John T. Potts Jr. shaped modern calcium biology and the culture of academic endocrinology
John T. Potts Jr., MD, DSc, died on August 12, 2026, at age 94, leaving behind a body of work that helped define how endocrinologists understand calcium homeostasis, parathyroid hormone biology, and the clinical diagnosis of hyperparathyroidism. He also left a different kind of legacy: an institution-building style that trained scientists, strengthened departments, and altered the culture of academic medicine at Massachusetts General Hospital and Harvard Medical School.
His career moved with uncommon continuity from bedside observation to molecular endocrinology. The same clinical problem that first drew his attention as a medical student — hyperparathyroidism — remained central to his scientific life for decades.
From a medical student’s patient to a lifetime of endocrine discovery
Potts grew up in Moorestown, N.J., in a family of florists. He entered La Salle College interested in English literature before deciding on medicine, then encountered a patient with hyperparathyroidism during clinical rotations at the University of Pennsylvania School of Medicine. That experience pushed him toward the mechanism of disease rather than the label alone. After graduating in 1957 and joining the Massachusetts General Hospital for internship and residency, he trained in a department still strongly influenced by Fuller Albright’s model of extracting physiology from careful clinical observation.
He then went to the National Institutes of Health to learn science at a deeper level. There, working with Christian Anfinsen, he learned protein chemistry and later joined Gerald Aurbach in efforts to purify and characterize parathyroid hormone.
A giant step followed from chemistry to physiology. With collaborators, Potts and Aurbach determined the amino acid sequence of PTH and, with Berson and Yalow, developed a radioimmunoassay for the hormone. Those experiments showed that falling serum calcium stimulates PTH secretion and rising calcium suppresses it, establishing PTH as the central mediator of calcium homeostasis. In practical clinical terms, this transformed a confusing metabolic disorder into a measurable endocrine pathway.
Assays, receptors, and the clinical diagnosis of hyperparathyroidism
Potts returned to MGH in 1968 as chief of the Endocrine Unit and built a group that repeatedly adapted the next major technology rather than waiting for it to arrive. He sent young physician-scientists to laboratories at Harvard and MIT, where they learned recombinant DNA and molecular biology. Those collaborations helped enable cloning of PTH and later the PTH/PTHrP receptor.
The work did not stop at basic discovery. With Gino Segre and others, he developed more sensitive and specific immunoradiometric assays for PTH, improving the diagnosis of primary hyperparathyroidism and helping distinguish it from humoral hypercalcemia of malignancy. In endocrine practice, that distinction can alter the entire diagnostic path: whether a patient is being evaluated for glandular overproduction, an occult malignancy, or a broader calcium disorder.
He also helped shape consensus guidance for the management of hyperparathyroidism and laid mechanistic groundwork for PTH-based treatment of osteoporosis. His career linked molecular insight to bedside decision-making without forcing one side of medicine to eclipse the other.
Leadership built on distributed governance and deliberate mentorship
In 1981, Potts became chair of medicine and physician-in-chief at MGH, positions he held until 1996. He protected time for his own research group throughout that period while also broadening the hospital’s research enterprise. He helped bring molecular biology to MGH and supported the development of MGH East in Charlestown, which enabled the growth of the MGH Cancer Center, the Cardiovascular Research Institute, and other major programs. He later served as director of research from 1996 to 2004.
Potts described his leadership approach as distributed governance: recruit excellent people, give them room to build, and create a culture in which colleagues celebrate one another’s success rather than view it as a threat. “If you celebrate young people around you,” he observed, “they feel like they can grow.”
He acted on that belief. He was an early advocate for recruiting and advancing physicians from groups underrepresented in medicine, formed a Minority Recruitment Committee in the department, and supported the Biomedical Science Careers Program. He also created the MGH Society of Research Fellows, which helped young physician-scientists navigate the uncertain early years of academic careers. Many of those trainees later moved into influential roles in medicine and industry.
One sentence captures the kind of mentor he became: he listened closely enough to hear what a younger colleague wanted, not what he himself would have chosen.
A mentor whose influence extended far beyond the laboratory
His mentorship was personal and unusually durable. He remembered the details of colleagues’ science, their career ambitions, and their families. When illness or tragedy struck, he used his broad network to connect people with specialists and then followed their progress. In one striking example, he called a colleague nearly every evening for a year to check on them.
He served as president of the Endocrine Society in 1987–1988, at a time when its clinical and basic-science communities might have drifted apart. He helped preserve their shared intellectual home. The society recognized him with both the Ernst Oppenheimer Award and its highest honor, the Fred Conrad Koch Award. His honors also included the 2013 George M. Kober Medal of the Association of American Physicians and election to the National Academy of Sciences, the National Academy of Medicine, and the American Academy of Arts and Sciences.
A personal life that anchored an academic career
Potts’s professional life was matched by a wide-ranging personal one. He and his wife, Susanne, shared interests in art, architecture, music, tennis, philosophy, and social causes, along with a love of entertaining. Their first date involved a concert that collided with an important NIH lecture; after some negotiation, she joined him at the lecture instead. The lecture was dull, by their own account, but the relationship flourished.
Their home became a gathering place for trainees, faculty, and friends. Small dinners grew into larger holiday parties where generations of physicians could talk about medicine, science, politics, and life. Susanne’s steady support helped sustain a household that welcomed the demands of academic medicine. Potts was a devoted father to John, Martha, and Stephan and a proud grandfather.
Endocrinology lost a pioneer, MGH lost one of its great institutional stewards, and academic medicine lost a mentor whose influence still lives in the people he trained. He began his clinical journey at MGH, returned there as a leader, and received care there at the end of his life. The scientific questions he pursued, the people he recruited, and the culture he built remain embedded in modern endocrine medicine.