Conservative treatment of bone tissue metabolic disorders among patients with vitamin D-dependent rickets type II with genetic abnormality of type I collagen formation
Background. The purpose of the article is to determine the effect of conservative therapy on genetically caused disorders of bone tissue metabolism in patients with vitamin D-dependent rickets type II and genetic abnormality of type I collagen formation (VDDR(COL1)). Materials and methods. At the premises of consulting and outpatient department of SI “Institute of Traumatology and Orthopaedics of the NAMS of Ukraine”, 13 patients having VDDR type II and genetic damage of type I collagen formation were examined and treated. The medical treatment was conducted in four stages. The first stage included full examination of patients (calcium and phosphorus levels in the blood serum and their urinary excretion, as well as determination of calcidiol and calcitriol serum levels, indicators of parathyroid hormone and osteocalcin, and a marker of bone formation P1NP and osteoresorption b-CTx). At this stage, children were obligated to undergo a genetic test to detect changes (polymorphism) in alleles of receptors to vitamin D and type I collagen. Besides genetic tests, examinations at the other stages were conducted in full. Results. The study has shown the following. The genetically caused abnormality of reception to vitamin D results into substantial accumulation of vitamin D active metabolite in the blood serum. When combined with genetic abnormality of type I collagen formation, it significantly affected bone formation and destruction processes that causes development of osteomalacia (parathormone — vitamin D — osteocalcin system). The comprehensive study of vitamin D metabolism and biochemical vitals of bone tissue in patients having VDDR (COL1) brought us to understanding of some issues related to pathogenesis and nature of osteomalacia and, in future, osteoporotic changes on different levels, ensured us to express these changes by corresponding indices in the biochemical research and, finally, to develop appropriate schemes for the treatment of bone metabolism abnormalities existing at this disease. Conclusions. The impaired reception to calcitriol, when combined with genetic abnormality of type I collagen formation, shows the most serious bone tissue metabolism disorders in patients with vitamin D-dependent rickets, that further causes bone metabolism acceleration and osteomalation progression in the body of a growing child, as well as substantial acceleration of bone tissue resorption. In our opinion, the cause of the aforesaid phenomenon is formation of compromised collagen, which the child’s organism tries to rebuild; however, this assumption requires further study.
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