WASHINGTON -- In the mornings, President Bush generally seems to be his usual self: chipper, rested, glowing with the pink bloom of health.
But by afternoon, the medication for his overactive thyroid begins to tire him. His face turns ashen, his voice grows raspy, his cheeks hollow. The dozen pounds he lost while his thyroid condition was at work makes him look shrunken instead of trim.
White House doctors say Mr. Bush is "on a satisfactory course" in the treatment of the hyperthyroidism that caused his heart to beat irregularly three weeks ago. But he's at a low point in the cycle, during which the hormone-producing function of the thyroid is declining but the substitute hormone treatments have not yet begun.
Meanwhile, the president -- who used to keep aides and reporters gasping for breath to keep up with his daily schedule -- is mostly chafing at the sidelines of his normal activity.
"He watched a wallyball game [at Camp David last weekend] and really wanted to play, but the doctors told him to wait a couple weeks," said a Bush aide. (Wallyball is a version of volleyball played on a raquetball court.)
Officials say Mr. Bush has been told that in only a few more weeks, he will feel completely back to normal.
Everything is "A-OK," the president told reporters at a picture-taking ceremony yesterday morning. He reported that the three specialists consulting on his case and chief White House physician Burton Lee had come in earlier to examine him and gave him "a clean bill of health."
Mr. Bush acknowledged that he was "tired yesterday," Monday, when he looked particularly wan and peaked standing next to German Chancellor Helmut Kohl at a late-afternoon news conference.
"But today I feel good," the president insisted.
Even under normal conditions, Mr. Bush is a man whose physical appearance changes radically depending on his sleep and exercise level.
"I've learned you can't tell anything much by the way he looks," said White House spokesman Marlin Fitzwater, who described the president as some days looking "10 years younger" than the day before.
The drug therapy he's undergoing aggravates that tendency, however, as Mr. Bush's hormone level changes, his doctors say.
On May 9, Mr. Bush swallowed his first dose of radioactive iodine in order to stop his overactive thyroid gland from pumping too much of the thyroid hormone into his system. He now takes iodine drops daily.
The radioactivity in the iodine is intended to destroy the thyroid's production of the hormone that controls metabolism functions, including the beat of the heart. Those functions are to be taken over by replacement drugs the president will be given once the thyroid stops producing.
After his examination yesterday, the president's thyroid function was reported to be moving into the low normal range, which may mean that treatment with the replacement hormone is a week or two away, according to Dr. Paul W. Ladenson, director of endocrinology at the Johns Hopkins University School of Medicine.
Assuming the hormone substitutes begin about the first of June, Dr. Ladenson said it was likely that Mr. Bush would feel completely back to normal by about the Fourth of July.
The medications Mr. Bush has been taking to control his heart rhythm have been cut back, and yesterday he had his first cup of caffeinated coffee since his wife, Barbara, knocked it out of his diet shortly after the first heart flutter May 4.
He began to ease back into his once-vigorous athletic schedule with a horseshoe match at the White House last night.