Chicago ? An influential government-appointed medical panel is urging doctors to routinely screen all American teens for depression — a bold step that acknowledges that nearly 2 million teens are affected by this debilitating condition.

Most are undiagnosed and untreated, said the panel, the U.S. Preventive Services Task Force, which sets guidelines for doctors on a host of health issues.

The task force recommendations appear in April’s issue of the journal Pediatrics. And they go farther than the American Academy of Pediatrics’ own guidance for teen depression screening.

An estimated 6 percent of U.S. teenagers are clinically depressed. Evidence shows that detailed but simple questionnaires can accurately diagnose depression in primary-care settings such as a pediatrician’s office.

The task force said that when followed by treatment, including psychotherapy, screening can help improve symptoms and help kids cope. Because depression can lead to persistent sadness, social isolation, school problems and even suicide, screening to treat it early is crucial, the panel said.

The task force is an independent panel of experts convened by the federal government to establish guidelines for treatment in primary-care. Its new guidance goes beyond the pediatrics academy, which advises pediatricians to ask teen patients questions about depression. Other doctor groups advise screening only high-risk youngsters.

Because depression is so common, “you will miss a lot if you only screen high-risk groups,” said Dr. Ned Calonge, task force chair and chief medical officer for Colorado’s Department of Public Health and Environment.

The group recommends research-tested screening tests even for kids without symptoms. It cited two questionnaires that focus on depression tip-offs, such as mood, anxiety, appetite and substance abuse.

Calonge stressed that the panel does not want its advice to lead to drug treatment alone, particularly antidepressants that have been linked with increased risks for suicidal thoughts. Routine testing should only occur if psychotherapy is also readily available, the panel said. Calonge said annual screening likely would be enough.

While primary care doctors have full plates just dealing with physical ailments, many recognize the importance of providing mental health services — and many already do, said Dr. Ted Epperly, president of the American Academy of Family Physicians.

It isn’t always as time-consuming as it might seem; some screening questionnaires can be filled out by patients in the waiting room, Epperly said. Doctors can easily spot any red flags.