RENAL HISTOLOGY AND INTERSTITIAL MORPHOMETRY IN NEPHROTIC PATIENTS TREATED WITH CYCLOSPORINE

Renal biopsies were performed in six adult patient with steroid-resistant or steroid-dependent idiopathic nephrotic syndrome after low-dose CsA therapy. Their histologic diagnoses were MCD (3), Mesangial proliferative GN (1) and FSGS (2). CsA therapy was started at 3 mg/kg/day. Prednisone at 10 mg/kg/day was also given. Remission after therapy was noted in all but one (FSGS/steroid resistant) patient. Mean CsA dose ranged from 3 to 4 mg/kg/day and blood CsA levels from 56 to 110 ng/ml. Therapy was maintained for 12-15 months in CsA responders and for three months in the case of CsA resistance. GFR (Clearance of 51 Cr EDTA) remained within normal limits. Renal biopsies were performed prior to the start of CsA treatment and repeated in the days before the end of therapy. Using semiquantitative methods (Score 1+ to 4+), slight (1+) glomerular and tubulointerstitial sclerotic changes were disclosed only in the two cases with previous steroid-resistance. No vascular changes were observed. Morphometrical analysis of the interstitial surface (IS) was performed by point-counting methods. A decrease of IS during therapy was observed in two patients wich was associated with a good subsequent clinical course: Sustained remission of nephrotic syndrome after stopping CsA (Follow-up 34 months). On the contrary, increased IS during therapy was associated with early relapse after discontinuation of CsA (3 cases) or CsA resistance (1 case).