Successful treatment of homozygous cystinuria with captopril

ABSTRACT

Cystinuria is an autosomal recessive hereditary disorder associated with nephrolithiasis and its attendant complications. Traditional management using oral alkali, D-penicillamine, or mercaptopropionyglycine in an attempt to increase urinary cystine solubility is often unsuccessful due to intolerable side-effects. The aim of this study was to determine, if captopril could reduce urninary cystine excretion in homozygous cystinuric patients. Three cystinuric patients with a history of multiple cystine stones despite previous traditional therapy were treated with 150 mg captopril daily for 3 years after determination of their baseline 24-hour urine cystine excretion. Cystine excretion studies were repeated subsequently at 6-month intervals. The baseline 24-hour urine cystine excretion was within the expected limits for homozygous cystinuria in all patients [1072, 962 and 959 mg cystine per gm creatinine per 24 hours]. After institution of captopril treatment, all patients had a significant decrease in urinary cystine levels [374,313 and 451 mg cystine per gm creatinine per 24 hours]. No patient experienced recurrent nephrolithiasis or adverse drug effects. We conclude that captopril can significantly decrease urinary cystine excretion in patients with homozygous cystinuria. Captopril should be considered an alternative to traditional drug management of cystinuria