Longitudinal tracking of dual-energy X-ray absorptiometry bone measures over 6 years in children and adolescents: persistence of low bone mass to maturity.
OBJECTIVE
Early assessment of bone mass may be useful for predicting future osteoporosis risk if bone measures "track" during growth. This prospective longitudinal multicenter study examined tracking of bone measures in children and adolescents over 6 years to sexual and skeletal maturity.


METHODS
A total of 240 healthy male and 293 healthy female patients, ages 6-17 years, underwent yearly evaluations of height, weight, body mass index, skeletal age, Tanner stage, and dual-energy x-ray absorptiometry (DXA) bone measurements of the whole body, spine, hip, and forearm for 6 years. All subjects were sexually and skeletally mature at final follow-up. Correlation was performed between baseline and 6-year follow-up measures, and change in DXA Z-scores was examined for subjects who had baseline Z < -1.5.


RESULTS
DXA Z-scores (r = 0.66-0.87) had similar tracking to anthropometric measures (r = 0.64-0.74). Tracking was stronger for bone mineral density compared with bone mineral content and for girls compared with boys. Tracking was weakest during mid- to late puberty but improved when Z-scores were adjusted for height. Almost all subjects with baseline Z < -1.5 had final Z-scores below average, with the majority remaining less than -1.0.


CONCLUSIONS
Bone status during childhood is a strong predictor of bone status in young adulthood, when peak bone mass is achieved. This suggests that bone mass measurements in children and adolescents may be useful for early identification of individuals at risk for osteoporosis later in life.
Children's Hospital Los Angeles, Los Angeles, CA. Electronic address: twren@chla.usc.edu.
Tishya A L
TA
Wren
Cincinnati Children's Hospital Medical Center, Cincinnati, OH.
Heidi J
HJ
Kalkwarf
Children's Hospital of Philadelphia, Philadelphia, PA.
Babette S
BS
Zemel
Creighton University, Omaha, NE.
Joan M
JM
Lappe
Columbia University, New York, NY.
Sharon
S
Oberfield
University of California, San Francisco, San Francisco, CA.
John A
JA
Shepherd
National Institute of Child Health and Human Development, Bethesda, MD.
Karen K
KK
Winer
Children's Hospital Los Angeles, Los Angeles, CA.
Vicente
V
Gilsanz
D015502:Absorptiometry, Photon; D000293:Adolescent; D000367:Age Factors; D000886:Anthropometry; D001827:Body Height; D001835:Body Weight; D015519:Bone Density / Q000502:physiology*; D002648:Child; D002657:Child Development / Q000502:physiology*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D010024:Osteoporosis / Q000000981:diagnostic imaging / Q000517:prevention & control; D011237:Predictive Value of Tests; D012016:Reference Values; D012737:Sex Factors