Importance of Adjusting Dual-energy X-Ray Output for Body Size

Abstract

We compared DXA whole body and lumbar spine bone mineral density (BMD) using manufacturers software with a body size correction which derived bone mineral content (BMC) for bone area in survivors of acute lymphoblastic leukemia in Saudi Arabia (n = 51, mean age 13.5 y). With no corrections, 29 patients (57%) had lumbar spine BMD Z score < -1.0 and 21 (41%) had whole body BMD Z score < -2. After correction, only 6 (12%) had lumbar spine BMC Z score < -1.0 and 4 (8%) had whole body BMC Z score < -2. Agreement between the methods was "poor" by weighted κ analysis.

In Response

“…Indeed, we consider our study on a sample of adolescent survivors of ALL2 to provide empirical support for the prediction made in a study by Webber et al3: interpreting dual energy x-ray (DXA) bone health data requires caution. In particular, failure to adjust DXA bone mineral density (BMD) data for body size risks erroneous judgments about bone health, which could be clinically important,3 particularly in children and adolescents with chronic disease 1,2.…”

“…In particular, failure to adjust DXA bone mineral density (BMD) data for body size risks erroneous judgments about bone health, which could be clinically important,3 particularly in children and adolescents with chronic disease 1,2. Although DXA is a valuable component of the assessment of bone health,4 and knowledge of the need to adjust BMD values appropriately for body size is increasing, this point is not as widely known as it should be at present 2. Barr1 also highlights the potentially valuable role for DXA in the assessment of body composition.…”

Measurement of Bone Mineral Density in Children With Cancer

“…The article by Aldhafiri et al1 raises several clinically relevant issues. As addressed in the principle objective given in the study, measurement of bone mineral density in children by dual-energy x-ray absorptiometry (DXA) requires adjustment for height and weight, therefore providing validation of our observations reported in 2009 2.…”