The clinical analysis of young children's urolithiasis due to melamine-tainted infant formula.

OBJECTIVE: To analyze etiology, clinical features, effective diagnostic methods and therapeutic efficacy of infant urolithiasis related to melamine.
METHODS: A total of 2,235 children fed with milk products were screened at the Second Hospital of Shandong University between 1st September and 31st December 2008. Of the children screened, 1,242 were male and 993 female, with a median age of 15 months (range 4-72 months). Among them, 182 with detailed data were enrolled and divided into Group 1 (calculus group, n = 79) and Group 2 (noncalculus group, n = 103) according to their results of the screening. All cases were reviewed with regard to melamine exposure, presentation, laboratory data, B-ultrasound findings and treatment efficacy.
RESULTS: Compared to 103 patients without stones, the 79 patients with stones confirmed by B-ultrasound had significant differences in: melamine daily intake (5.17 ± 4.53 vs. 2.38 ± 3.39 mg/kg per day, P < 0.001) and duration of problematic milk feeding (12.53 ± 8.47 vs. 8.65 ± 3.40 months, P < 0.001). Most of the patients in Group 1 (65.82%) were asymptomatic. In Group 1, all the patients with kidney stones less than 10 mm (n = 75) were successively treated conservatively, whereas the other four with kidney stones >10 mm required surgical treatment.
CONCLUSIONS: Melamine overdose can cause an increased risk of developing kidney stones in children. B-ultrasound is the first choice for the diagnosis of urolithiasis related to melamine. For most patients, the conservative treatment is effective; however, the patients with kidney stones >10 mm, surgery may be needed.