LONGITUDINAL-STUDY OF BONE TURNOVER AFTER ACUTE SPINAL-CORD INJURY

Increased bone turnover is a sequel of spinal cord injury (SCI) and pr edisposes to a number of clinically relevant complications, including osteoporosis and fractures. There are limited data available regarding the changes in modern markers of bone metabolism after SCI. We report a g-month longitudinal follow-up of biochemical markers of bone metab olism (free and total deoxypyridinoline, total pyridinoline, N-telopep tide, osteocalcin, and total alkaline phosphatase) and bone mineral de nsitometry in 30 subjects with acute SCI. Markers of bone formation sh owed only a minor rise, remaining within the reference range. In contr ast, markers of bone resorption showed a significant rise after acute SCI, peaking around weeks 10-16, with values up to 10 times the upper limit of normal. Paired bone mineral densities (n = 11; on the average , determined 14 weeks apart) showed no change at the hip, lumbar spine , or radius, but demonstrated a decrement in the entire lower limbs. C hanges in biochemical markers of bone formation and resorption were co mparable in patients with quadriplegia and paraplegia, except for a gr eater increase in quadriplegics in pyridinoline, expressed as a percen tage of baseline. In conclusion, a marked increase in bone resorption and modest changes in bone formation occur after SCI, and possibly inc reased bone resorption occurs in quadriplegia.