 m². Multivariable regression assessed 12-month graft function, and the incremental value of DKV/RBSA was compared with conventional mismatch indices. Longitudinal eGFR was analyzed using a linear mixed-effects model.

Impaired graft function occurred in 27 recipients (15.9%). DKV/RBSA was not associated with the primary binary outcome (OR 0.85 per 10 mL/m²; P = 0.208) but was independently associated with continuous 12-month eGFR (β = 1.94 per 10 mL/m²; P < 0.001). Adding DKV/RBSA increased the adjusted R² from 0.123 to 0.190, representing the largest increase among the mismatch indices examined. Higher DKV/RBSA remained associated with eGFR through 10 years (β = 1.37 per 10 mL/m²; P = 0.004), with no significant time interaction (P = 0.194).

Higher DKV/RBSA was associated with better continuous and longitudinal graft function but not with the prespecified binary outcome. CT-derived DKV/RBSA may provide complementary information on donor-recipient size matching, although external validation is required before clinical application.