Teresa Heinz Kerry, who was hospitalized Sunday after suffering seizure-like symptoms, is in fair condition and improving, a spokesman for her husband, Secretary of State John Kerry, said Tuesday.
Her condition was upgraded from serious to fair on Monday.
Doctors have ruled out several possible triggers for the seizure-like symptoms including heart attack, stroke, or a brain tumor, spokesman Glen Johnson said in a statement.
Heinz Kerry was initially hospitalized on Nantucket Island in Massachusetts Sunday while vacationing with her husband and was later transferred to Massachusetts General Hospital in Boston for further tests.
"The well-wishes have been humbling and overwhelming, including tweets and Facebook postings; flower arrangements and offers of food; and messages of comfort from other [Massachusetts General Hospital] patients, former staff, Senate and House colleagues and members of the Executive Branch, as well as many dear and longtime friends and the Secretary's 2004 presidential campaign team," Johnson said.
"The family has also been touched by messages and phone calls from leaders in foreign governments who know and have worked with the Secretary and Mrs. Heinz Kerry," he added.
Kerry plans to return to Washington later Tuesday to kick off a previously scheduled economic and strategy meeting between U.S. and China before heading back to Boston.