Teriparatide treatment exerts differential effects on the central and peripheral skeleton: results from the MOAT study

The central and peripheral skeleton was characterised using imaging techniques during 104 weeks of teriparatide treatment. Teriparatide exerts differential effects on the central and the peripheral skeleton. Overall, we did not observe a change in total body bone mineral. Our conclusions are constrained by the study limitations. INTRODUCTION: Teriparatide stimulates bone formation and resorption and therefore can cause bone gain and loss. We simultaneously characterised the central and peripheral skeleton using imaging techniques to better understand the mechanism of action of teriparatide. METHODS: Postmenopausal, osteoporotic women (n = 20, 65.4 ± 5.5 years) were recruited into a 104-week study of teriparatide. Imaging techniques included DXA, quantitative computed tomography (QCT), and high-resolution peripheral quantitative computed tomography (HR-pQCT). RESULTS: Total lumbar spine areal bone mineral content (aBMC) (+ 11.2%), total lumbar spine areal bone mineral density (aBMD) (+ 8.1%), subregional thoracic spine aBMD (+ 7.5%), lumbar spine aBMC (+ 23.5%), lumbar spine aBMD (+ 11.9%), pelvis aBMC (+ 9.3%), and pelvis aBMD (+ 4.3%) increased. However, skull aBMC (- 5.0%), arms aBMC (- 5.1%), legs aBMC (- 2.9%), and legs aBMD (- 2.5%) decreased. Overall, we did not observe a change in total body bone mineral. Increases in L1-L3 volumetric BMD (vBMD) (+ 28.5%) occurred but there was no change in total proximal femur vBMD. Radius and tibia cortical vBMD (- 3.3 and - 3.4%) and tissue mineral density (- 3.2 and - 3.8%) decreased and there was an increase in porosity (+ 21.2 and + 10.3%). Tibia, but not radius, trabecular inhomogeneity (+ 3.2%), and failure load (+ 0.2%) increased, but cortical thickness (- 3.1%), area (- 2.9%), and pore volume (- 1.6%) decreased. CONCLUSIONS: Teriparatide exerts differential effects on the central and the peripheral skeleton. Central trabecular vBMD (L1-L3) is improved, but there is a concomitant decrease in peripheral cortical vBMD and an increase in porosity. Overall, we did not observe a change in total body bone mineral. We acknowledge that our conclusions may be speculative and are constrained by the technical limitations of the imaging techniques used, the lack of a control group, and the small sample size studied.