Bone Abstracts

Background: This case illustrates the longitudinal improvements quantified by serial bone mineral density scans in an adolescent female with juvenile idiopathic osteoporosis treated with pamidronate.

Presenting problem: The girl in question presented at 11 years and 10 months with a 5-month history of increasing back pain. A MRI scan prior to referral had indicated vertebral collapse and osteopenia. She had no medical, social or developmental history of note. There was no family history of bone problems. Her diet was varied with no restrictions. Her exercise had been restricted by the back pain. Her height was 138 cm (<10th centile) for a predicted mid parental height of 160 cm (25th centile) while her weight had increased recently and was 47.3 kg (75–90th centile).

Clinical management: Once all secondary causes of osteoporosis were excluded and a clinical diagnosis of juvenile idiopathic osteoporosis was reached, then i.v. pamidronate treatment was commenced. She received i.v. pamidronate 1 mg/kg for three doses every 3 months for 3 years then 6 monthly for a fourth year. After the first 6 months she became asymptomatic for bone pain and serial DXA scans showed improvement in lumbar spine bone mineral density from 0.381 g/cm² at diagnosis (Z-score −4.3) to a peak of 0.884 g/cm² at cessation of bisphosphonate therapy and this has been maintained at 0.855 g/cm² (Z-score −1.4, 3 years post bisphosphonate therapy). DXA spinal images demonstrate thickening of superior and inferior endplates, reminiscent of a Rugger–Jersey spine. Resolution of pain resulted in an early return to exercise and normalisation of her weight to the 25th centile over the subsequent 3 years.

Discussion: Juvenile osteoporosis is a condition mostly affecting female adolescents that can result in spontaneous resolution. It is a condition of exclusion. Treatment with bisphosphonates has been proposed but the effect can be difficult to quantify in view of the natural improvement of the condition. This case underlines the rapid resolution of symptoms and serial improvements of bone mineral density with pamidronate therapy, but with residual endplate thickening.