Endocrine Abstracts

Introduction: Fracture incidence is increased during and after treatment for childhood acute lymphoblastic leukaemia (ALL). Studies using DXA, which measures a composite of both trabecular and cortical bone mineral density (BMD), have shown reduced BMD during treatment. We therefore used peripheral quantitative computed tomography (pQCT) to investigate changes in compartmental (cortical and trabecular) volumetric BMD (vBMD) and bone geometry, and evaluated the influence of treatment factors, adiposity and adipokines on bone outcome.

Methods: Children undergoing treatment for ALL (n=49, 65% male, age 9.1±4.0 years) were compared to healthy controls (n=34, 50% male, age 9.9±3.7 years). Body composition was asessed by BMI and whole body DXA. pQCT scans were obtained at metaphyseal and diaphyseal sites of the radius and tibia. Blood samples were analysed for leptin, adiponectin and osteocalcin concentrations.

Results: Radial and tibial trabecular vBMD were reduced in subjects with ALL compared to controls (P<0.05) but cortical vBMD was unchanged. Tibial bone strength index (BSI), a measure of resistance to compressive forces, was lower in subjects with ALL (54.7±22.2 vs 82.5±27.8 mg/mm⁴, P<0.001). Subjects with ALL had greater BMI (0.83±1.18 SDS vs 0.17±0.99 SDS, P<0.01) and DXA-measured adiposity (32.2±7.6 vs 25.7±7.1%, P<0.001) than controls, but no relationships with vBMD or bone geometry were identified. Serum adipokines and osteocalcin were similar in patients and controls.

Conclusion: Selective reduction in trabecular vBMD with excess adiposity may predispose to increased bone fragility. Alterations in adipokines and osteocalcin were not identified as a contributory mechanism to altered bone structure. These findings may inform future choices for bone protective interventions during treatment for childhood ALL.