Francis is being treated for pneumonia, a complex infection and kidney problems that have left him in critical condition. He did some light work on Monday.

ROME — Pope Francis remained in critical condition Sunday and blood tests showed early kidney failure but he remains alert, responsive and attended Mass, the Vatican said, as the 88-year-old pontiff battles pneumonia and a complex lung infection.

Pope Francis was found to have pneumonia in both his lungs Tuesday and his condition remains "complex," the Vatican said in a health update on the 88-year-old pontiff who was hospitalized last week. The big picture: The pope was admitted to Rome's Agostino Gemelli Hospital on Friday with bronchitis symptoms and his treatment was changed after doctors found he had a polymicrobial infection of the respiratory tract.