A 48-year-old patient presented with severe and progressive painful shrinkage of the thoracic cage as the result of repetitive minor fractures. Chest radiographs showed a severe form of flail chest, and the lateral spine was overwhelmed by severe rigid scoliosis.
At the age of 35 years and because of repetitive episodes of vertebral fractures and low bone mass, the diagnosis of idiopathic osteoporosis was established. The patient was treated with 20 μg teriparatide (subcutaneous injection of parathyroid hormone 1-34) and 0.5 μg calcitriol per day for 18 months to improve his osteoporotic status.
In addition, he received supplemental calcium and vitamin D. His bone mineral density in L1-L4 improved and increased to 0.927 g/cm2 corresponding to a T-score of −2.1 and in the femoral neck to 0.833 g/cm2 corresponding to a T-score of −1.4. Unfortunately, this treatment protocol converted his backbone into a more rigid spine, resulting in a collapse of the thoracic cage.
Family pedigree search was the baseline tool to reject the diagnosis of idiopathic osteoporosis. The clinical and radiographic phenotypes of the patient’s 2 daughters were the key element to refute the diagnosis of idiopathic osteoporosis. Osteogenesis imperfecta was identified.
Assessment
At the age of 30 years, the patient progressively reported back pain. Radiographs and magnetic resonance imaging were performed. He had vertebral fractures of T 6, 7, 9, 12, and L2 amid rigid scoliosis.
The dual-energy X-Ray absorptiometry scan showed a low bone mineral density of 0.661 g/cm2 in L1-L4 corresponding to a T-score of −4.3 and a low bone mineral density of 0.705 g/cm2 in the femoral neck corresponding to a T-score of −2.5. He showed normal serum calcium and a low serum phosphate of 0.71 mmol/L (normal, 0.83-1.48 mmol/L). Serum CrossLaps (2.9 nM; normal, 0.00-7.78 nM) and parathyroid hormone parameters (8.73 pg/mL; normal, 8.3-68.0) were within the normal range.
Serum 25-hydroxy vitamin D was estimated by radioimmunoassay to be 36 ng/mL (desirable 25(OH)D levels are 36-48 ng/mL). At this stage, the diagnosis of idiopathic osteoporosis was established. Therefore, 20 μg teriparatide (subcutaneous injections) 1-34 and 0.5 μg calcitriol per day were prescribed for 18 months. Bone mineral density in L1-L4 increased to 0.927 g/cm2 corresponding to a T-score of −2.1 and in the femoral neck increased up to 0.833 g/cm2 corresponding to a T-score of −1.4.
In response to this treatment, there was a dramatic improvement in his bone mineral density. Nevertheless, the spine rigidity became more profound, and over time the ribs were rendered too fragile. Idiopathic osteoporosis was the adopted diagnosis for more than a decade, until we decided to examine the rest of the family subjects. The key element in establishing the diagnosis of osteogenesis imperfecta was the clinical and radiographic examination of the 2 daughters.
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-Ali Al Kaissi, MD, MS, Farid Ben Chehida, MD, Franz Grill, MD, Rudolf Ganger, MD, PhD
This article originally appeared in the June 2016 issue of The American Journal of Medicine.
