BOSTON Sen. Edward M. Kennedy's hospitalization after a seizure stretched to a third day Monday is raising questions about the severity of his illness.
The senator's office announced that he is not expected to return to Washington this week, and a spokeswoman said the Massachusetts Democrat had not been available to take a call from President Bush earlier in the day.
"Take care of my friend," the president told Vicki Kennedy, who answered the call from the White House to Massachusetts General Hospital, according to Kennedy spokeswoman Stephanie Cutter.
There was no word on how long Kennedy, 76, would remain hospitalized. Physicians not involved in his care debated whether the length of his stay was an indication of something more serious or simply an outgrowth of caution in dealing with a prominent patient.
One neurologist said a patient coming in with the symptoms that have been publicly described could be released in a matter of hours after undergoing a series of brain and blood tests.
"In my experience, when people come in with a single seizure, if they can do the MRI and appropriate bloodwork in the emergency room, they're discharged from there," said Dr. Mark Schlosberg of the Washington Medical Center.
Dr. Steven Schachter, a neurology professor at Harvard Medical School, said diagnosis "is not always a linear process."
Schachter said doctors sometimes have to circle back to earlier test results as they glean new clues from subsequent tests or fresh elements of a patient's medical history. He said one major focus would be determining whether Kennedy actually had a seizure, and if so, whether it's the type of seizure likely to recur.
The liberal icon was admitted to Massachusetts General on Saturday after becoming ill following a walk with his dogs at his oceanfront home on Cape Cod.
No members of his family have spoken publicly about his condition, and a statement Saturday from his personal physician, Dr. Larry Ronan, contained the most spartan of details.
"Preliminary tests have determined that he has not suffered a stroke, and is not in any immediate danger," Ronan said Saturday. "Over the next couple of days, Senator Kennedy will undergo further evaluation to determine the cause of the seizure, and a course of treatment will be determined at that time."
Kennedy's office confirmed his likely absence from work after it was disclosed by several officials.
"He's doing well and anxious to get back to work. Doctors are still evaluating him and we expect the senator to remain in the hospital for a couple of days while they finish their work," according to a written statement. "It's likely the senator will take a few days off at home before returning to the Senate."
Previous statements have described the senator's visitors and the movies and television he has watched. No photograph of Kennedy has been released since he was hospitalized, although a request from The Associated Press was being considered.
Over the weekend, Sen. John Kerry, D-Mass., visited his colleague, but he declined public comment about his condition. Sen. Barack Obama of Illinois, the leading Democratic presidential contender, told reporters he was surprised by Kennedy's vigor during a phone call Saturday.
Sen. Christopher Dodd, D-Conn., said Kennedy's voice "couldn't have been stronger" when he called Sunday.
"My cell phone rang and I picked it up and here was this voice that sounded terribly familiar to me talking about how those nurses were picking on him up in that hospital. It had me laughing," Dodd told reporters.
"His voice was robust and strong and full of that laughter we've all heard a million times. He sounded great."
Kennedy appeared to have been the victim of a seizure, an electrical disturbance in the brain. Ronan and other physicians were conducting a battery of tests, the results of which may not be available until Tuesday.
Kennedy underwent surgery last October on the left carotid artery in his neck after doctors discovered a near-complete blockage that left him with an elevated risk of a stroke. The senator has since resumed a hectic schedule, including campaigning for Obama and bouncing between appointments on Capitol Hill and in Massachusetts.
Schlosberg, the Washington neurologist, said that if Kennedy were his patient he would investigate whether he suffered an undetected stroke during his surgery, since seizures can often come months after a stroke.
"Perhaps he didn't have any symptoms of a stroke at that time, but maybe it put him on the path to a seizure down the road," Schlosberg said. CAT scans, MRIs, blood tests and an EEG brain-wave test would also be used to search for evidence of a stroke, brain tumor or abnormal brain activity such as a seizure.
Schlosberg said seizures can also be caused by medication, undiagnosed diabetes or sudden alcohol withdrawal.
Doctors may be taking more time seeking a cause, he said, because they know there will be a public scrutiny of Kennedy's treatment.
John Roberts, chief justice of the Supreme Court, was hospitalized overnight last July after an episode similar to Kennedy's. Roberts previously had a seizure in 1993, so in a clinical sense, his second meant he had epilepsy a disease that occurs in those having two or more seizures in their lifetime.
AP special correspondent Dave Espo and reporter Andrew Miga contributed to this story from Washington.