ST. LOUIS — Inside the more than 600 Catholic hospitals across the country, not a single nun can be found occupying a chief executive suite, according to the Catholic Health Association. Nuns founded and led those hospitals in a mission to treat sick and poor people, but some were also shrewd business leaders.

Sister Irene Kraus, a former chief executive of Daughters of Charity National Health System, was famous for coining the phrase “no margin, no mission.” It means hospitals must succeed — generating enough revenue to exceed expenses — to fulfill their original mission. The Catholic Church still governs the care that can be delivered to millions in those hospitals each year, using religious directives to ban abortions and limit contraceptives, in vitro fertilization, and medical aid in dying.

But over time, that focus on margins led the hospitals to transform into behemoths that operate for-profit subsidiaries and pay their executives millions, according to hospital tax filings. These institutions, some of which are for-profit companies, now look more like other megacorporations than like the charities for the destitute of yesteryear. The absence of nuns in the top roles raises the question, said M.

Therese Lysaught, a Catholic moral theologist and professor at Loyola University Chicago: “What does it mean to be a Catholic hospital when the enterprise has been so deeply commodified?” The St. Louis area serves as the de facto capital of Catholic hospital syste.