The Treatment of Osteoporosis: Antiresorptive Therapy

Femur ultrasound (FemUS)--first clinical results on hip fracture discrimination and estimation of femoral BMD

SUMMARY

A quantitative ultrasound (QUS) device for measurements at the proximal femur was developed and tested in vivo (Femur Ultrasound Scanner, FemUS). Hip fracture discrimination was as good as for DXA, and a high correlation with hip BMD was achieved. Our results show promise for enhanced QUS-based assessment of osteoporosis.

INTRODUCTION

Dual X-ray absorptiometry (DXA) at the femur is the best predictor of hip fractures, better than DXA measurements at other sites. Calcaneal quantitative ultrasound (QUS) can be used to estimate the general osteoporotic fracture risk, but no femoral QUS measurement has been introduced yet. We developed a QUS scanner for measurements at the femur (Femur Ultrasound Scanner, FemUS) and tested its in vivo performance.

METHODS

Using the FemUS device, we obtained femoral QUS and DXA on 32 women with recent hip fractures and 30 controls. Fracture discrimination and the correlation with femur bone mineral density (BMD) were assessed.

RESULTS

Hip fracture discrimination using the FemUS device was at least as good as with hip DXA and calcaneal QUS. Significant correlations with total hip bone mineral density were found with a correlation coefficient R (2) up to 0.72 and a residual error of about one half of a T-score in BMD.

CONCLUSIONS

QUS measurements at the proximal femur are feasible and show a good performance for hip fracture discrimination. Given the promising results, this laboratory prototype should be reengineered to a clinical applicable instrument. Our results show promise for further enhancement of QUS-based assessment of osteoporosis.

Bone density and markers of bone turnover in predicting fracture risk and how changes in these measures predict fracture risk reduction

Surrogate markers in clinical medicine provide a useful means to assess therapeutic response to pharmacologic therapy in a wide range of chronic disease states. In the area of osteoporosis, the surrogate markers of change in bone mineral density (BMD) and bone turnover markers (BTM) provide the clinician with a means of assessing the biologic response to osteoporosis-specific pharmacologic agents. Increases in BMD and/or reductions in BTM can independently be correlated to reductions in vertebral and nonvertebral fracture risk. In managing osteoporosis patients, the BTM change at an earlier point of time after initiation of therapy and a change in BTM can provide earlier feed-back to the patient and clinician regarding issues such as compliance and a bone biologic response. An increase in BMD at 12 or 24 months after initiation of therapy is also evidence of an improvement in bone strength though with antiresorptive agents no change in BMD may also be associated with risk reduction within clinical trial sets. In this regard, changes in BMD and BTM are complimentary in their application to patient management.

The effect of calcitonin and growth hormone on urinary deoxypyridinoline levels in burned patients

Reduced bone formation and bone loss have been documented in patients following burn injury. Urinary deoxypyridinoline (DPD) is accepted as a marker of collagen breakdown activity. Because calcitonin (CT) diminishes bone resorption and growth hormone (GH) increases bone formation and density in GH-deficient patients, we studied the short-term effects of CT and GH on urinary DPD levels in burned patients. In 30 patients with severe burns, urinary DPD levels were investigated for 3 days following hospitalisation. Then the patients were divided into 3 groups of 10. In the CT group, CT 100U was injected subcutaneously daily for 5 days. In the GH group, GH 0.1mg/kg was injected subcutaneously three times in a week. In the control group, isotonic saline solution 0.1mg/kg was injected subcutaneously three times in a week. In all groups, following the last dose of the agents, urinary DPD levels were investigated for 3 days again. Mean burn size and age were not significantly different between the groups. Urinary DPD level obtained in the early period was 16.5 +/- 3.1nM in the CT group, 10.4 +/- 5.3nM in the GH group and 18.6 +/- 2.7nM in the control group. There were no statistical differences among the groups (P > 0.5, for all). Urinary DPD level obtained in the late period was 4.5 +/- 1.0nM in the CT group, 14.4 +/- 5.9nM in the GH group and 36.6 +/- 2.1nM in the control group. The differences between the CT group and control group, the CT group and GH group and the GH group and control group were statistically significant (P < 0.001, P < 0.01, P < 0.01, respectively). In the comparison of early and late urinary DPD levels, a significant decrease was only obtained in the CT group (P < 0.001, Z:6.5). In the other 2 groups, DPD levels increased in the late period. We concluded that GH is not effective in decreasing urinary DPD levels. On the contrary, CT was found to very effective in decreasing urinary DPD levels. This decrease in urinary DPD levels may be associated with diminished bone loss