Correlation of whole kidney hypertrophy with glomerular over-filtration in live, gender-mismatched renal transplant allografts.

AIM

Optimizing nephron supply to recipient demand is a non-immunologic determinant of renal allograft outcome. Nephron reduction is usually caused by physical donor-recipient mismatch, but its pathologic relevance remains to be determined.

METHODS

Thirty-one recipients of living donor renal transplants were divided into three subgroups: those who received transplants from the same gender (n = 6, Group 1) and those who underwent male-to-female (n = 8, Group 2) and female-to-male (n = 17, Group 3) transplants. Renal mass was evaluated by three-dimensional computed tomography (3D-CT) volumetry before and one year after transplantation. Glomerular volume was determined from protocol biopsies obtained one hour and one year after transplantation.

RESULTS

Histologically determined glomerular volume in biopsied tissues showed a significant linear correlation with allograft size on 3D-CT volumetry (P < 0.001, r = 0.625). Mismatches in body weight, glomerular volume and kidney volume ratios were significantly greater in female-to-male (Group 3) than in male-to-female (Group 2) transplants (P < 0.001 each). Despite the two groups having nearly equal graft filtration rates one year after transplantation, proteinuria rate was three-fold higher in Group 3 than in Group 2 (P < 0.001).

CONCLUSION

These findings suggest that too small graft size, frequent in female-to-male transplants, could cause hypertrophy in both kidneys and glomeruli, thereby affecting allograft function and survival.