Quantitative morphometry of renal biopsies prior to cyclosporine in nephrotic syndrome

Use of cyclosporine (CsA) in the management of children with steroid-resistant (SRNS) and steroid-dependent (SDNS) nephrotic syndrome has become increasingly popular in recent years. Although most children receive a renal biopsy prior to initiation of CsA, the relationship between initial renal histology and the subsequent clinical response to CsA is not known. We analyzed the correlation between pre-CsA segmental and global glomerular scarring and interstitial fibrosis and the subsequent response to CsA in 23 children (5.6±1.0 years, Mean±SEM) with SDNS (n=8) and SRNS (n=15) treated with CsA for 24.2±3.8 months and followed for 28.0±4.1 months. Complete remission was obtained in 78% of patients within 67.6±16 days, while 18% had a partial response and 4% no response. Quantitative histological analysis revealed a trend toward partial rather than complete response with increasing segmental glomerular (P=0.13), global glomerular (P=0.05), and interstitial (P=0.08) scarring, and among patients with minimal change nephrotic syndrome versus IgM nephropathy versus focal segmental glomerulosclerosis. Among complete responders, linear regression analyses revealed no correlation between time to response and pre-CsA glomerular or interstitial scarring. We conclude that increased glomerular or interstitial scarring on a pre-CsA renal biopsy tends to correlate with a partial, rather than complete, response to CsA in childhood nephrotic syndrome.