Background: The criterion for performing a renal biopsy in children with idiopathic nephrotic syndrome (NS) showing microscopic hematuria at onset remains controversial.
Methods: To determine an adequate renal biopsy criterion in children with NS showing hematuria, the optimal cutoff for the maximum red blood cell (RBC) range in urine sediment to separate minimal change disease (MCD) from other glomerular changes was obtained by receiver operating characteristic analysis. We studied 29 children with NS showing hematuria who were screened from 1,320 patients who underwent renal biopsies between January 2001 and September 2011. Patients were divided into two groups according to the cutoff value to verify its validity.
Results: The optimal maximum RBC range was 30-49/high-power field (HPF). In group 1 (RBC ≤29/HPF, n = 14), 3 patients showed nephritis and the other 11 patients showed MCD. In group 2 (RBC ≥30/HPF, n = 15), 1 patient showed focal segmental glomerulosclerosis, 12 showed nephritis, and the other 2 showed MCD. These findings indicated that the ratio of non-MCD/MCD was significantly higher in group 2 than in group 1 (P < 0.01).
Conclusions: The use of maximum RBC range (30-49/HPF) for a criterion of renal biopsy in patients with NS showing hematuria may be reasonable for clinical practice.