[Osteoporosis in children and adolescents].

There is currently no consensus definition of osteopenia and osteoporosis in children according to bone mineral density (BMD) values measured by dual energy x-ray absorptiometry (DXA); interpretation of BMD measures must take into account the child's weight and pubertal status. In children, primary forms of osteoporosis--juvenile idiopathic osteoporosis and osteogenesis imperfecta--are rare; on the other hand, the frequency of secondary osteoporosis is increasing. Fractures, especially of the forearm, are frequent in children. During the peak growth period, bone growth and mineralization are dissociated; in consequence temporary bone fragility promotes fractures. Several recent studies show that children with fractures have reduced BMD and that the occurrence of fractures in children may constitute a risk factor for osteoporosis and fracture during adulthood. In cases of secondary osteoporosis, close monitoring of the causal disease is the key element of treatment; there are very few controlled studies of the prevention or treatment of osteoporosis in children.