Histopathological evidence of poor prognosis in patients with vesicoureteral reflux

Patients with vesicoureteral reflux (VUR) often develop reflux nephropathy with focal segmental glomerular sclerosis (FSGS), although the exact mechan isms leading to the development of this complication are unknown. To determ ine the early changes in glomeruli of VUR patients that ultimately cause po or renal outcome, we examined morphometrically renal biopsies of 16 young p atients (age 10-20 years) with VUR at baseline pre-operatively, Patients we re divided into two groups, those who subsequently showed good prognosis an d those with poor renal prognosis at the end of a 10-year follow-up period. Patients with poor prognosis had worse proteinuria and lower creatinine at baseline than those with good prognosis. We also examined 40 age-matched c ontrol cases with previous temporal microhematuria and/or proteinuria but n ormal renal function and histology. Although the mean diameter of glomerula r capillary did not change in VUR cases irrespective of prognosis, glomerul ar capillary length increased by 125% in cases with good prognosis, and 335 % in cases with poor prognosis (P <0.01). Cystically expanded capillaries, with diameter > 95% of that in age-matched control. were detected in five o f eight patients with poor prognosis, but only in one of eight patients wit h good prognosis. In VUR, the number of podocytes/capillary diminished with increased length of the capillaries. Tuft adhesion to Bowman's capsule and podocyte detachment were primarily found in patients with poor prognosis. Our results suggest that lengthening of glomerular capillaries in young pat ients with VUR is a compensatory reaction to hyperfiltration. The appearanc e of cystic capillary expansion, podocyte detachment and/or tuft adhesion t o Bowman's capsule in such glomeruli may be important indicators of renal p rognosis in patients with VUR. These changes may lead to FSGS due to podocy te injury in patients with VUR, with subsequent deterioration of renal func tion.