President Bush's thyroid condition was diagnosed Thursday as Graves' Disease, and he was immediately treated with a radioactive iodine dose, his doctors said.

Once the doctors treat Bush's overactive thyroid, the president's tendency toward an irregular heartbeat will probably disappear, said Dr. Kenneth Burman, an Army colonel and thyroid expert from Walter Reed Army Medical Center.Graves' Disease is the same illness that caused eye troubles in his wife, Barbara.

"We anticipate that the president will be fully restored to his usual state of vigorous health very quickly," Burman said at a medical briefing at Bethesda Naval Hospital, where Bush underwent 21/2 hours of tests early Thursday.

He said it was "probably just a coincidence" that both Bush and his wife had the same condition.

Burman said the iodine treatment would begin to work immediately, but its full effects might not be felt for two or three months. In the meantime, Bush will receive a saturated solution of iodine for about two weeks to more rapidly restore normal thyroid activity.

Dr. Burton Lee, the White House physician, said Bush was "gratified" that his heart condition could be explained by the thyroid malfunction and that the problem could be easily treated.

"I'm very lucky," Bush told a Hispanic business group Thursday, "very, very lucky."

Lee said he was working with the White House to slow down the president's schedule in coming days.

"My tendency is to want to give the man a break," Lee said. "He's been through quite a lot."