EFFECT OF IRON ON BONE TISSUE METABOLISM AND THYROID FUNCTION IN CHILDREN LIVING ON RADIOLOGICALLY CONTAMINATED TERRITORIES SINCE THE ChNPP ACCIDENT.

Objective: To assess the metabolic processes in bone tissue and state of thyroid gland depending on iron metabolism parameters in children of pre-pubertal, pubertal and post-pubertal age, living on radiologically contaminated territories after the ChNPP accident.

Materials and methods: Children (n = 119) aged 6 to 18 years were examined and the 4 study groups were formed, featuring the childhood, pre-pubertal, pubertal and post-pubertal life periods. Clinical symptoms, iron metabolism parameters (serum iron (SI) and ferritin (SF) content, transferrin saturation coefficient), parameters of bone tissue metabolism (serum creatinine and alkaline phosphatase (APh)), and amino acid content in urine were taken into account. Functional state of thyroid, titers of antibodies to thyroperoxidase (TPOAb) and thyroglobulin (TgAb) were assayed. Results and their discussion are presented depending on the age of children, biochemical parameters of blood, iron metabolism findings, thyroid gland function and individualized radiation doses.

Results: In 13.4 % of pubertal and post-pubertal children an elevated content of SI and SF was observed. APh levels were increased in 20.2 % of children (758.9 ± 16.3 U/l) being directly correlated with SI levels (rs = 0.50; р < 0.01). In 16.3 % of children of pubertal and post-pubertal age, in whom the level of SI was above 27 μmol/l, a direct correlation with serum thyroid-stimulating hormone (TSH) level was established in case of the hormone content above 2.5 mU/l (rs = 0.50; р < 0.05). Serum creatinine level directly correlated with glycine content in urine (rs = 0.70), which is a part of collagen, and inversely correlated with serum APh (rs = -0.47), (р < 0.05). Under the levels of SI higher than (15.1 ± 1.2) μmol/l and SF higher than (87.5 ± 6.4) ng/ml, the TPOAb titer was higher than at lower iron concentrations (U-test = 64.5, р < 0.05). The TgAb titer directly correlated with SI (rs = 0.39) and TSH (rs = 0.81) levels (р < 0.01). The average effective radiation dose in children was (0.75 ± 0.10) mSv. A direct correlation was established between the child's radiation dose and age (rs = 0.33; р < 0.05).

Conclusions: Bone metabolism depends on the age of children, characteristics of pubertal period, excess of iron in the body, and functional state of thyroid system, which is involved in collagen formation and protein metabolism.