[Uncommon form of idiopathic osteoporosis with hypercalciuria, growth retardation and mental retardation].

Case report of a 18 year old boy with short stature, microceophaly, mental retardation and multiple dysmorphic signs. At the age of 9 years a severe generalised osteoporosis was discovered. A pathological fracture of the greenwoor type healed without proper callus formation. The osteoporosis persists without signs of either deterioration or improvement. The serum phosphorus is slightly decreased, while serum calcium, alkaline phosphatase and renal functions are normal. The main biochemical finding is a constant hyperclaciuria of 6-13 mg/kg/24 h, which can be corrected by treatment with oral sodium phosphate. No other chronic disease could be found which would explain the bone disease. The complex disease of this boy does not fit into the known pictures of osteogenesis imperfecta, idiopathic juvenile osteoporosis or of idiopathic hypercalciuria, and might therefore be another type of demineralising bone disease. It is suggested, that the cause might be an impairment of the calcium fixation of collagen fibres during desmal ossification.