Cystinuria: diagnosis and therapeutic approach

Cystinuria is an aminoaciduria due to the impairment of transport of cystine and dibasic amino acids (arginine, ornithine, and lysine) in the apical membrane of the intestinal epithelium and proximal renal tubule. The result is an absence of cystine reabsorption in the renal tubule producing an excess of cystine in urine and stone formation. Unlike the other stones, cystine stones are very difficult to eliminate with lithotripsy. Noninvasive therapy should therefore be used to prevent relapse in stone formation. This therapy is based on the use of high fluid intake, urine alkalinization, and chelating agents. In order to preserve renal function, a combination of these three therapeutic measures is necessary to produce a low recurrence and morbidity of the disease.