Prim Care Companion J Clin Psychiatry 2007;9:244-249
© Copyright 2014 Physicians Postgraduate Press, Inc.
During adolescence, bone formation prevails over resorption, and
accumulation of 40% of peak bone mass ensues throughout this time period.
Multiple studies have explored bone mass accrual during the early stages of puberty,
but less is understood concerning factors that may affect bone accrual during
later years of adolescence. This cross-sectional study analyzed relationships
among bone mineral density (BMD) and demographic characteristics, behavioral
variables, and bone metabolism markers in postmenarchal adolescent girls.
Method: The cohort comprised 389 healthy postmenarchal adolescent girls,
aged 11 to 18 years, who were recruited into a prospective study of the effect of
depot medroxyprogesterone acetate (DMPA) on bone health in adolescents. Investigators
gathered demographic, reproductive health, and lifestyle data and
performed a complete physical examination at baseline. Body mass index (BMI)
was calculated. BMD at the lumbar spine, total hip, and femoral neck was measured
by dual-energy X-ray absorptiometry (DXA), and markers of bone metabolism
(serum bone-specific alkaline phosphatase [BAP], serum osteocalcin,
and urinary N-telopeptide [uNTX]) were measured prior to the study initiation.
The baseline data from this study were examined to assess potential correlates
of BMD in postmenarchal adolescent girls. Possible associations between
BMD values and other parameters were evaluated by analysis of variance and
Pearson’s correlation coefficient.
Results: Subjects who entered the study had a mean (± SD) chronological
age of 14.9 ± 1.7 years (range, 11–18), gynecologic age of 39.9 ± 23.0 months
(range, 1–120) postmenarche, and BMI of 23.5 ± 4.6 kg/m2 (range, 16.0–42.2).
Racial/ethnic distribution was 46% African American, 35% Caucasian, and 19%
other races; 9% had been pregnant. Positive correlations were observed between
lumbar spine BMD and chronological age (r = .301, p < .0001), gynecologic age
(r = .349, p < .0001), and BMI (r = .371, p < .0001). Total hip and femoral neck
BMD values were significantly higher (p < .05 and p < .05, respectively) in African
American subjects relative to non–African American subjects. A history of
pregnancy was significantly associated with a lower BMD at the lumbar spine
(p < .0001) and the total hip (p < .01) relative to the BMD of adolescents who
had never been pregnant. Alcohol use and cigarette smoking were not associated
with significant differences in BMD. Negative correlations were seen between
gynecologic age and the levels of BAP (r = –.564, p < .0001), osteocalcin (r =
–.349, p < .0001), and uNTX (r = –.281, p < .0001), and between lumbar spine
BMD and BAP (r = –.363, p < .0001), osteocalcin (r = –.129, p < .05), and
uNTX (r = –.202, p < .001) levels.
Conclusions: According to our data, in postmenarchal adolescent girls,
chronological age, gynecologic age, race/ethnicity, BMI, and previous history
of pregnancy are markedly associated with BMD. Bone accretion in the
postmenarchal years continues as bone turnover slows during this time period.