Oncogenic osteomalacia: clinical presentation, densitometric findings, and response to therapy

A 72-yr-old white female who had previously enjoyed excellent health presented with global bone and muscle pain, and chronic fatigue. Her evaluation revealed an increased sedimentation rate and mild anemia, and a diagnosis of polymyalgia rheumatica was made. Prednisone therapy was of little benefit. A laboratory evaluation revealed mild hypocalcemia, marked hypophosphatemia, elevated alkaline phosphatase, normal 25- hydroxyvitamin D, and undectable 1,25-dihydroxyvitamin D. A diagnosis of oncogenic osteomalacia was made and the patient received calcitriol and neutraphos therapy. The patient's initial bone density by dual energy X-ray absorptiometry of the lumbar spine was 0.847 g/cm2 (T score -1.96) and of the femoral neck was 0.669 gm/cm2 (T score -2.89). After 40 mo of treatment with calcitriol and neutraphos, the bone mineral density of the lumbar spine and hip rose dramatically by 47.8 and 59.1%, respectively. Although oncogenic osteomalacia is a very rare metabolic bone disease, its recognition and appropriate treatment can have a dramatic effect not only on the bone mineral density of the patient, but also on the patient's general health and feeling of well-being.