Baseline glomerular size as a predictor of function in human renal transplantation

Background. Nonimmune mechanisms have been implicated in chronic renal allograft injury. In experimental studies, a strong correlation exists between glomerular size and the degree of glomerular sclerosis that develops after subtotal nephrectomy. Therefore, we assessed the impact of glomerular maximal planar area (MPA) in baseline biopsy specimens of human renal allografts on later graft function. Methods. The MPA was measured, by point counting and by computer planimetry, in postperfusion biopsy specimens from 96 allograft kidneys from nonhypertensive donors that had functioned for at least 2 years. Clinical data were analyzed throughout a follow-up period averaging 7.46±2.46 years. Results. Both methods produced equivalent estimates of MPA. MPA proved to be a strong predictor of late renal allograft function, with a significant correlation (P=0.02 to P<0.01) between MPA at baseline and later serum creatinine level and creatinine clearance, beginning at 6 months after transplantation and persisting through follow-up. Creatinine level at discharge and occurrence of rejection were also independent predictors, whereas donor age, gender and race, cold ischemia time, cadaveric versus living donor, delay in initial function, and HLA mismatch did not predict clinical outcome. Conclusion. Larger glomeruli at baseline, measured by a simple point-counting technique, provide an early predictor of risk for late allograft dysfunction and may identify a subpopulation of patients in whom treatment to prevent/ameliorate glomerular enlargement and/or hypertension may be efficacious.