Bone markers and bone mineral density during growth hormone treatment in children with growth hormone deficiency

Growth hormone (GH) has a positive impact on muscle mass, growth and bone f ormation. It is known to interact with the bone-forming unit, with well-doc umented increases in markers of bone formation and bone resorption within w eeks of the start of GH therapy. These changes relate significantly to shor t-term growth rate, but it is not evident that they predict long-term respo nse to GH therapy. The consequences of GH deficiency (GHD) and GH replaceme nt therapy on bone mineral density (BMD) have been difficult to interpret i n children because of the dependency of areal BMD on height and weight. Som e studies have tried to overcome this problem by calculating volumetric BMD , but results are conflicting. The attainment of a normal peak bone mass in an individual is considered important for the future prevention of osteopo rosis. From the limited data available, it appears difficult to normalize b one mass totally in GH-deficient individuals, despite GH treatment for long periods. Studies to date examining the interaction between GH and bone hav e included only small numbers of individuals, making it difficult to interp ret the study findings. It is hoped that these issues can be clarified in f uture research by the direct measurement of bone density (using quantitativ e computer tomography), Mineralization is only one facet of bone strength, however; other important components (e.g. bone structure and geometry) shou ld be addressed in future paediatric studies. Future studies could also add ress the importance of the degree of GHD in childhood; how GH dose and insu lin-like growth factor-1 levels achieved during therapy relate to the final outcome; whether or not the continuation of GH therapy after the attainmen t of final height may further enhance bone mass; whether the timing and dos e of other treatments (e.g. sex hormone replacement therapy) are critical t o the outcome; and whether GHD in childhood is associated with an increased risk of fracture. Copyright (C) 2000 S. Karger AG. Basel.