1. ¹Nephrology Department, Hospital Universitari de Bellvitge, c/Feixa Llarga s/n, L'Hospitalet, Barcelona, Spain
2. ²Pathology Department, Hospital Universitari de Bellvitge, c/Feixa Llarga s/n, L'Hospitalet, Barcelona, Spain

Correspondence: D Serón, Nephrology Department, Hospital Universitari Bellvitge, C/Feixa Llarga s/n, 08907 L'Hospitalet, Barcelona, Spain. E-mail: 17664dsm@comb.es

Received 9 February 2006; Revised 21 March 2006; Accepted 18 April 2006; Published online 21 June 2006.

Abstract

After transplantation, glomerular volumes increases and large glomerular volume at 4 months is associated with better renal function. The aim is to characterize glomerular adaptation after the fourth month in two serial protocol biopsies and its relationship with subclinical rejection and chronic allograft nephropathy (CAN). Mean glomerular volume (V_g) was estimated according to the Weibel and Gomez method in a 4-month and 1-year serial protocol biopsies in 61 stable grafts. Glomerular enlargement (V_g) was calculated as the V_g difference between both biopsies. Banff schema was used to evaluate renal biopsies. V_g increased from 4.42.4 to 5.72.6 10⁶ m³ (P<0.001). Mean V_g was 1.0 10⁶ m³. Patients with V_g<1 were considered as patients with impaired glomerular enlargement (n=29). Impaired glomerular enlargement was associated with increased acute index score in the 4-month (1.831.56 vs 1.061.48; P<0.05) and 1-year protocol biopsies (1.521.59 vs 0.621.07; P<0.05). Impaired glomerular enlargement was also associated with increased progression of chronic lesions between the 4-month and 1-year biopsy in the glomerular (0.170.38 vs 0.550.63; P<0.01), tubular (0.380.56 vs 0.830.85; P<0.01), and interstitial compartment (0.410.57 vs 0.900.86; P<0.01). The proportion of sclerotic glomeruli between both biopsies increased in patients with impaired glomerular enlargement (1.53.9 to 5.310.1, P<0.05) while it did not modify in patients with glomerular enlargement (2.17.3 vs 2.64.5; P=NS). During the first year, glomeruli enlarge but this adaptation mechanism is impaired in patients with subclinical rejection. Moreover, impaired glomerular enlargement is associated with progression of CAN.