title: Factors associated with serum CA19-9 levels among healthy children: a cross-sectional study.
abstract: BACKGROUND
  CA19-9 is a tumor marker mainly used for biliary tract, pancreas and colorectum. Since the marker applies usually for adults, the normal range of serum CA19-9 among children has been rarely reported. This is the first study reporting the distribution of serum CA19-9 levels among cancer-free children as well as their parents, taking into account the Lewis and secretor gene polymorphism and physical growth.
  
  
  METHODS
  Study subjects were 972 apparently healthy Japanese Brazilians including 476 children aged from 1 to 19 years.
  
  
  RESULTS
  The comparisons in five-year age groups demonstrated that the mean values of serum CA19-9 was lower in the boys than in the girls, and higher in younger age groups; 22.5 U/ml for 1-4 year-old (n=13), 17.4 U/ml for 5-9 year-old (n=36), 15.5 U/ml for 10-14 year-old (n=96) and 10.2 U/ml for 15-19 year-old (n=74) in boys, and 25.3 U/ml (n=11), 27.1 U/ml (n=50), 17.7 U/ml (n=105) and 13.5 U/ml (n=59) in girls, respectively. The difference in those geometric means was statistically significant among four age groups (p=0.006, ANOVA adjusted for sex). After Lewis and secretor genotypes, which are definitive factors of serum CA19-9, were taken into account, geometric mean of serum CA19-9 was associated with any of BMI (p<0.001), height (p<0.001) and weight (p<0.001) among children excluding those with le/le genotype. The associations were still significant when age was adjusted.
  
  
  CONCLUSIONS
  Serum CA19-9 values were higher among children than among adults, and influenced by sex, height, weight, and BMI even after the adjustment for age as well as Le and Se genotypes.
authors.affiliation: Department of Preventive Medicine, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Japan.
authors.forename: Sayo
authors.initials: S
authors.lastname: Kawai
authors.affiliation: Laboratory of Molecular and Cellular Biology, Department of Neurology, School of Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Sueli M
authors.initials: SM
authors.lastname: Oba-Shinjo
authors.affiliation: Japanese Brazilian Health Professional Volunteer Group, São Paulo, Brazil.
authors.forename: Lucy S
authors.initials: LS
authors.lastname: Ito
authors.affiliation: Laboratory of Molecular and Cellular Biology, Department of Neurology, School of Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Miyuki
authors.initials: M
authors.lastname: Uno
authors.affiliation: Laboratory of Molecular and Cellular Biology, Department of Neurology, School of Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Suely K N
authors.initials: SKN
authors.lastname: Marie
authors.affiliation: Department of Preventive Medicine, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Hamajima