title: Outcome of children with melamine-induced urolithiasis: results of a two-year follow-up.
abstract: OBJECTIVE
  Our purpose is to describe the characteristics and the outcome of melamine-induced renal and urinary tract injury in young children who consumed melamine-contaminated infant formula.
  
  
  METHODS
  This is a descriptive longitudinal study over 2 years in 240 children with melamine-induced urolithiasis screened in our hospital from September 15 to October 31, 2008. Ultrasonography and serum creatinine (SCr), urea, β2-microglobulin (MG), cystatin C (Cys C), urinary Cr (UCr), microalbumin (mALB), α1-MG, β2-MG, n-acetyl-β-d-glucosaminidase (NAG) and retinol-binding protein (RBP) measurements were performed.
  
  
  RESULTS
  The children ranged in age from 1 to 82 months, and 145 were males. The largest calculus was 33 mm in diameter. X-ray diffraction pattern of the calculi displayed two diffraction peaks at 10.9° and 27.7° (2θ). Surgical management was performed in 14 patients. In 226 patients without surgical management, the calculi were passed in 59.63% patients within 1 month, in 85.40% within 6 and in 91.15% within 24 months. Increased SCr and urea levels were noted in three and six patients, respectively, at the time of diagnosis. The SCr, serum β2-MG, and Cys C levels at the time of diagnosis were higher than those at 3 and 6 months after diagnosis (P < 0.05, respectively). The levels of mALB/UCr, NAG/UCr, and RBP/UCr at the time of diagnosis were higher than those at 3, 6, 12, and 24 months after diagnosis (P < 0.05, respectively). α1-MG/UCr and β2-MG/UCr levels at the time of diagnosis were similar to those at 3 months after diagnosis, and significantly higher than those in the follow-up period (P < 0.05, respectively).
  
  
  CONCLUSIONS
  Melamine might injure both the renal glomerulus and the tubule, and that the predominant lesion is urolithiasis. The compositions of melamine-induced urolithiasis are melamine and cyanuric acid crystals. The urolithiasis might persist for over 2 years and cause irreversible damage. Therefore, a long-term follow-up for all patients is required.
authors.affiliation: Department of Medicine, the Children's Hospital of Zhejiang University School of Medicine and Key Laboratory of Reproductive Genetics (Zhejiang University), Ministry of Education, Hangzhou, P. R. China.
authors.forename: Chao Chun
authors.initials: CC
authors.lastname: Zou
authors.forename: Xiao Yang
authors.initials: XY
authors.lastname: Chen
authors.forename: Zheng Yan
authors.initials: ZY
authors.lastname: Zhao
authors.forename: Wei Fang
authors.initials: WF
authors.lastname: Zhang
authors.forename: Qiang
authors.initials: Q
authors.lastname: Shu
authors.forename: Jin Hu
authors.initials: JH
authors.lastname: Wang
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Shou Jiang
authors.initials: SJ
authors.lastname: Huang
authors.forename: Li Li
authors.initials: LL
authors.lastname: Yang
mesh_terms: D001806:Blood Urea Nitrogen; D002675:Child, Preschool; D003404:Creatinine / Q000097:blood / Q000652:urine; D055316:Cystatin C / Q000097:blood; D005260:Female; D005506:Food Contamination / Q000032:analysis; D006801:Humans; D007223:Infant; D041943:Infant Formula / Q000737:chemistry; D007231:Infant, Newborn; D008297:Male; D008855:Microscopy, Electron, Scanning; D012117:Resins, Synthetic / Q000009:adverse effects*; D014227:Triazines / Q000009:adverse effects*; D014463:Ultrasonography; D052878:Urolithiasis / Q000139:chemically induced* / Q000000981:diagnostic imaging / Q000601:surgery; D014961:X-Ray Diffraction; D001613:beta 2-Microglobulin / Q000097:blood
chemical_list: D055316:Cystatin C; D012117:Resins, Synthetic; D014227:Triazines; D001613:beta 2-Microglobulin; D003404:Creatinine; C011907:melamine