Conservative management of pediatric nephrolithiasis caused by melamine-contaminated milk powder

OBJECTIVE. In this article we report our experience with the diagnostic screening and management of children with melamine-induced nephrolithiasis. METHODS. A total of 1091 children younger than 4 years who had been exposed to melamine-contaminated formula from September 17 to October 12, 2008, were screened for nephrolithiasis at the department of pediatrics at Shenzhen Nanshan Hospital in China. During the clinical examination, each patient's demographic characteristics were recorded together with the details of his or her milk-consumption profile during the contamination scare and any clinical signs of poisoning. Urinary stones were detected by B-ultrasonography, and renal status was examined by a routine urine test panel and a renal function test. When urinary stones were detected, patients were ordered to cease consumption of the suspected formula, and a conservative treatment course was adopted, including infusion of fluids, urinary alkalinization, increased water consumption, and diuresis. RESULTS. Of the 1091 children screened, 12 (1.1%) were diagnosed with kidney stones. They had been exposed to the contaminated milk from 1 to 24 months. Eleven (91.7%) of these 12 patients had consumed milk with a high level of melamine content (955–2563 ppm); 1 patient (8.3%) had consumed milk with a low-level melamine content (6.2–17.0 ppm). Six patients exhibited dysuria; the remaining 6 patients were asymptomatic. All 12 patients had normal renal function, although 4 had proteinuria, and 1 had hematuria. The kidney stones were resolved within 3 to 5 days of commencing treatment in all 12 cases. CONCLUSIONS. Nephrolithiasis was associated with high melamine-exposure levels. A combination of B-ultrasonography and urinalysis is suitable for screening for pediatric nephrolithiasis caused by melamine poisoning. The condition can be resolved with a conservative treatment approach in patients without serious clinical symptoms who have normal kidney function.