Bone loss during hematopoietic cell transplantation (HCT) in children

HCT may be deleterious to bone health and vitamin D status in children, but longitudinal studies are few. We conducted a multicenter, prospective cohort study to define time related changes in bone health markers during the first 100 days following allogeneic HCT in 26 children. Bone mineral density (BMD), bone mineral content (BMC), bone‐specific alkaline phosphatase (BSAP) and serum 25‐hydroxyvitamin D (25‐OHD) concentrations were measured at baseline, 30 days, and 100 days after HCT. Mean BMD and BMC Z‐scores (mean ± SD, −0.48 ± 1.09 and −0.59 ± 1.36, respectively) were normal at baseline. Repeated‐measures analysis revealed a 0.5 decline in BMD Z‐score (p<.0001) over the 100 day study period, when adjusted for age, sex, Tanner stage, lean mass, fat mass, resting energy expenditure, total energy intake, insulin sensitivity, and serum phosphorus. BMC and BSAP concentrations also declined significantly. Adjusted mean (SE) serum 25‐OHD concentrations declined from 30.1 ± 2.9 ng/ml at baseline, to 18.9 ± 2.0 ng/ml at 100 days after HCT. At 100 days after HSCT, 50% of patients were vitamin D deficient (serum 25‐ OHD <20 ng/ml). Significant bone loss and vitamin D deficiency occur in children in the first 100 days following allogeneic HCT. Strategies to attenuate acute bone loss in this setting are needed. Grant Funding Source : This project was supported by the Massachusetts Vitamin Litigation Grant and NIH grants M01‐ RR02172, UL1 RR025758–01, M01‐RR00865, M01‐RR00188, and K24 HD 058795.