Intervention strategies for cystinuria: A systematic review

PurposeThis systematic review evaluates the current intervention strategies for cystinuria and assesses their quality and efficacy in order to determine the need to identify new and improved strategies for treatment.Materials and MethodsA literature search for interventions in cystinuria was conducted on key electronic databases for studies published between 1996 and 2019. Quality was assessed using Methodological Index for Non-Randomized Studies (MINORS). Studies meeting the inclusion criteria were assessed for study design, patient characteristics and outcomes of interventions, including urinary cystine levels, stone-free rate and stone recurrence rate. A qualitative and critical analysis was performed.ResultsCommon treatment strategies for cystinuria include hydration and diuresis, alkali therapy and thiol-based therapeutics. Conservative therapies such as adequate hydration and urinary alkalization effectively increased urinary pH, decreased urinary cystine levels and the formation of cystine stones. Second line agents reported included thiols such as Tiopronin, D-penicillamine and captopril. Non-invasive surgical procedures were found to reduce operative trauma and preserved renal function. Combined treatment approaches with hydration and thiols after surgical procedures were associated with less stones and reduced stone recurrence rates. Patient compliance to interventions was often poor and contributed to recurrent cystine stones.ConclusionsDespite existing pharmacological intervention strategies, cystinuria patients frequently require surgical procedures. A more detailed understanding of the mechanisms of pathogenesis of cystinuria as well as an evaluation of patients on an individual basis may be beneficial in reducing the severity of cystinuria, by reducing stone recurrence and associated renal complications.