Barbara Bush May Be Released from Hospital

March 30, 2010— -- Former first lady Barbara Bush is winding down her fourth straight day in a Houston hospital as doctors "narrow in" on a diagnosis of a mystery illness which has been plaguing her for about a week, according to a family spokeswoman.

"Methodist Hospital is going to put out a release tomorrow with her diagnosis," Jean Becker told ABC News this evening. "They have been sorting through test results and think they have narrowed it down."

Earlier in the day, Becker had said the hospital was "puzzled by the illness."

Doctors at Houston's Methodist Hospital have put Bush, 84, through a battery of tests.

Bush will not be released unless doctors "get a break," another family spokesman Jim McGrath had said yesterday. "She is in no pain, so there is no rush."

McGrath described the illness as not life threatening but would not go into further detail about the ailment's symptoms or her prognosis for recovery.

Former President George H.W. Bush drove his wife to the hospital near their Houston home on Saturday morning and has been with her everyday, Becker said.

Other members of the Bush clan, including son, Neil Bush, and daughter Dorothy Bush Koch have also visited. The other Bush children, including former president George W. Bush, have called to check-in on their mother every day.

Barbara Bush's medical history contains a number of conditions for which she has received treatment in recent years.

Just over a year ago, she underwent precautionary open-heart surgery at Methodist Hospital to replace her aortic valve with a biologic valve -- a procedure which the hospital said went "extremely well."

In late 2008, Bush was at the same hospital for abdominal surgery to treat an ulcer.

In 1989, she was diagnosed with a thyroid condition known as Graves disease which reportedly caused her to lose 18 pounds in three months.

Bush later began taking medication, including steroids, to treat the condition and in 1990, received radiation therapy for her eyes as part of her treatment.