CHICAGO – A nurse may soon be your doctor.

With a looming shortage of primary care doctors, 28 states are considering expanding the authority of nurse practitioners.

These nurses with advanced degrees want the right to practice without a doctor’s watchful eye and to prescribe narcotics. And if they hold a doctorate, they want to be called “Doctor.”

For years, nurse practitioners have been playing a bigger role in the nation’s health care, especially in regions with few doctors. With 32 million more Americans gaining health insurance within a few years, the health care overhaul is putting more money into nurse-managed clinics.

The medical establishment is fighting to protect turf. In some statehouses, doctors have shown up in white coats to testify against nurse practitioner bills. The American Medical Association, which supported the national health care overhaul, says a doctor shortage is no reason to put nurses in charge and endanger patients.

Nurse practitioners argue there’s no danger. They say they’re highly trained and as skilled as doctors at diagnosing illness during office visits. They know when to refer the sickest patients to doctor specialists. Plus, they spend more time with patients and charge less.

“We’re constantly having to prove ourselves,” said Chicago nurse practitioner Amanda Cockrell, 32, who tells patients she’s just like a doctor “except for the pay.”

On top of four years in nursing school, Cockrell spent another three years in a nurse practitioner program, much of it working with patients. Doctors generally spend four years in undergraduate school, four years in medical school and an additional three in primary care residency training.

Medicare, which sets the pace for payments by private insurance, pays nurse practitioners 85 percent of what it pays doctors. An office visit for a Medicare patient in Chicago, for example, pays a doctor about $70 and a nurse practitioner about $60.

The health care overhaul law gave nurse midwives, a type of advanced practice nurse, a Medicare raise to 100 percent of what obstetrician-gynecologists make — and that may be just the beginning.

States regulate nurse practitioners and laws vary on what they are permitted to do:

n In Florida and Alabama, for instance, nurse practitioners are barred from prescribing controlled substances.

n In Washington, nurse practitioners can recommend medical marijuana to their patients when a new law takes effect in June.

n In Montana, nurse practitioners don’t need a doctor involved with their practice in any way.

n Many other states put doctors in charge of nurse practitioners or require agreements signed by a doctor.

n In some states, nurse practitioners with a doctorate in nursing practice can’t use the title “Dr.” Most states allow it.

The AMA argues the title “Dr.” creates confusion. Nurse practitioners say patients aren’t confused by veterinarians calling themselves “Dr.” Or chiropractors. Or dentists.

“I don’t think patients are ever confused. People are not stupid,” said Linda Roemer, a nurse practitioner in Sedona, Ariz., who uses “Dr. Roemer” as part of her e-mail address.

What’s the evidence on the quality of care given by nurse practitioners?

The best U.S. study comparing nurse practitioners and doctors randomly assigned more than 1,300 patients to either a nurse practitioner or a doctor. After six months, overall health, diabetes tests, asthma tests and use of medical services like specialists were essentially the same in the two groups.

“The argument that patients’ health is put in jeopardy by nurse practitioners? There’s no evidence to support that,” said Jack Needleman, a health policy expert at the University of California Los Angeles School of Public Health.

Other studies have shown that nurse practitioners are better at listening to patients, Needleman said. And they make good decisions about when to refer patients to doctors for more specialized care.