Adult Hypophosphatemic Osteomalacia

A 32-year-old lady of Asian descent presented with pain and severe stiffness of the back and hips progressively worsening over several years. She was diabetic but had no past medical history of rickets or renal disease. On examination she was of short stature with marked thoracic kyphosis and flattening of the lumbar spine. Spinal movements were globally restricted and the hips demonstrated a fixed flexion deformity. Her initial diagnosis had been ankylosing spondylitis until she had a MRI scan. Plain radiographs and further MRI of the hips were also performed. Subsequent laboratory tests revealed she was vitamin D deficient, normocalcemic with raised parathyroid hormone (PTH) and alkaline phosphatase.