All the tests given Maryland Gov. Marvin Mandel at Johns Hopkins Hospital found not disease that would explain his month-old ailment, according to Hopkins sources.

The tests on Mandel -- who was discharged from the Baltimore hospital Wednesday for rest at home -- were "entirely negative," a source said. The examinations included sophisticated brain Xrays as well as laboratory tests.

The negative results, combined with the fact that Mandel showed genuine physical symptoms such as impairment of functions on his right side, led the Hopkins specialists to conclude that a small stroke was the most likely cause of the ailment.

"What the evidence supports at this point in time is that he probably did have a circulatory" ailment, probably a stroke, said Dr. Marvin Korengold, the Washington area neurologist who was a consultant in Mandel's case.

A stroke means some kind of blockage or other accident among the blood vessels of the brain. In many such cases there may be few signs or no signs on whole batteries of tests.

"The absence of evidence can tell you something too," Korengold said. "In this case there has been an absence of any other information," most importantly, no evidence of any kind of cancer or tumor.

In a curt, six-paragraph statement issued Wednesday seven Johns Hopkins doctors led by Dr. George B. Udvarnelyi refrained from stating just what their new tests showed. They said only that they failed to "disclose the cause" of Mandel's trouble.

But they concluded that Mandel did have a "left hemispherical disturbance of the brain of definite organic," meaning physical, "origin." They said the possibility of some cause that cannot be pinpointed yet "still exists."

However, they said their "working hypothesis" -- or tentative disagnosis --was that Mandel may indeed have had a minor stroke that by this week was showing "significant" improvement.

This largely repeated the conclusions reached by Drs. Perry Hookman, Korengold and Udvarhelyi when Mandel was a patient at Prince George's General Hospital before his transfer to Hopkins last week. Those conclusions, too, were reached by observing Mandel's symptoms -- weakness of face, arm and leg muscles on the right side of the body. Each side or hemisphere of the brain controls the body's opposite side.

Only one set of tests among many made by Hookman and Korengold --the electroencephalograms or brain wave recordings made at the private Neurology Center in Bethesda -- had shown a mild abnormality.

Mandel had been transferred to Johns Hopkins primarily for one added and crucial test: a cerebral angiogram, or dye injection to make the brain's blood vessels show on X rays.

If there had been a brain tumor or cancer, it would probably have shown up on those X rays, unless it was very early and small.

If it was a stroke, "the expected course is improvement and that improvement may be partial or complete," Korengold summed up.

"The governor has shown considerable improvement in a short time, assuming he actually had the stroke a few months ago. He waited some time, you know, before allowing himself to go to a doctor.

"These things can continue to improve for six months or longer. Hopefully, all the symptoms will clear. That's what every doctor wishes for every patient."

A weak but cheerful Gov. Marvin Mandel conferred with Lt. Gov. Blair Lee III and other associates at the Governor's Mansion in Annapolis yesterday, but Mandel apparently will not increase the limited work load to which he was restricted during his 23-day hospital stay.

During a 45-minute mid-day meeting between Mandel and Lee on the first full day at the mansion for Mandel since april 5, it was decided that the lieutenant governor would continue his status as "acting governor" in several areas, including the signing of about 130 bills at a ceremony at the State House on Friday.

Lee said the governor was "very happy to be home," and especially thankful to be relieved of "the endless series of tests," some of which were dangerous and painful, during his stay at Johns Hopkins and Prince George's General hospitals.

The governor is restricted to one trip a day up and down the stairs at the mansion, Lee said, and Mandel "doesn't expect to be in the State House much" during the month-long convalescence ordered by his physicians.

While Mandel may not cross the street to his office during his recuperation, Lee said that "for his own health the doctors want him to have a continuing supply of work to do, because that will be much better therapy than brooding about his health."

What work the governor takes on, however, "must not have a high stress factor," Lee said. Typically, Mandel will go over the hundreds of bills passed by the legislature and read various reports.

The doctors "don't want him to have a lot of visitors," Lee said. In addition to the lieutenant governor, other visitors at the mansion today were Alan M. Wilner, Mandel's chief legislative officer, Frederick L. Dewberry, his executive assistant, and Thom Burden, his press officer.

Mandel greeted visitors today in a lower-level day room, dressed in sports shirt and jacket. On occasions when he would get up from the wicker chair where he was sitting he walked slowly around the room, Lee observed.

At his side throughout most of the meetings today, as she has been since he was stricken was Mandel's wife. Jeanne. Several of the visitors today remarked that Ms. Mandel appeared to be quite fatigued, and even her voice reflected weariness from her long bedside vigil.

"The person who needs rest right now is Jeanne," said Lee, who said he suggested that "they reverse roles" so the governor can wait on her for a while. "She's been under a lot of stress," said Lee.