Bone Abstracts

Objectives: Differential diagnosis vs. Osteogenesis Imperfecta (OI).

Methods: The parents were Moroccan origin, consanguineous. The patient is an 8 year old girl, who was visited for a first time in our hospital in October 2016, presenting a fracture of the left femur, with dramatic bone deformations, with important disability, unable to walk and with growth retardation (weight 15 kg, length: 92 cm). The first registered fracture is at birth, consisting on a femoral fracture. To differentiate hypophosphatasia (HPP) from OI, the following studies were performed: radiological bone series, MRI, complete bone metabolism biochemical profile including calcium, phosphorus, ALP (alkaline phosphatase), PLP (pyrodoxal-5’-phosphate), PTH (parathyroid hormone), and vitamin D and the genetic molecular analysis for bone dysplasia and OI. The evaluation of the renal impairment included 24 h urine, urine sediment evaluation, renal ultrasound, creatinine and BUN (blood ureic nitrogen).

Results: The radiological bone series and the MRI revealed a severe osteopenia, with long bone deformation, elbows in varum, a wide thorax and xiphoid process in vertebral level with platyspondyly. All these radiological findings are compatible with a bone dysplasia. Renal ultrasound showed nephrocalcinosis. A low bone mineral density with DXA lumbar 0.280 g/cm². Z-Score: −5.8 S.D. The laboratory results included serum calcium in the upper normality range. Vitamin D deficiency and PTH remained normal. The ALP levels were low considering the presence of the fractures. The results of genetic molecular analysis are pending.

Conclusion: In this patient it should be consider the differential diagnosis between HPP and OI. The nephrocalcinosis and low ALP levels with the presence of the fractures led us to possibility of HPP.

Disclosure: The authors declared no competing interests.