An uncommon cause of acute kidney injury in young children: cystinuria.

Bilateral obstructive nephrolithiasis is a rare cause of acute kidney injury (AKI) in early childhood. As soon as the identification of AKI secondary to ureteral stone is made, it will necessitate an emergency treatment. We report three infants with AKI caused by bilateral obstructive ureteral cystine stones. They were diagnosed with acute post-renal injury due to obstructive bilateral ureteral stones based on ultrasound scan findings. Immediately, bilateral ureteral stents were inserted for urinary drainage. Once renal function recovered to normal, each patient underwent ureteroscopy and percutaneous nephrolithotomy at the same session. Cystinuria was diagnosed by stone analysis and increased urinary excretion of cystine. Patients were advised to maintain a high fluid intake and were treated with potassium citrate in addition to tiopronin. With these three cases we would like to emphasize the importance of urolithiasis in the differential diagnosis of acute renal failure in young children, since urolithiasis may only cause nonspecific symptoms in this population. An early diagnosis with prompt treatment and a close follow-up are the key for achieving the best long-term outcome in cystinuria.