Severe hypercholesterolemia inhibits cyclosporin A efficacy in a dose-dependent manner in children with nephrotic syndrome.

In order to identify possible markers of cyclosporin A (CSA) efficacy, the use of CSA (6 mg/kg) in 47 children with refractory nephrotic syndrome was reviewed. Response was defined as remission of proteinuria within 2 months. Before CSA administration, nonresponders (N = 13) were found to have more proteinuria (6 versus 3 g/24 h; P less than 0.03) and higher serum creatinine levels (0.9 versus 0.6 mg/dL; P less than 0.03) compared with responders (N = 34). Also, a markedly elevated serum cholesterol level (545 versus 312 mg/dL; P less than 0.001) was noted among nonresponders. Logistic regression analysis of all three parameters isolated serum cholesterol (P less than 0.01) as the only significant predictor of CSA nonresponsiveness. Discriminate analysis identified serum cholesterol to predict 97% of responders and 77% of nonresponders (P less than 0.0005) to conventional CSA doses. The CSA whole-blood trough HPLC levels were subtherapeutic among nonresponders (71 ng/mL) compared with responders (162 ng/mL) (P less than 0.001). Thus, a high serum cholesterol level may prevent the achievement of therapeutic CSA blood levels with conventional doses. On the basis of this, seven of the nonresponders were re-treated by titration of the CSA dose (10 to 14 mg/kg) with their serum cholesterol level. Their mean highest trough CSA level was 286 ng/mL. Five patients responded within 2 months. No elevation in serum creatinine or evidence of nephrotoxicity on repeat biopsy was seen after 2 months of therapy in all seven patients. It was concluded that severe hypercholesterolemia in nephrotic syndrome patients necessitates the titration of the CSA dose with the serum cholesterol level to achieve remission.