Prepubertal children with premature adrenarche had higher bone mineral
density when compared with healthy children in a new cross-sectional study.
However, bone size-adjusted BMD or height-adjusted BMD was not significantly
different between the two groups.
Researchers in Finland assessed whether BMD and body composition were
changed in 126 prepubertal children with (n=64; 10 boys) and without (n=62; 10
boys) premature adrenarche, and further assessed whether genetic variation in
LDL receptor-related protein 5 affected BMD in premature adrenarche.
Children were divided into three groups on the basis of physical
activity:
- Occasional or no physical activity in addition to school-based
physical education.
- Regular after-school physical activity.
- Participation in competitive sports or exercising daily.
Premature adrenarche vs. healthy controls
When compared with the control group, children with premature adrenarche
had higher femoral neck and lumbar spine BMD (z-score: 0.56 vs.
–0.09; P<.001 and 0.20 vs. –0.31; P=.009). After
adjustment for height or bone size, mean BMD was not significantly different
between the groups.
Femoral neck and BMD were significantly associated with height SD score
(R=0.43-0.45, R=0.62–0.63; P<.001). A moderate association was
observed with BMI SDS (R=0.29-0.39; P<.03).
Of the children with premature adrenarche, LRP5 single-nucleotide
polymorphism E644E minor variant was associated with lower BMD and F549F minor
variant was associated with higher BMD.
Height SD score (P=.002) and physical activity (P=.045)
were the only parameters independently associated with lumbar spine BMD in the
control group. However, height SDS (P<.001), age (P<.001)
and male sex(P=.036) were positively associated with femoral neck BMD.
“Our results indicate that growth in height and bone size, and to a
lesser extent body weight, are more important determinants of bone mass accrual
than increased circulating adrenal androgen concentrations in prepubertal
children,” the researchers concluded. “Genetic variation in
LRP5 may slightly contribute to BMD in prepubertal premature adrenarche
children.”
Utriainen P. J Clin Endocrinol Metab.
2009;94:4144-4151.