Bone mineral density after bone marrow transplantation in childhood: measurement and associations

This study examined the bone mineral density (BMD) of 46 (median age 16.3, 8-29) survivors of autologous and allogeneic bone marrow transplantation (BMT). Areal (g/m2) BMD was acquired with dual energy x-ray absorptiometry and volumetric (g/cm3) BMD values were calculated. Abnormal BMD was identified in 24% (11/46) of survivors with areal measures and 22% (10/46) with volumetric measures. Comparison of areal and volumetric BMD revealed the measures were highly correlated (r = 0.73, p<0.001) but clinical diagnosis of osteopenia/osteoporosis were not consistent. Volumetric z-scores were higher for 7/8 of the survivors who were < 3rd percentile for height. Associations of BMD and body composition and disease and treatment factors were assessed with multiple linear regression. When controlling for other significant associations and cumulative steroid dose, the body composition measure of fat mass index (FMI) was associated with higher volumetric BMD z-scores (CI: 0.006, 0.193; p = 0.037). CNS irradiation (CI: -1.710,-0.200; p = 0.015), age at time of testing (CI: -0.116, -0.024; p = 0.004) and female sex (CI: -1.375, -0.155; p = 0.015) were associated with lower volumetric BMD z-scores.

Childhood BMT survivors are at risk for diminished BMD. Areal and volumetric DEXA derived measures of BMD are highly correlated and volumetric measures may correct for underestimation of BMD in BMT survivors who are small for age. Survivors who received CNS irradiation, are older and female may be at greater risk for diminished BMD while fat mass is associated with higher BMD in childhood BMT survivors.