Children's bone health

textabstractThe thesis can be divided in two main parts. In the first part (Chapter 2 to 5) bone mineral density, bone metabolism and body composition in healthy children and young adults have been evaluated, while in the second part (Chapter 6 to 10) these issues were studied in children with various diseases. Healthy children were studied to gain references for parameters of bone turnover, and to extend our reference data for bone density and body composition. Furthermore, the effect of polymorphisms in two candidate genes, e.g. polymorphisms in the vitamin D receptor gene and the collagen la1 gene, were studied. For a proper interpretation of our findings in diseased children, it is essential to have, preferably own reference data for serum markers of bone turnover, bone density, and body composition. Results of our studies in healthy children are presented in Part I (Chapter 2 to 5). The long-term survival of acute lymphoblastic leukemia (ALL) has improved dramatically during the last decades, consequently more emphasis is being placed on the long- and shortterm side effects of ALL and its treatment. Some of these side-effects, such as osteoporosis, growth retardation and adiposity, have been investigated cross-sectionally in children ten years after diagnosis (Chapter 6). Furthermore, we longitudinally studied children who were newly diagnosed and followed during and after cessation of chemotherapy (Chapter 7). In Chapter 8 and 9 treatment with growth hormone will be discussed. Growth-retarded children with chronic renal failure were treated with growth hormone. The effects of GH treatment on bone density and body composition were compared to children with chronic renal failure but without growth hormone treatment (Chapter 8). Bone density, body composition and serum lipid levels in growth hormone deficient children, and the longitudinal effects of growth hormone treatment on these parameters will be described in Chapter 9. Puberty is considered to be a crucial period for bone mass acquisition. It is therefore important to know whether children with a disorder in pubertal development will achieve an adequate peak bone mass. The effects of gonadotrophin-releasing hormone-agonist (GnRH-a) on bone density and body composition were evaluated in children with precocious or early puberty (Chapter 10). Patients were studied before, during and after cessation of GnRH-a. In Chapter 11 & 12 results will be summarised and discussed, and recommendations for future research are made