S R Cummings1, R Eastell2. 1. S.F. Coordinating Center, California Pacific Medical Center Research Institute, University of California, Mission Hall: Box #0560, 550-16th Street, 2nd Floor, San Francisco, CA, 94143, USA. steven.cummings@ucsf.edu. 2. Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK.