Ethel S. Siris, MD, is the Madeline C. Stabile Professor of Clinical Medicine in the Department of Medicine, College of Physicians and Surgeons of Columbia University, and the Director of the Toni Stabile Osteoporosis Center of the Columbia University Medical Center, New York-Presbyterian Hospital, all in New York, New York. She is a graduate of Radcliffe College, Harvard University, and received her medical degree from the College of Physicians and Surgeons of Columbia University. An endocrinologist, she works as a clinician, as a clinical investigator and as a medical educator, all in the area of metabolic bone diseases, including osteoporosis and Paget's disease of bone. In her career she has participated in research activities with bisphosphonates, selective estrogen receptor modulators (SERMS) and RANKL inhibitors. Dr.