title: Maternal plasma osteoprotegerin concentration in normal pregnancy.
abstract: OBJECTIVE
  Pregnancy is associated with major changes in calcium metabolism because the neonatal skeleton contains approximately 30 g of calcium, which are largely deposited in the third trimester. Osteoprotegerin (OPG) acts as a decoy receptor for the "Receptor Activator of Nuclear Factor-kappaB Ligand" (RANKL), which is an essential factor for bone remodeling. This study was conducted to determine whether there were changes in maternal plasma OPG concentration during normal pregnancy.
  
  
  METHODS
  A cross-sectional study was performed in 433 patients of reproductive age (40 nonpregnant and 393 pregnant). Pregnant patients were classified into 4 groups according to gestational age: group 1: 11 to 14 weeks (n = 100); group 2: 15 to 18 weeks (n = 99); group 3: 27 to 30 weeks (n = 100); and group 4: 37 to 42 weeks (n = 94). Plasma OPG concentrations were measured with the use of a sensitive and specific immunoassay. Nonparametric statistics were used for analysis.
  
  
  RESULTS
  OPG was detected in the plasma of all women tested. The median OPG concentration was significantly higher in term patients than in those in early pregnancy (median: 6.63 pmol/L [range: 1.57-25.57] vs median: 3.98 pmol/L [range: 0.41-13.71], P < .001). There was no significant difference in plasma OPG concentrations between nonpregnant women and those in groups 1 or 2 (nonpregnant women median: 3.86 pmol/L [range: 1.64-15.29] vs group 1 median: 3.98 pmol/L [range: 0.41-13.71] vs group 2 median: 3.87 pmol/L [range: 1.14-69.83], P = .75).
  
  
  CONCLUSIONS
  The median maternal plasma OPG concentration is higher in the third trimester than in the first trimester of pregnancy. OPG may be involved in the regulation of bone turnover during pregnancy.
authors.affiliation: Perinatology Research Branch, National Institute of Child Health and Human Development, National Institutes of Health, Department of Health and Human Services, Bethesda, MD, USA.
authors.forename: Joon-Seok
authors.initials: JS
authors.lastname: Hong
authors.forename: Joaquin
authors.initials: J
authors.lastname: Santolaya-Forgas
authors.forename: Roberto
authors.initials: R
authors.lastname: Romero
authors.forename: Jimmy
authors.initials: J
authors.lastname: Espinoza
authors.forename: Luís F
authors.initials: LF
authors.lastname: Gonçalves
authors.forename: Yeon Mee
authors.initials: YM
authors.lastname: Kim
authors.forename: Samuel
authors.initials: S
authors.lastname: Edwin
authors.forename: Bo Hyun
authors.initials: BH
authors.lastname: Yoon
authors.forename: Jyh Kae
authors.initials: JK
authors.lastname: Nien
authors.forename: Sonia
authors.initials: S
authors.lastname: Hassan
authors.forename: Moshe
authors.initials: M
authors.lastname: Mazor
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D005260:Female; D005865:Gestational Age; D006023:Glycoproteins / Q000097:blood*; D006801:Humans; D053244:Osteoprotegerin; D011247:Pregnancy / Q000502:physiology*; D011261:Pregnancy Trimester, First; D011263:Pregnancy Trimester, Third; D018160:Receptors, Cytoplasmic and Nuclear / Q000097:blood*; D018124:Receptors, Tumor Necrosis Factor / Q000097:blood*
chemical_list: D006023:Glycoproteins; D053244:Osteoprotegerin; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; C506030:TNFRSF11B protein, human