Robert Byrd, the longest-serving senator in history, was admitted to a Washington-area hospital Tuesday after a fall at his home in northern Virginia.
The 91-year-old West Virginia Democrat was admitted to the hospital after blood tests showed his white-blood cell count was high, which raised the possibility of an early-stage infection.
"His doctors have determined that Byrd should remain in the hospital for antibiotic treatment and observation," said a statement from Byrd's office.
Byrd had been transported to the hospital after a minor fall at his home, spokesman Jesse Jacobs said. He suffered no broken bones or bruises.
Byrd has been in frail health in recent years and was hospitalized in May and June with dangerous infections. But he returned to the Senate in July to vote and earlier this month gave his first floor speech in months, where he talked about the passing of Sen. Edward Kennedy.
The statement said Byrd is in good spirits but that he was disappointed he was unable to come to the Senate for its official photo.