Robert P Heaney Dr. Robert P. Heaney's six decades of research investigating bone physiology and biology had a profound impact in the field of osteoporosis. His early work at Creighton included the Creighton University “Nun” Study. Many people in the field recognize this study when it is mentioned. This project was originally designed as a 20-year project. Roman Catholic nuns with mother houses in the Omaha, NE, USA, area were invited to attend an 8-day inpatient metabolic balance study at 5-year intervals. Each admission was preceded by a 7-day diary recording all dietary intakes. The daily food provided to each inpatient study participant was matched for calcium, phosphorus, protein, fat, and carbohydrate to the intake recorded in the diaries. Dr. Heaney characterized plasma calcium kinetics using radio-calcium isotopes, which described the interface between the calcium in the skeleton and that in the circulation. He also measured calcium absorption efficiency and recorded obligate losses of calcium in the urine and stool. All of this focused on calcium and skeletal physiology, and pathogenesis of osteoporosis. This project ultimately culminated after 41 years with each subject studied at 5-year intervals. The study sample of 161 nuns who entered the study in 1967 decreased to 131 at the end of the study, ie, only 30 dropouts over this 41-year study, some of whom were deceased. This study documented the importance of calcium nutrition and the calcium loss at the time of menopause, and set the standard for the US recommendations for calcium intake. Dr. Heaney's research contributions pertained not only to bone and osteoporosis but also to other illnesses, such as end-stage renal disease and insulin resistance, in the study of vitamin D. He applied his skills in biologic kinetics to characterize the appearance and disappearance of calciferol and its various metabolites in the serum of humans. His research in vitamin D nutrition and its physiology has had an enormous impact on the understanding of vitamin D physiology. Dr. Heaney always stressed that a research project is not complete until the findings are disseminated. He took that responsibility seriously and was a prolific writer and a frequent speaker at scientific, corporate, and community meetings. He authored 866 scientific articles including abstracts, reviews and other scientific papers. He participated actively in policy making in groups such as the Office of Technology Assessment, US Congress, Scientific Advisory Panel on Osteoporosis and the Panel on Calcium and Related Nutrients, Food & Nutrition Board, National Academy of Science (NAS). His achievements were widely recognized and his awards include the Creighton University Lifetime Achievement Research Award, the Frederick C Bartter Award from the American Society for Bone and Mineral Research, the Kappa Delta award from the American College of Orthopedic Surgeons, the E.V. McCollum Award of the American Society for Clinical Nutrition, and the Institute CANDIA Scientific Prize from France. He was recognized by the National Osteoporosis Foundation as a “Legend of Osteoporosis.” Perhaps most importantly, he focused widespread attention on the importance of osteoporosis. In recognition of this, he was presented a lifetime achievement award in the US House of Representatives on November 10, 2015. Dr. Heaney has mentored a large number of people including the authors of this memorial. He was an icon in the fields of osteoporosis, bone physiology, bone diseases in general, and vitamin D. His mentorship has been inspirational for our students, residents, and fellows at Creighton University as well as similar trainees in other institutions. He has been an enthusiastic, passionate teacher of medicine and bone pathology and physiology. Dr. Heaney had another dimension known mostly inside Creighton. He has been very active in Creighton University's spiritual community. He was well known for his passion for the scripture and his contributions to “Daily Reflections” on the Creighton website. His spiritual writings have been a source of great inspiration for persons at Creighton University and beyond. He also wrote for a monthly Catholic magazine America and for the Creighton Magazine. Dr. Heaney and his late wife, Barbara, raised seven children, and, at his death, his descendants include 14 grandchildren, and three great grandchildren. They all were a source of great pride and much enjoyment for him. Dr. Heaney will be remembered as a healer, a thinker, and a man of grace and generosity. We are all greatly saddened by his loss. Robert R Recker, MD Osteoporosis Research Center, Creighton University, Omaha, NE, USA Joan M Lappe, PhD Osteoporosis Research Center, Creighton University, Omaha, NE, USA