Dr. Michael T. Collins is a physician-scientist whose career has focused on elucidating the endocrine regulation of calcium and phosphate homeostasis and translating these discoveries into novel therapies for rare skeletal and endocrine disorders. His work included the first clinical use of both calcium-sensing receptor agonists (calcimimetics) and antagonists (calcilytics) to treat human disease, establishing receptor-targeted approaches for disorders of calcium homeostasis. His laboratory made fundamental contributions to the biology of fibroblast growth factor 23 (FGF23), helping establish bone as an endocrine organ that regulates systemic phosphate homeostasis, defining mechanisms of FGF23 excess and deficiency, and pioneering mechanism-based therapies for phosphate disorders. He also helped define the reciprocal interactions between parathyroid hormone and FGF23 in the regulation of mineral metabolism, providing a physiologic framework for understanding disorders of calcium and phosphate homeostasis. Throughout his career, Dr. Collins has combined fundamental physiologic investigation with translational research, using rare diseases to uncover biological mechanisms that have led directly to first-in-disease studies and targeted therapies. Collectively, his research demonstrates how investigation of rare endocrine disorders can reveal fundamental principles of human physiology while accelerating the development of transformative therapies that have changed clinical practice.