The deeper battle is over who gets to treat patients first. Pharmacists, physical therapists and nurses largely play secondary roles to physicians, since patients tend to go to them only after a prescription, a referral or instructions from a physician. By requiring doctorates of new entrants, leaders of the pharmacy and physical therapy professions hope their members will be able to treat patients directly and thereby get a larger share of money spent on patient care.

As demand for health care services has grown, physicians have stopped serving as the sole gatekeepers for their patients’ entry into the system. So physicians must increasingly share their patients — not only with one another but also with other professions. Teamwork is the new mantra of medicine, and nurse practitioners and physician assistants (sometimes known as midlevels or physician extenders) have become increasingly important care providers, particularly in rural areas.

But while all physician organizations support the idea of teamwork, not all physicians are willing to surrender the traditional understanding that they should be the ones to lead the team. Their training is so extensive, physicians argue, that they alone should diagnose illnesses. Nurses respond that they are perfectly capable of recognizing a vast majority of patient problems, and they have the studies to prove it. The battle over the title “doctor” is in many ways a proxy for this larger struggle.

For patients, the struggle has brought an increasing array of professionals trained to deal with their day-to-day health woes, but also at times confusion over who is responsible for their care and what sort of training they have.

Six to eight years of collegiate and graduate education generally earn pharmacists, physical therapists and nurses the right to call themselves “doctors,” compared with nearly twice that many years of training for most physicians. For decades, a bachelor’s degree was all that was required to become a pharmacist. That changed in 2004 when a doctorate replaced the bachelor’s degree as the minimum needed to practice. Physical therapists once needed only bachelor’s degrees, too, but the profession will require doctorates of all students by 2015 — the same year that nursing leaders intend to require doctorates of all those becoming nurse practitioners.

Dr. Kathleen Potempa, dean of the University of Michigan School of Nursing and the president of the American Association of Colleges of Nursing, said that the profession’s new doctoral degree, called the doctor of nursing practice, was simply about remaining current. “Knowledge is exploding, and the doctor of nursing practice degree evolved out of a grass-roots recognition that we need to continuously improve our curriculum,” she said.

Last year, 153 nursing schools gave doctor of nursing practice degrees to 7,037 nurses, compared with four schools that gave the degrees to 170 nurses in 2004, when the association of nursing schools voted to embrace the new degree. In 2008, there were 375,794 nurses with master’s degrees and 28,369 with doctorates, according to a recent government survey.