Is a child ever too young to have tonsils removed?

No, as long as the surgery is done in a reputable hospital with well-trained staff. In fact, in rare medical emergencies, even newborns have surgery to remove their tonsils and/or adenoids, the clump of tissue on the back wall of the throat.

These emergencies occur because newborns are "obligate nose breathers," which means they have to breathe through their nose until they learn, by six or seven weeks, to open their mouths if their nose is obstructed, said Dr. Gerald Healy, chief of otolaryngology at Children's Hospital Boston.

Once a doctor determines, by X-rays or by looking into the baby's nose with a tiny viewing tube, that the adenoids are so big that they block air flow, surgery can quickly correct this potentially life-threatening problem.

A generation ago, most older children had their tonsils and adenoids removed because of recurrent infections, says Dr. Mark Volk, an otolaryngologist at Children's and a member of the executive committee on head and neck problems for the American Academy of Pediatrics.

Now, the chief reason is upper airway obstruction, which often results in breathing problems during sleep. Typically, the signs include snoring, mouth breathing, and restless sleep. Because sleep-deprived children, unlike adults, often manifest sleep deprivation by hyperactivity during the day, many are misdiagnosed with attention deficit and hyperactivity disorder.

A large National Institutes of Health study underway at Children's Hospital Boston and elsewhere is designed to determine whether removing tonsils and adenoids from children between the ages of 5 and 10 with obstructed breathing improves learning and behavior. For more information on that study, contact Dr. Eliot Katz at eliot.kat@childrens.harvard.edu.

E-mail health questions to foreman@globe.com.