In this context, the exploration of vitamin D [25(OH)D] levels and the impact of the administration of corticoids on the RANKL/OPG ratio in pediatric patients with ALL is relevant, as an imbalance in the expression or function of any component of this system can induce deregulation of the remodeling cycle and generate modifications in BMD. The gene discussed is TNFSF11; the disease is acute lymphoblastic leukemia.