The correlation between dual-energy X-ray absorptiometry measures of bone density in the proximal femur and lumbar spine of children.
OBJECTIVE
To assess the correlation between a pediatric patient's proximal femur and lumbar spine bone mineral density (BMD) Z-scores, and the side-to-side difference between proximal femurs.


METHODS
Three hundred and thirty-nine patients aged 2.2-17.0 years with an assortment of underlying conditions underwent dual-energy X-ray absorptiometry (DXA) measures of BMD in both proximal femurs and the lumbar spine.


RESULTS
Z-scores in the proximal femur and lumbar spine correlated highly (r = 0.73, P = 0.0001), but for individual patients the difference was often significant, and increased as BMD deviated further from normal. For patients with proximal femur Z-scores of 1 to -1 the mean difference between proximal femur and lumbar spine Z-scores was 0.5; with proximal femur Z-scores of less than -3 the mean difference was increased to 1.7. In conditions which symmetrically involve the lower extremities, the right and left proximal femur Z-scores differed on average by only 0.2.


CONCLUSIONS
BMD measurements for pediatric patients are most easily interpreted by clinicians if converted to Z-scores, yet these are usually available only for the lumbar spine. Age-normalized BMD assessment at more than one site is necessary to provide a more reliable, complete assessment of bone mineral status in pediatric patients.
Henderson
R C
RC
University of North Carolina, Chapel Hill 27599-7055, USA.
D015502:Absorptiometry, Photon; D000293:Adolescent; D015519:Bone Density; D002648:Child; D002675:Child, Preschool; D005269:Femur / Q000000981:diagnostic imaging*; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging*; D010024:Osteoporosis / Q000000981:diagnostic imaging; D012044:Regression Analysis