Prospective Study of Changes in Bone Mineral Density and Turnover in Children after Hematopoietic Cell Transplantation.

Osteoporosis is common in adults after hematopoietic cell transplantation (HCT). The data on bone mineral density (BMD) in children after HCT are limited. The goals of this prospective study were to determine the incidence, timing, magnitude and possible predictors of bone loss in children following HCT. The study population included 49 patients (age 5–18 years) who were eligible to receive HCT at the University of Minnesota. The patients were evaluated at baseline, 100 days, 6 months, and 1 year after HCT. Lumbar BMD (BMDL) was assessed by dual-energy x-ray absorptiometry. The number of patients with osteopenia increased from 18% at baseline to 33% one year after HCT, and with osteoporosis from 16% to 19%. Mean areal BMDL z-score decreased from −0.56 to −1.1 by 6 months and at 1 year was −0.94, which was significant compared to standard normal distribution (p=0.004 and p=0.022, respectively). The absolute loss of bone mineral corresponded to 5.3% reduction in areal BMDL and 4.8% reduction in volumetric BMDL. The level of bone-specific alkaline phosphatase decreased by 30% by day 100 (p=0.009), followed by recovery toward baseline by 6 months. The level of osteocalcin >6.5 ng/mL at day 100 predicted recovery from the initial bone loss by 1 year. A reduction in BMDL at 6 months correlated with a cumulative dose of glucocorticoids. In conclusion, this study demonstrates that bone loss is common in children after HCT and is primarily due to suppression of bone formation. Further studies are necessary to validate osteocalcin as a predictive biomarker.