RT Journal A1 SMITH R T1 IDiopathic juvenile osteoporosis JF American Journal of Diseases of Children JO American Journal of Diseases of Children YR 1979 FD September 1 VO 133 IS 9 SP 889 OP 891 DO 10.1001/archpedi.1979.02130090017001 UL http://dx.doi.org/10.1001/archpedi.1979.02130090017001 AB Osteoporosis in childhood is rare and has few known causes. These include Cushing's syndrome, osteogenesis imperfecta (OI), homocystinuria, Turner's syndrome, malabsorption, and immobilization. When such causes have been excluded, some patients remain in whom the cause of the osteoporosis is obscure. The most severe form of this disorder was defined by the late Charles Dent and his colleagues1-4 under the title of idiopathic juvenile osteoporosis (IJO), although previous descriptions did exist. The cardinal features are onset just before puberty; fractures of the vertebrae and the long bones, particularly the metaphyses, that lead to back pain, deformity, and difficulty in walking; the formation of new but osteoporotic bone; and spontaneous recovery (see p 894). The skeleton previously appears to be normal. Calcium balance may be negative in the early phase. Related conditions occur that differ only in their time of onset or in severity. Thus, Kooh and his co-workers5