Nagwa Abdallah Ismail leukemia disease (ALL) at completion of chemo- therapy and in long-term survivors of childhood ALL [21-23]. The bone loss caused by immobilization could partly explain the finding of a reduction in femoral BMD in children with cancer. The loss of bone during immobilization has been found to be greater in weight-bearing bones and to be more pronounced in younger patients [24]. In cortical bone, immobilization induced bone loss has been shown to become conspicuous after 3-6 months of inactivation [24]. Pathological fractures, predominantly in the femur, and osteoporosis after immobilization have been observed in children with cerebral palsy [25]. According to our results and others [5, 26, 27] a follow-up of both lumbar and femoral BMD is required to further evaluate the development of BMD in these children during their entire treatment. Scanning the femoral neck in children, however, is difficult because the skeletal landmarks may not be well developed and the femoral neck may be too small for the standard software. These factors contribute to poorer precision in this region. Additionally, there are few paediatric reference data for this site. The femoral neck region is not recommended in very young children because its changing shape makes longitudinal studies difficult and unreliable [28, 29]. In conclusion, we identified significant reductions in both lumbar and femoral BMDs in children with chronic medical conditions that might affect bone health. For this reason we recommend that, when technically feasible and there is no facility to measure TBLH, all patients should have spine and femoral neck bone mineral density measurements to avoid under-diagnosis of low bone mineral density being a risk for fractures in subjects with chronic medical conditions that might affect bone health. R e f e r e n c e s 1. 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