Pope Francis remained in a 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 had breakfast, read the newspapers and followed Mass on television Sunday after a second night sleeping well at the

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 showed modest improvement in laboratory tests on Monday and resumed select work activities, the Vatican reported. The 88-year-old pontiff, who has been battling pneumonia in both lungs, was noted to have not experienced any further respiratory crises.

Pope Francis is being treated for double pneumonia and recent blood tests also revealed "mild renal insufficiency."

Monday marks Pope Francis’ 10th day in the hospital, making this equal to the longest hospitalization of his papacy.

The update comes after the Pope was said to be in a critical condition and was showing an "initial, mild" kidney problem.

Many who know him said that Francis, driven by a sense of mission and a discipline born of his early training, essentially worked himself into the hospital.