LAUSR

PURPOSE Cystinuria is a genetic disorder with both autosomal recessive or incompletely dominant inheritance. The disorder disrupts cystine and other dibasic amino acid transport in the proximal tubules of the kidney resulting in recurrent kidney stone formation. Currently, there are no consensus guidelines on the evaluation and management of this disease. This manuscript represents the consensus of the author panel and will provide clinicians with a stepwise framework for the evaluation and clinical management of patients with cystinuria based on evidence in the existing literature. MATERIALS AND METHODS A search of MEDLINE®/Pubmed® and the Cochrane database was performed using the key words "cystine nephrolithiasis," "cystinuria," "penicillamine, cystine," and "tiopronin, cystine." In total, as of May 2018 these searches yielded 2335 articles, which were then evaluated for their relevance to the topic of evaluation and management of cystinuria. Evidence was evaluated by the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system. RESULTS Twenty-five articles on the topic of cystinuria or cystine nephrolithiasis were deemed suitable for inclusion in this manuscript. The literature supports a logical evaluation process and step-wise treatment approach beginning with conservative measures: fluid intake and dietary modification. If stone formation recurs, proceed to pharmacotherapeutic options by first alkalinizing the urine and then using cystine-binding thiol drugs. CONCLUSIONS The proposed clinical pathways provide a framework for the efficient evaluation and treatment of patients with cystinuria that should improve overall outcomes of this rare, but highly recurrent form of nephrolithiasis.