Acute kidney injury caused by consumption of melamine-contaminated infant formula in 47 children: a multi-institutional experience in diagnosis, treatment and follow-up.

Since the spring of 2008, an epidemic of urinary tract stones was noted among children in China. This is believed to be associated with consumption melamine-contaminated powdered formula. A few patients presented with acute kidney injury (AKI) due to bilateral renal or ureteral calculi requiring surgical intervention to relieve the obstruction. We retrospectively analyzed clinical and laboratory data, ultrasonograms and treatment methods in children with melamine-induced urolithiasis and AKI who were hospitalized at seven hospitals from September to November 2008 in Gansu Province, China. Treatment given included conservative treatment, cystoscopic or urethroscopic lithotripsy, retrograde ureteral catheterization, ureterolithotomy and nephrostomy. Patients were monitored postoperatively with data of ultrasonography, urinalysis and blood and urine biochemistry. The mean age of the 47 children was 10 months (mean ± SD, 10.83 ± 5.11 months). Thirty-four (72.34%) were male. Calculi size ranged from 3 to 14 mm in diameter. Nine patients (19.15%) were successfully treated with conservative treatment; 32 (68.09%) underwent retrograde ureteral catheterization and eight had simultaneous cystoscopic or urethroscopic stone removal; four were successfully treated with ureterolithotomy, and 1 underwent percutaneous nephrostomy. Thirty-eight patients were followed up for a mean ± SD of 18.50 ± 5.27 months and their renal functions were found to have completely recovered. Five (13.16%) cases had residual renal stones with diameter ranging from 2 to 4 mm. Therefore, this study has demonstrated that melamine-induced urolithiasis could lead to AKI. Removing obstruction promptly by surgical intervention has been found to be effective with satisfactory outcomes observed at mean follow-up period of 18-month. However, residual renal stone remained in 13.16% of the cases which required continued close observation.