Differing effects of PTH 1–34, PTH 1–84, and zoledronic acid on bone microarchitecture and estimated strength in postmenopausal women with osteoporosis: An 18-month open-labeled observational study using HR-pQCT

Authors

  • Stinus Hansen,

    Corresponding author
    1. Department of Endocrinology, Odense University Hospital, Odense, Denmark
    2. Institute of Clinical Research, University of Southern Denmark, Odense, Denmark
    • Department of Endocrinology, Institute of Clinical Research, Odense University Hospital, University of Southern Denmark, Kloevervaenget 6.1.sal, DK-5000 Odense C, Denmark.
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  • Ellen M Hauge,

    1. Department of Rheumatology, Aarhus University Hospital, Aarhus, Denmark
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  • Jens-Erik Beck Jensen,

    1. Osteoporosis Research Clinic, Hvidovre University Hospital, Hvidovre, Denmark
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  • Kim Brixen

    1. Department of Endocrinology, Odense University Hospital, Odense, Denmark
    2. Institute of Clinical Research, University of Southern Denmark, Odense, Denmark
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Abstract

Whereas the beneficial effects of intermittent treatment with parathyroid hormone (PTH) (intact PTH 1–84 or fragment PTH 1–34, teriparatide) on vertebral strength is well documented, treatment may not be equally effective in the peripheral skeleton. We used high-resolution peripheral quantitative computed tomography (HR-pQCT) to detail effects on compartmental geometry, density, and microarchitecture as well as finite element (FE) estimated integral strength at the distal radius and tibia in postmenopausal osteoporotic women treated with PTH 1–34 (20 µg sc daily, n = 18) or PTH 1–84 (100 µg sc daily, n = 20) for 18 months in an open-label, nonrandomized study. A group of postmenopausal osteoporotic women receiving zoledronic acid (5 mg infusion once yearly, n = 33) was also included. Anabolic therapy increased cortical porosity in radius (PTH 1–34 32 ± 37%, PTH 1–84 39 ± 32%, both p < 0.001) and tibia (PTH 1–34 13 ± 27%, PTH 1–84 15 ± 22%, both p < 0.001) with corresponding declines in cortical density. With PTH 1–34, increases in cortical thickness in radius (2.0 ± 3.8%, p < 0.05) and tibia (3.8 ± 10.4%, p < 0.01) were found. Trabecular number increased in tibia with both PTH 1–34 (4.2 ± 7.1%, p < 0.05) and PTH 1–84 (5.3 ± 8.3%, p < 0.01). Zoledronic acid did not impact cortical porosity at either site but increased cortical thickness (3.0 ± 3.5%, p < 0.01), total (2.7 ± 2.5%, p < 0.001) and cortical density (1.5 ± 2.0%, p < 0.01) in tibia as well as trabecular volume fraction in radius (2.5 ± 5.1%, p < 0.05) and tibia (2.2 ± 2.2%, p < 0.01). FE estimated bone strength was preserved, but not increased, with PTH 1–34 and zoledronic acid at both sites, whereas it decreased with PTH 1–84 in radius (−2.8 ± 5.8%, p < 0.05) and tibia (–3.9 ± 4.8%, p < 0.001). Conclusively, divergent treatment-specific effects in cortical and trabecular bone were observed with anabolic and zoledronic acid therapy. The finding of decreased estimated strength with PTH 1–84 treatment was surprising and warrants confirmation. © 2013 American Society for Bone and Mineral Research.

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