Background: Intrauterine growth restriction (IUGR) has been associated
with low bone mass in infancy and increased risk for osteoporosis
development in adult life. Osteoprotegerin (OPG) and receptor activator
of nuclear factor-kappa B ligand (RANKL) are main determinants of bone
resorption. Objectives: To investigate OPG and soluble RANKL (sRANKL)
concentrations in maternal, fetal and neonatal serum of IUGR patients
and appropriate for gestational age (AGA) pregnancies. Additionally,
plasma intact parathormone (PTH) concentrations were evaluated. Methods:
Circulating OPG, sRANKL and PTH concentrations were measured in 40
mothers and their singleton full-term fetuses-neonates (AGA: n = 20, and
IUGR: n = 20) on postnatal days 1 (N1) and 4 (N4). Results: No
significant differences in OPG, sRANKL or PTH concentrations were
observed between AGA and IUGR groups. In both groups, maternal OPG
concentrations were elevated compared with fetal, and N1 and N4
concentrations (p <= 0.045 in all cases). N4 sRANKL concentrations were
elevated compared with maternal, fetal and N1 ones (p <= 0.01 in all
cases). Fetal and N1 sRANKL concentrations correlated positively with
PTH levels (r = 0.642, p = 0.024 and r = 0.584, p = 0.046,
respectively). Conclusions: The lack of a difference in circulating OPG,
sRANKL or PTH concentrations between IUGR cases and AGA controls
suggests that the low bone mass of IUGR infants may not be related to
higher bone resorption rates. The increased maternal, compared with
fetal/neonatal, OPG concentrations may suggest their placental origin.
The lower OPG and higher sRANKL concentrations in fetuses and neonates
could represent high bone resorption rates. Copyright (C) 2009 S. Karger
AG, Base