BONE-MINERAL DENSITY AND INDEXES OF BONE METABOLISM IN SPINAL-CORD INJURY

We evaluated the pattern of osteoporosis after spinal cord injury, det ermined the time-frame of the changes, and elucidated the relationship among parathyroid hormone levels, biochemical markers of bone formati on, and the pattern of bone mass loss. We included 176 subjects with s pinal cord injury and 62 Subjects without spinal cord injury as contro ls in the study. Bone mineral density of the spine and the proximal fe mur was measured. The participants' age, level of injury, and length o f time since injury were compared with the nonspinal cord-injured cont rols and with each other. Serum levels of calcium, calcitonin, biochem ical markers of bone formation, and parathyroid hormone were determine d. Our results revealed that bone mineral density of the proximal femu r declined and reached fracture threshold at one to five years after i njury. The decline was detected at 12 months after injury in all age g roups. Spinal bone mineral density neither declined significantly nor reached fracture threshold. Parathyroid hormone levels declined before the end of the first year postinjury and increased at one to nine yea rs postinjury in the 20- to 39-year age group. The increase correlated with the initial decline of bone mineral density of the proximal femu r. Our studies in spinal cord-injured subjects revealed a pattern of o steoporosis similar to age and parathyroid dysfunction-related osteopo rosis. No other correlation was detected between indexes of bone metab olism and bone mineral density measurements.