RESUMO
BACKGROUND: Vitamin D deficiency is ubiquitous within the population of children. A similar problem is recognized among pediatric patients with acute lymphoblastic leukemia. The purpose of this study was to analyze the prevalence of vitamin D deficiency and to investigate the connection between vitamin D status and the course of induction treatment of ALL. MATERIALS AND METHODS: A cross-sectional study including 59 patients with newly diagnosed ALL from May 2017 until November 2020. RESULTS: Vitamin D deficiency was found in 39% of the patients. There were no seasonal differences in vitamin D status. Patients with optimal 25(OH)D concentration presented more profound thrombocytopenia ( P =0.015) and required more frequent platelet transfusions ( P =0.018). Good prognosis factors such as B phenotype and hyperdiploidy were also more frequent among children with higher 25(OH)D concentration ( P =0.01 and 0.014, respectively). CONCLUSIONS: The study showed that patients with a higher serum concentration of 25(OH)D presented deeper thrombocytopenia and needed more frequent transfusions. Moreover, those patients showed higher rates of B-cell leukemia and hyperdiploid karyotype. We did not find any influence of the possible exposure to sunlight (defined as the season of the year on admission) on serum 25(OH)D concentration, which supports the argument for supplementing vitamin D all year round. Moreover, the supplementing of vitamin D seems to be safe and does not cause any renal complications connected to calcium and phosphorus imbalance as no correlation between their levels and 25(OH)D concentration was found.