(LONDON) -- Queen Elizabeth left a London hospital on Monday after a stomach infection forced her to check in Sunday and cancel or postpone a week's worth of engagements.
The queen, 86, experienced symptoms of gastroenteritis and received treatment at London's Kind Edward VII Hospital, according to Buckingham Palace. The palace says she was in "good spirits" before her exit and all signs suggested that her illness was not serious.
The queen first fell ill on Friday but kept up her scheduled events through Sunday morning, after which she was driven to the hospital in a car, rather than an ambulance.
"This is a precautionary measure," a statement from the palace read this weekend. "She was not taken into hospital immediately after feeling the symptoms. This is simply to enable doctors to better assess her."
Gastroenteritis is an infection of the intestine and causes diarrhea and vomiting, according to doctors. It is usually treated with fluids, and symptoms often pass after two to three days, although the queen's age forced doctors to proceed cautiously.
"Age is a factor which makes us worry a bit more about when people have gastroenteritis, because it's more difficult for the body to maintain fluid balance. Once you get a bit older, your kidneys tend not to work as sufficiently," Dr. Anton Emmanuel, a gastroenterologist who works at Edward VII Hospital but is not treating the queen, told ABC News.
The queen held nearly a dozen engagements last week, and she takes pains not to have her schedule interrupted. She has cancelled only a handful of engagements over the years and has only visited the hospital about half a dozen times, according to local media.
She has cancelled or postponed a trip to Rome this week to meet the outgoing president of Italy, as well as a visit to a Royal Navy ship in London known as "The Queen's Frigate" on Tuesday, and a military celebration in Wales Saturday. It is unclear whether these engagements will be back on.
The last time the queen visited the hospital was December 2003, when doctors operated on her knee to remove torn cartilage.
The queen's husband, Prince Phillip, maintained his schedule, attending an event by himself on Monday. Prince William, the Duchess of Cambridge and Prince Harry were travelling back from Switzerland after attending a friend's wedding.
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