Diminished bone mineral density (BMD) is a known complication after bone marrow transplantation (BMT) in childhood 1–3. Endocrine dysfunction, irradiation, corticosteroids and chronic graft versus host disease (cGVHD) have been identified as risk factors for diminished BMD in childhood cancer survivor populations 4–9. To date a comprehensive understanding of the mechanisms and risks for diminished BMD after childhood BMT has not be described.
Measurement of BMD density in childhood cancer survivors has also been problematic. In children the World Health Organization (WHO) criteria are used for the clinical diagnosis of osteopenia/osteoporosis based on Z-scores calculated from age; sex; and race; matched reference data. Many childhood BMT survivors are small for age, making the standard Z-score comparisons based on age/sex alone inaccurate, systematically underestimating BMD in smaller children 10. Current recommendations suggest three dimensional (volumetric) measures of BMD should be used in this population 11.
Dual energy x-ray absorptiometry (DEXA) is the most frequently used technique to assess BMD; it is readily available and associated with very low exposure to ionizing radiation. DEXA acquires BMD measures in two dimensions, with calculation necessary to obtain volumetric measures 12. We identified no studies that compared the areal and calculated volumetric BMD measures from DEXA scans in childhood BMT survivors.
Maintenance of appropriate BMD is multi-factorial including the influence of other components of body composition, fat mass and fat-free mass. The associations between BMD and fat mass and fat-free mass vary according to the population studied but may explain up to 31% of the variance in BMD in healthy populations 13. We identified no studies that examined the associations between BMD and body composition in childhood BMT survivors. Knowledge of these associations may be important for understanding the BMD outcomes and may guide treatment decisions
The aims of this study were to describe the lumbar spine BMD of BMT survivors; compare the DEXA scan acquired areal and volumetric measures of BMD; explore the relationship between BMD measures and body composition; and identify disease and treatment factors that predict diminished BMD