U.S. Secretary of State Hillary Clinton was hospitalized Sunday after doctors discovered a blood clot during a follow-up exam related to a concussion she suffered this month, her spokesman said, according to CNN.
She is expected to remain at New York Presbyterian Hospital for the next 48 hours so doctors can monitor her condition and treat her with anti-coagulants, said Philippe Reines, deputy assistant secretary of state.
"Her doctors will continue to assess her condition, including other issues associated with her concussion," Reines said, according to CNN. "They will determine if any further action is required."
Clinton, 65, was suffering from a stomach virus earlier this month when she fainted due to dehydration, causing the concussion.
Clinton spent the holidays with her family last week after working from home.
Her health kept her from testifying on December 20 to U.S. lawmakers about the attack on the consulate in Benghazi, Libya, on September 11.
The assault, in which the U.S. ambassador and three other officials were killed, sparked a political firestorm, and Republicans criticized Clinton's absence last week, calling on her to testify in January.
Clinton, who is due to step down from her post in early 2013, also stayed away from the White House when President Barack Obama nominated her replacement, veteran senator John Kerry.
She issued a long statement paying tribute to her successor, and the State Department has regularly assured the public that Clinton continues to work from home, but that has not prevented questions over her three weeks of absence.
State Department Spokeswoman Victoria Nuland has categorically denied suggestions from some observers that Clinton may be faking her illness in a bid to avoid testifying on the Benghazi inquiry.
Such claims were "completely untrue," Nuland said. "We've been very clear from the beginning that she had a stomach virus, an ugly stomach virus. She got very dehydrated. She fainted. It was later discovered she had sustained a concussion."