The wife of US Secretary of State John Kerry was rushed to a local hospital Sunday after falling ill and had been transferred and admitted to a larger Boston facility, a spokesman said.
Late Sunday afternoon Teresa Heinz Kerry "was taken by ambulance to Nantucket Cottage Hospital accompanied by her husband," spokesman Glen Johnson said in a statement.
Heinz Kerry, a multilingual philanthropist born to Portuguese parents in colonial-era Mozambique, arrived in a "critical but stable condition," the Boston Globe daily reported, quoting a Nantucket hospital spokesman.
"At this point, we are determining the next phase of her care." said spokesman Noah Brown.
But Johnson said Heinz Kerry was later transferred to "Massachusetts General Hospital in Boston, again accompanied by the secretary."
"The family is grateful for the outpouring of support it has received and aware of the interest in her condition, but they ask for privacy at this time."
Kerry, the 2004 Democratic Party presidential candidate, had been celebrating the long July 4 weekend with his family at their home on Nantucket Island, Massachusetts, on his first long break since he took over in February as the top US diplomat.
He and his wife, 74, have been married for 18 years. It is a second marriage for both of them. She has three sons and Kerry has two daughters.
Kerry, 69, has kept up a grueling schedule since succeeding Hillary Clinton as secretary of state and had been expected to return to the Middle East soon as he pursues a bid to relaunch Israeli-Palestinian peace negotiations.
He had traveled to Massachusetts after returning to the United States from a 12-day tour which had taken in several Middle Eastern nations, India and Brunei.
Kerry had come under some criticism in the US domestic media for not attending in person a White House meeting called by President Barack Obama on the day that Egyptian leader Mohamed Morsi was toppled. But he listened to the deliberations by phone, and has been in regular contact with his Egyptian counterparts.
Kerry is due to host a two-day strategic US-China dialogue in Washington on Wednesday and Thursday with his Chinese counterpart, but it was not known Sunday whether he would still be able to attend.
Heinz Kerry has rarely been seen at Kerry's side during official functions at the State Department, although she was present for his swearing-in ceremony and accompanied him on one of his early trips traveling to Istanbul and London, before dropping off the rest of the voyage.
A former interpreter at the United Nations, she was married to senator Henry John Heinz, the heir to the Heinz ketchup fortune, who was killed in a helicopter crash in 1991. She inherited many of his trusts and is very wealthy.
A committed environmentalist like Kerry, they had first met at an Earth Day summit in 1990. They then met again two years later in Rio for an Earth Day event, after Heinz's death.
In 2009 Heinz Kerry revealed she had been treated for breast cancer.