RENAL EFFECTS OF CYCLOSPORINE-A IN CHILDREN TREATED FOR IDIOPATHIC NEPHROTIC SYNDROME

Little data have been published on tubular renal function during cyclo sporin A treatment in children without transplants. We studied 12 youn g subjects (mean age 10 years) with steroid-responsive idiopathic neph rotic syndrome and with signs of steroid toxicity. After achieving rem ission with prednisone 60 mg/m2, 8 children started cyclosporin A ther apy (6 mg/kg/day) (group A) and 4 children were given cyclophosphamide 2.5 mg/kg/day (group B). The latter were considered as controls toget her with 10 other children with idiopathic nephrotic syndrome in compl ete remission and off therapy (group C). We monitored creatinine clear ance and tubular handling of beta2-microglobulin, sodium, phosphorus a nd uric acid for one year. Cyclosporin A induced a decrease in creatin ine clearance with a decrease in fractional excretion Of beta2-microgl obulin; sodium excretion was similar in the two treated groups and a t ransient decrease in fractional excretion of uric acid was seen only i n patients receiving cyclosporin A. Both groups showed an increased re nal threshold phosphate concentration. Our results suggest that in chi ldren, cyclosporin A therapy induces a decrease in glomerular filtrati on rate associated with increased reabsorption activity of proximal tu bular cells.