title: Melamine-induced urinary calculi in infants--sonographic manifestations and outcomes 1 year after exposure.
abstract: BACKGROUND
  In 2008, the melamine-tainted-milk incident started with reports of increased incidence of urolithiasis in infants in China. Affected children were screened for urolithiasis.
  
  
  OBJECTIVE
  The purpose of this study was to analyze sonographic characterization of infant melamine-induced urolithiasis.
  
  
  METHODS
  Transabdominal US examination was done in 603 infants with melamine-induced calculi. The imaging characteristics of calculi and hydronephrosis were analyzed. Follow-up US imaging was performed.
  
  
  RESULTS
  Comet-tail sign was seen behind the calculus of <4 mm. Calculi of ≥ 4 mm were found in 299 inpatients with clear posterior border and with or without light shadowing. Solitary and multiple stones had similar incidence. Incidence of calculi in the inferior renal calyx was the highest (55.2%) in inpatients. Calculus size in inpatients age 2-3 years was smaller than that of children younger than 2 years old (P < 0.05). Inpatients age 2-3 years had the highest incidence rate (48.0%) of hydronephrosis.
  
  
  CONCLUSIONS
  Calculi of <4 mm manifested as hyperechoic foci near the renal papillae, while calculi of ≥ 4 mm usually manifested as echogenic foci with visible inferior edge in the renal calyx. Hydronephrosis was a common imaging finding in inpatients ages 2-3 years.
authors.affiliation: Department of Medical Ultrasonics, The Second Hospital of LanZhou University, LanZhou, 730030, People's Republic of China. niefang028@yahoo.com.cn
authors.forename: Fang
authors.initials: F
authors.lastname: Nie
authors.forename: Xin-jie
authors.initials: XJ
authors.lastname: Li
authors.forename: Pan-feng
authors.initials: PF
authors.lastname: Shang
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000818:Animals; D002417:Cattle; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D005517:Foodborne Diseases / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D008892:Milk / Q000506:poisoning*; D018570:Risk Assessment; D014227:Triazines / Q000506:poisoning*; D014463:Ultrasonography / Q000706:statistics & numerical data*; D014545:Urinary Calculi / Q000139:chemically induced* / Q000000981:diagnostic imaging* / Q000453:epidemiology
chemical_list: D014227:Triazines; C011907:melamine