The effect of exogenous and genetic factors on a decrease in bone mineral density in children with cystic fibrosis

Osteoporosis is acomplication of cystic fibrosis, the relevance of studying which is associated with an increase in the life expectancy of patients and an increase in the proportion of adults in the general patient population. The aim of the research is to study exogenous and genetic factors of bone mineral density reduction in patients with cystic fibrosis and healthy children. Methods. 100 children with cystic fibrosis and 61 healthy children over 6 years old were examined. All children underwent X-ray densitometry with the DEXXUM device (South Korea). Vitamin D intake, dietary calcium intake and physical activity were assessed using aquestionnaire. Vitamin D levels were assessed by enzyme immunoassay based on the blood content of its intermediate metabolite 25(OH)D. The determination of biochemical parameters was carried out in the CMD laboratory using the enzyme immunoassay method. Polymorphisms of the VDR, COL1A1, and CALCR genes were analyzed by restriction analysis (PDRF). Results. It was found that patients with CF (38%) are more likely to have low BMD compared with healthy children (18%). Low indicators of nutritional status had anegative impact on the BMD. The processes of osteoresorption prevail over the processes of osteogenesis in CF. The features of the course of the disease neutralize the influence of genetic factors that have been identified in healthy children. The effect of dietary calcium intake was significant for healthy children and had no effect on BMD in patients with CF, since patients adhere to acalcium-enriched diet. The effect of the CALCR and COL1A1 genes and dietary calcium intake on the BMD of healthy children has been established. Conclusion. In cystic fibrosis, the leading risk factors for decreased bone mineral density are: ahistory of meconium ileus, chronic infection with Pseudomonas aeruginosa, low nutritional status, and decreased pulmonary function (FEV1,% predicted). For healthy children, the influence of the CALCR and COL1A1 genes and dietary calcium intake are significant.