PB1770: REASONS FOR CHANGES OF BONE FORMATION PROCESSES IN CHILDREN WITH ALL LIVING IN RADIOACTIVELY CONTAMINATED TERRITORIES OF UKRAINE

Abstract

Background: The state of bone structures, stromal microenvironment of the bone marrow and their hormonal regulation can be affected by iron metabolism. The mechanisms of increased bone density (IBD) in children with ALL deserve special attention. Aims: Identify the reasons of elevated bone density in children with ALL, who living in radiatioactively contaminated areas (RCA). Methods: 96 children aged 2 to 18 years with common-B ALL were examined after completion of maintenance therapy according to the protocol. The children lived at the RCA of Ukraine and were examined from 2012 to 2021. Data were studied in a comparative aspect in ALL children of 2 groups: Group I (n = 36) - with elevated IBD, above 100 units (117.4 ± 10.2 units), Group II (n = 60) - with standard IBD (100-85 units, 87.4 ± 9.1 units). Bone fractures in the anamnesis, dental caries, obesity, biochemical parameters of blood (amino acids in urine, serum ferritin (SF), serum alkaline phosphatase (AF), cholesterol, calcium, vitamin D, free thyroxine, thyroid-stimulating hormone, pituitary hormone, cortisol) as IBD were evaluated. The doses of bone marrow irradiation in patients according to their length of stay on RCA were calculated. Conducted statistical processing of materials (t-Student, Spearman’s correlation coefficient, U-Test). Results: The distribution of children by age in both groups did not differ. Boys (52 out of 60) predominated in Group I and in 30% of patients the levels of SF exceeded 500 ng / ml (728.8 ± 12.3 units). In children of both groups, a direct correlation was found between IBD and SF (p <0.001 and p <0.01, respectively). In children of Group I there was a direct relationship between IBD and fractures frequency (p <0,01). There were more children with low levels of total serum protein and glycine (p <0.01) in Group I, as number of children with high levels of alkaline phosphatase and cholesterol were less (p <0.05). IBD was inversely correlated with cortisol levels (rs = -0.73; p <0.001) and alkaline phosphatase activity (rs = -0.21; p <0.05). Dental caries in children in Group I was less frequent than in Group II (p <0.05). Survival of children was directly correlated with IBD (p <0.001). Irradiation doses in patients of Groups I and II ranged from 0.03 to 5.51 mSv (average 4.01 ± 0.17 mSv and 3.66 ± 0.18 mSv, respectively). In children, regardless of the surveillance group, there was a direct correlation between radiation dose, age of the child and the presence of obesity (p <0.001). Summary/Conclusion: The state of bone homeostasis in children with ALL depends on anabolic and catabolic metabolic processes that provide energy substrate for bone formation, the level of iron stores in the body and hormonal regulation.