N Acetyl Cysteine for Cystinosis Patients

This study intends to verify the interference of N acetyl cysteine in the progression of chronic kidney disease in patients with Nephropathic Cystinosis.

Patients with Nephropathic Cystinosis have an increased oxidative stress and go to end-stage renal disease, even when all steps of the treatment are done. Therefore, this study is conducted to verify the interference of the stress oxidative in the progression of the renal disease with the use of an oxidant drug, N acetyl cysteine (NAC). The investigators selected patients with good compliance of the treatment. In these patients the investigators evaluate the serum creatinine, creatinine clearance estimated by Schwartz Formula, cystatin C and a marker of oxidative stress, TBARS ( thiobarbituric acid substances). The variables are analyzed 6 months before the introduction of NAC and the three months after NAC.