Doctors at Massachusetts General Hospital on Monday upgraded the condition of Teresa Heinz Kerry from critical to fair, as they sought to determine what caused the leading philanthropist and wife of Secretary of State John F. Kerry to suffer a seizure Sunday at the family’s Nantucket home.
Heinz Kerry was rushed to Nantucket Cottage Hospital on Sunday afternoon, where she was stabilized before being transferred to Boston for a battery of tests that continued through Monday, according to several people close to the family.
“She is undergoing further evaluation, and Secretary of State John Kerry, her son, and other family members remain with Mrs. Heinz Kerry at the hospital in Boston, as they have been since she became ill,” said Glen Johnson, a spokesman for her husband.
He declined to discuss further details of Heinz Kerry’s condition or her activities over the Fourth of July holiday, which the family spent at their beachfront home, where the former Massachusetts senator keeps his yacht.
NBC News, quoting an unnamed medical source who treated her, reported Monday that Heinz Kerry had been afflicted by a “grand mal seizure’’ and that she had been breathing with the assistance of a respirator. Two people familiar with the situation but who were not authorized to speak publicly confirmed to the Globe that she had had a seizure but did not offer any further details.
Her hospitalization has prompted an outpouring of support, in the form of phone calls and messages from President Obama, Michelle Obama, and a string of foreign diplomats, according to aides.
“The family is touched by the outpouring of well wishes,” Johnson said in a prepared statement.
In addition to messages from Washington and Massachusetts, support came from Pittsburgh and Western Pennsylvania, where Heinz Kerry oversees the charitable Heinz Endowments.
While the endowments support causes across the globe, Heinz Kerry has focused much of her philanthropic efforts on helping the neediest and advancing the arts in her adopted home.
She moved to Pennsylvania in 1966 after she married her first husband, H. John Heinz III, the late Republican US senator who was killed in a plane crash in 1991.
John Heinz was great-grandson of the founder of the food conglomerate that bears the family name.
Through the Heinz charitable foundations, Heinz Kerry has been a benefactor of Pittsburgh’s ballet and sculpture gardens. She played a critical role in revitalizing the Pittsburgh riverfront and supporting the University of Pittsburgh.
At 74, Heinz Kerry’s pace has slowed some in recent years, particularly since she suffered from breast cancer in 2009 that required surgery and radiation treatments.
Heinz Kerry has also recently fulfilled some diplomatic duties on behalf of her husband, including attending the 90th birthday celebration for former secretary of state Henry Kissinger last month in New York, and sitting next to Great Britain’s Prince Harry at an event hosted by the British embassy in Washington in May.
As for trips with her husband, she has recently traveled with him to London, Istanbul, and Jerusalem.
She went to Nantucket early on July 3 with Kerry after he returned from an overseas trip. During the holiday break, various members of the family visited the vacation home on Hulbert Avenue.
Seizures — a misfiring of electrical activity sometimes affecting the whole brain and sometimes just a small part —
Other symptoms can include a loss of consciousness or a change in mental state, causing a person to “go blank” or become unresponsive, said Dr. Joshua Goldstein, director of the Center for Neurologic Emergencies at Massachusetts General, who was not involved in Heinz Kerry’s care and spoke only generally about seizures.
There are various causes of a seizure. Among them are brain infections and meningitis, or swelling of the brain. Metabolic abnormalities caused by dehydration can cause a seizure in someone who is otherwise healthy, while strokes or traumatic brain injuries also can lead to seizures. Brain tumors can be another cause.
The brain requires “such a complex network of signals firing all the time, that only the littlest thing can throw it off,” Goldstein said.
Secretary Kerry remained by his wife’s side Monday and aides said it was unclear how her ailment would affect his schedule in the coming days.
“He’s obviously concerned about the well-being of his wife, but comforted by the sound medical care she’s received,’’ Johnson said.Chelsea Conaboy and Noah Bierman of the Globe staff contributed to this report. Bryan Bender can be reached at email@example.com. Follow him on Twitter @GlobeBender