It’s just short subway ride from Wall Street to Atlantic Avenue, but for Patricia Kavanagh moving from her office in Manhattan to a new one in Brooklyn meant making a major career change.

From being Ms. Kavanagh, MBA and rising investment banking star at Lehman Brothers, she became Dr. Kavanagh, a prominent neurologist specializing in movement disorders.

“A lot of my friends thought that I was crazy. Even my four children seemed so embarrassed,” Dr. Kavanagh said. “Whatever was I doing going to medical school, where my classmates would be almost half my age?”

And what did her husband think of her walking away from her six-figure salary at Lehman Brothers after getting an MBA from Columbia University?

“Well, he was the one who unconsciously planted the idea in my head,” Dr. Kavanagh said of her spouse, James Grant, founder and editor of Grant’s Interest Rate Observer and an icon of Wall Street. “He’d given me a subscription to the New England Journal of Medicine – almost as a gag. But during my 10 years at Lehman Brothers, I read the journal seriously. I was impressed by how powerfully the case studies were presented, how much intellectual vigor there was in medicine.”

Her epiphany occurred at the office of her children’s pediatrician.

“With four kids, I needed to visit her often,” Dr. Kavanagh said. “As I watched her at work, tending to often unruly children, I would think, ‘How does she do it? What systematic process is at work here?'”

She enrolled at Yeshiva University’s Albert Einstein College of Medicine with the same self-confidence she’d acquired growing up in Dixon, Ill., as one of seven daughters of John and Maria Kavanagh. Encouraged by her father, a manufacturer, and her mother, the 4-year-old Patricia sometimes walked by herself to a nearby grocery to pick up supplies.

“Those trips would give me a sense of enterprise,” she said.

That sense was put to use at Manhattanville College, where she produced a subscription newsletter for students. She expanded its circulation to several colleges around America, and soon she was making $2,000 a year.

After majoring in religion, she applied on a whim to the Baltimore Sun. Much to her astonishment, her very first job was as a fashion editor. That led to a job at the Bergen Record in New Jersey. She met Mr. Grant during this journalistic period, and soon became his spouse and business partner. She then decided she would obtain an MBA and become an investment banker.

All that education and experience turned out to be a prelude to the establishment of a solo medical practice on Atlantic Avenue.

“I developed an understanding of the arithmetic of a small business – which a solo practice is – mostly from working with Jim,” Dr. Kavanagh said. “That was to prove very helpful in my medical practice. The skill of extracting payment from health insurance companies is a work in progress. I am confident that the practice can be profitable – but I doubt that it would be a really lucrative living.”

Then she added: “Patients take note: Your doctor’s financial anxieties are the elephant in the room.”