title: Circulating levels of soluble alpha-Klotho are markedly elevated in human umbilical cord blood.
abstract: BACKGROUND
  Fetal serum levels of calcium and phosphate are higher than those in the maternal levels. Although α-Klotho is known to participate in calcium and phosphate metabolism in adults, its role in the perinatal period remains unknown.
  
  
  OBJECTIVE
  This study aimed to determine the baseline levels of soluble α-Klotho in fetuses and compare them with those in neonates, mothers, and adults to clarify whether α-Klotho is involved in the fetal-specific regulation of calcium and phosphate metabolism.
  
  
  METHODS
  We conducted a cross-sectional evaluation of healthy babies (at birth and/or at 4 d after birth), their mothers, and adult volunteers at one hospital.
  
  
  METHODS
  Twenty-one healthy mothers, their babies (23 in total, including two pairs of twins), and 25 adult volunteers participated in the study.
  
  
  METHODS
  We measured the serum levels of soluble α-Klotho and fibroblast growth factor 23 (FGF23).
  
  
  RESULTS
  In cord blood, the level of α-Klotho was markedly higher (3243 ± 1899 pg/ml) than levels in neonates at d 4 (582 ± 90 pg/ml), mothers (768 ± 261 pg/ml), and adult volunteers (681 ± 140 pg/ml) (P < 0.001), whereas the fetal level of FGF23 was lower than levels in the other subjects. The levels of soluble α-Klotho were negatively correlated with those of FGF23 in cord blood. Immunohistochemistry demonstrated that α-Klotho was predominantly expressed in syncytiotrophoblasts in normal term placenta.
  
  
  CONCLUSIONS
  Levels of soluble α-Klotho are markedly elevated in cord blood and might be useful as a biomarker for mineral metabolism in the fetus.
authors.affiliation: Department of Pediatrics, Osaka University Graduate School of Medicine, Suita 565-0871, Japan.
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Ohata
authors.forename: Hitomi
authors.initials: H
authors.lastname: Arahori
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Namba
authors.forename: Taichi
authors.initials: T
authors.lastname: Kitaoka
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Hirai
authors.forename: Kazuko
authors.initials: K
authors.lastname: Wada
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nakayama
authors.forename: Toshimi
authors.initials: T
authors.lastname: Michigami
authors.forename: Akihiro
authors.initials: A
authors.lastname: Imura
authors.forename: Yo-ichi
authors.initials: Y
authors.lastname: Nabeshima
authors.forename: Yuji
authors.initials: Y
authors.lastname: Yamazaki
authors.forename: Keiichi
authors.initials: K
authors.lastname: Ozono
mesh_terms: D000328:Adult; D000367:Age Factors; D000704:Analysis of Variance; D002118:Calcium / Q000097:blood; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005312:Fetal Blood; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood; D005966:Glucuronidase / Q000097:blood*; D006801:Humans; D007150:Immunohistochemistry; D007231:Infant, Newborn; D000090265:Klotho Proteins; D008297:Male; D008875:Middle Aged; D010710:Phosphates / Q000097:blood; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood
chemical_list: C000717427:FGF23 protein, human; D010710:Phosphates; D014807:Vitamin D; D005346:Fibroblast Growth Factors; D000089703:Fibroblast Growth Factor-23; C104450:25-hydroxyvitamin D; D005966:Glucuronidase; D000090265:Klotho Proteins; D002118:Calcium