Аim. Development of therapeutic and preventive measures (TPM) in children with acute leukemia in stages of chemotherapy and children with changes in bone tissue of density, taking into account the state of osteon, overload  iron in body, levels of thyroid hormones and cortisol.

Materials and methods. 175 children were examined: 110 patients with acute leukemia (AL) before the start of chemotherapy (CT) (I group) and after treatment (II group) and 65 children with changes in bone tissue density (BTD) (III group).

Pathology in pedigree, indicators of bone tissue metabolism (total protein, creatinine, alkaline phosphatase, calcium, vitamin D) were taken into account; serum iron (SI), ferritin (SF) and transferrin; levels of amino acids in urine, free thyroxine, pituitary thyroid-stimulating hormone (TSH), cortisol and  BTD. Results  were evaluated before and after TPM/

Results. Changes in osteon and hormonal status were determined in children with AL before the start of CT. CT aggravates protein deficiency, collagen catabolism, changes in bone tissue. After CT, content of SI and SF increased. 61.7% of children had overload iron. The SF level above 500 ng/ml in patients was more often accompanied by toxic hepatitis and death. In 23.6% of patients,  TSH level increased. A direct correlation established between level of TSH and oxyproline in urine (rs= 0.39), a direct correlation between SF and cortisol (rs = 0.55), which contributed to the degradation of collagen, changes in osteon and worse course of disease.Children with changes in bones more often had bone fractures, jaw abnormalities, hypermobility syndrome, increased levels of SI, and changes in hormonal regulation. Developed of TPM normalized indicators in most children after 1.5-3 months.

Conclusions. Study of changes in mechanisms of bone formation contributed to the timely diagnosis of pathology and implementation of pathogenetic therapy in both children with leukemia and children with changes in BTD.

Keywords: children, acute leukemia, osteon, regulation, treatment and prevention measures.