Former US first lady Barbara Bush has been hospitalized in Houston for treatment of early signs of a "respiratory-related issue," her husband's office said on Tuesday.

"She is in great spirits, has already received visits from her husband and family, and is receiving fantastic care. Updates will be issued when warranted," the office of former President George HW Bush said in a written statement.

Barbara Bush, who is 88, was admitted on Monday to Methodist Hospital in Houston's Texas Medical Center, the statement said.