Cystinuria Diagnosed at Age 67 Following a 49-Year Diagnostic Delay: A Reminder of Indolent Cystinuria in Adult Urolithiasis-A Case Report.

Cystinuria is a genetic disorder resulting from mutations in the SLC3A1 and SLC7A9 genes, which impair the reabsorption of cystine, ornithine, lysine and arginine and lead to increased urinary excretion of cystine. Elevated urinary cystine concentration promotes precipitation and subsequent stone formation, manifesting as recurrent urolithiasis. Cystinuria is the most common genetic condition that results in urolithiasis and is typically diagnosed in adolescence. In this case report, we present a male patient diagnosed with cystinuria at the age of 67. The patient presented with acute left flank pain, and noncontrast CT imaging of the urinary tract identified left renal calculi and multiple proximal ureteric stones, accompanied by hydronephrosis. Ureteroscopy revealed dense calculi resistant to laser fragmentation, and stone analysis confirmed a 100% cystine composition. The patient reported a previous stone event at age 18 with spontaneous passage but had remained stone-free for nearly 50 years and had no prior diagnosis of cystinuria. This case demonstrates that cystinuria, although typically diagnosed in childhood or adolescence, can be diagnosed in older adults with recurrent or resistant urolithiasis. Clinicians should maintain a high index of suspicion for cystinuria in adult patients with unexplained or refractory stone disease, and stone analysis remains essential for accurate diagnosis. Optimal management centres on preventing recurrent stone formation through aggressive fluid intake, dietary modifications and medical alkalinisation of urine. Multidisciplinary follow-up is important to reduce the risk of renal impairment and potential later need for nephrectomy.