Peripheral quantitative computed tomography is useful to monitor response to alendronate therapy in postmenopausal women.

A forearm fracture (Colles' fracture) is often the first sign of osteoporosis and may suggest underlying skeletal fragility. Therefore, establishment of a more accurate and reliable method for the measurement of bone mineral density (BMD) at the distal radius would be beneficial for patients who suffer from osteoporosis. The objective of this study was to evaluate the usefulness of peripheral quantitative computed tomography (pQCT) to monitor the response to alendronate therapy at the distal radius in early postmenopausal Japanese women. Thirty-two early postmenopausal women who were diagnosed with osteoporosis or osteopenia were randomized to either alendronate or control treatment. We analyzed the BMD of the distal radius by pQCT, lumbar spine by dual-energy X-ray absorptiometry (DXA) and the biochemical markers of bone turnover (deoxypyridinoline) at baseline, 3, 6 and 12 months. The control group showed a significant decrease from baseline in the trabecular BMD of the radius at 12 months (3.5 +/- 3.7%; p < 0.01), whereas the alendronate group showed a significant increase (4.3 +/- 8.1%). The changes in the trabecular BMD of the radius between the alendronate and control groups were statistically different at 6 and 12 months (p < 0.01). However, in the total BMD at the diaphysis of the radius, no significant differences were seen in the changes in bone densities between the alendronate and control groups after 1 year of treatment. pQCT detected significant differences in BMD of the radius in early postmenopausal women after 1 year of treatment with alendronate. Collectively, our preliminary clinical trial showed that pQCT might be useful to monitor response to alendronate therapy, especially at the radius, and it might explain why alendronate prevents Colles' fracture.