title: Melamine-contaminated powdered formula and urolithiasis in young children.
abstract: BACKGROUND
  A recent epidemic of melamine contamination of baby formula in China has been associated with the development of urinary tract stones, though the clinical manifestations and predisposing factors are incompletely delineated.
  
  
  METHODS
  We administered a questionnaire to the parents of children 36 months of age or younger who were being screened for a history of exposure to melamine and symptoms of, and possible predisposing factors for, urinary tract stones. In addition, we performed urinalysis, renal-function and liver-function tests, urinary tests for biochemical markers and the calcium:creatinine ratio, and ultrasonography. Powdered-milk infant formulas were classified as having a high melamine content (>500 ppm), a moderate melamine content (<150 ppm), or no melamine (0 ppm); no formulas contained between 150 and 500 ppm of melamine.
  
  
  RESULTS
  Contaminated formula was ingested by 421 of 589 children. Fifty had urinary stones, including 8 who had not received melamine-contaminated formula; 112 were suspected to have stones; and 427 had no stones. Among children with stones, 5.9% had hematuria and 2.9% had leukocyturia, percentages that did not differ significantly from those among children who were suspected to have stones or those who did not have stones. Serum creatinine, urea nitrogen, and alanine aminotransferase levels were normal in the 22 children with stones who were tested. Four of the 41 children (9.8%) who had stones and in whom urinary markers of glomerular function were measured had evidence of abnormalities; none had tubular dysfunction. Children exposed to high-melamine formula were 7.0 times as likely to have stones as those exposed to no-melamine formula. Preterm infants were 4.5 times as likely to have stones as term infants.
  
  
  CONCLUSIONS
  Prematurity and exposure to melamine-contaminated formula were associated with urinary stones. Affected children lacked typical signs and symptoms of urolithiasis.
authors.affiliation: Peking University First Hospital, Beijing, China.
authors.forename: Na
authors.initials: N
authors.lastname: Guan
authors.forename: Qingfeng
authors.initials: Q
authors.lastname: Fan
authors.forename: Jie
authors.initials: J
authors.lastname: Ding
authors.forename: Yiming
authors.initials: Y
authors.lastname: Zhao
authors.forename: Jingqiao
authors.initials: J
authors.lastname: Lu
authors.forename: Yi
authors.initials: Y
authors.lastname: Ai
authors.forename: Guobin
authors.initials: G
authors.lastname: Xu
authors.forename: Sainan
authors.initials: S
authors.lastname: Zhu
authors.forename: Chen
authors.initials: C
authors.lastname: Yao
authors.forename: Lina
authors.initials: L
authors.lastname: Jiang
authors.forename: Jing
authors.initials: J
authors.lastname: Miao
authors.forename: Han
authors.initials: H
authors.lastname: Zhang
authors.forename: Dan
authors.initials: D
authors.lastname: Zhao
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Liu
authors.forename: Yong
authors.initials: Y
authors.lastname: Yao
mesh_terms: D016009:Chi-Square Distribution; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D005506:Food Contamination; D006801:Humans; D007223:Infant; D041943:Infant Formula / Q000737:chemistry*; D007231:Infant, Newborn; D007234:Infant, Premature; D016015:Logistic Models; D008297:Male; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014227:Triazines / Q000009:adverse effects* / Q000032:analysis; D014463:Ultrasonography; D014545:Urinary Calculi / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology; D014551:Urinary Tract / Q000000981:diagnostic imaging; D052878:Urolithiasis / Q000000981:diagnostic imaging / Q000209:etiology*
chemical_list: D014227:Triazines; C011907:melamine