Endocrine Abstracts

Background: Reduced bone mineral density (BMD) z-scores from Dual energy X-Ray absorptiometry (DEXA) have been reported in childhood HSCT survivors. However, BMD z-scores are unreliable in patients with short stature.

Objective: To investigate the influence of HSCT/TBI on size-corrected BMD in childhood leukaemia survivors.

Method: Post-pubertal leukaemia survivors (16–26 years) treated with HSCT/TBI (10–14.4 Gy) (n=21, ten male) at mean aged 9.3 (1.0–10.8) years were compared with patients treated with chemotherapy-only (n=28, 11 male). All had had endocrine evaluations and were on replacement hormones where appropriate. No patients were on long-term steroid therapy. Assessments: anthropometry (height, weight), DEXA scanning (Lunar Prodigy fan beam) [BMD-z-scores, bone mineral content (BMC), bone area (BA)] and vitamin D levels. Size-corrected BMD [i.e. Bone Mineral Apparent Density (BMAD)] were represented as total-BMAD (BMAD_T)=BMC/total body BA^2/height and Lumbar spine-BMAD (BMAD_L2-4)=BMD_L2-4×[4/(π×width)]. Analysis: student’s t-tests and Pearson’s correlations (5% significance).

Results: HSCT/TBI compared with chemotherapy-only survivors had lower total BMD z-scores (−0.74 vs 0.19, P=0.012), but were lighter (P<0.001) and shorter (P<0.001). Total-BMD correlated positively with height-SDS, weight-SDS, fat and lean masses (all P<0.001). Size corrected BMD showed no mean(SD) differences between HSCT and chemotherapy-only patients: BMAD_T (0.089 (0.008) vs 0.086 (0.007), P=0.13); BMAD_L2-4 (0.38 (0.057) vs 0.37 (0.056), P=0.33). There were no relationships between BMAD_T or BMAD_L2–4 with age at or time from primary diagnosis in both groups; or with age at and time from HSCT/TBI in HSCT/TBI group. HSCT/TBI survivors showed no relationships between BMAD_T or BMAD_L2–4 with serum Vitamin D (P=0.13, P=0.21) or presence of endocrine disorders (growth hormone deficiency (P=0.16, P=0.46), hypothyroidism (P=0.53, P=0.58), gonadal failure (P=0.33, P=0.43)).

Conclusions: BMD must be corrected for size for appropriate interpretation to avoid over-diagnosis of osteopenia. Oncology treatment effects on long-term peak bone mass need further evaluation.