President Reagan's temperature was back to normal yesterday morning after rising for a second time Saturday night to the "moderate" fever level, and doctors said the temperature elevation might be a result of damaged tissue and coagulated blood along the path of the bullet wound in his chest.

Asked if the fever indicated the presence of an infection, Dr. Dennis O'Leary, spokesman for George Washington University Hospital, replied: "If it does, we sure can't find it."

O'Leary said the hospital's infectious disease specialist found "no significant bacteria" in multiple urine, blood and sputum cultures, and other tests showed no evidence of abscess in the wound suffered by the president in an assassination attempt last Monday.

The hospital's "working hypothesis" is that Reagan's fluctuating body temperature -- "moderate" rises to between 101 and 103 degress Fahrenheit, compared to the normal body temperature of 98.6 degrees -- is a result of damaged tissue and coagulated blood particles in his lung, according to O'Leary.

He said the president's white blood count "has been consistently elevated," but that the count was "compatible" with the trauma accompanying the wound and subsequent surgery.

The president continues to receive chest therapy, which mainly involves coughing to keep the lung clear and expanded. O'Leary said further bronchoscopies -- such as was performed Friday night to remove "several small bronchial plugs" and dormant blood from the president's lung -- are "not immediately contemplated," and that the president's physicians, at this point, "are engaged in patient and watchful waiting."

The patient, meanwhile, was described as alert, in good spirits and doing a little "watchful waiting" of his own, getting a briefing from Vice President Bush on increased Soviet military movements near Poland as well as the particulars of Secretary of State Alexander M. Haig Jr.'s trip to the Middle East.

"We updated the president on the world situation," Bush told reporters after his 10-minute visit yesterday. "We talked about Europe and Lebanon . . . and that's about all I care to say."

Asked if he had told Reagan about Soviet President Leonid Brezhnev's trip to Czechoslovakia, where communist leaders supposedly will discuss the Polish crisis, Bush said: "He is fully on top of the situation."

Also visiting Reagan yesterday was Vernon Jordan, president of the National Urban League, who was the victim of a shooting last May 29 in Fort Wayne, Ind. Reagan, who had visited Jordan during the civil rights leader's convalescence, recalled that visit yesterday with a quip: "This is a switch," the president told Jordan.

"It sure hurts getting shot," White House aides quoted Reagan as saying to Jordan during their seven minutes together yesterday.

"It hurts like hell," Jordan reportedly responded.

Jordan also gave the president a bit of medical advice, based on his own experience: "The secret is, I did everything I was told. I never fussed." e

White House press secretary James S. Brady, the most seriously injured person in the assassination attempt outside the Washington Hilton Hotel, continued to show steady progress yesterday. Doctors said Brady is eating solid food and sipping water and that his speech is getting more sophisticated. sAccording to the White House medical bulletin yesterday, Brady -- whose nickname is "the Bear" because of his girth -- told his wife, Sarah, Saturday night: "The Bear certainly was in the wrong place that time . . . ."

GW hospital officials said yesterday that Secret Service agent Timothy J. McCarthy "continues to make excellent progress" in his recovery from a stomach wound suffered in the shooting. District of Columbia police officer Thomas K. Delahanty, recuperating from a neck wound at the Washington Hospital Center, was listed in good condition yesterday.

Meanwhile, Justice Department officials said yesterday that tests to determine the mental state of John W. Hinckley Jr., accused in the assassination attempt, have "stopped the clock" on Hinckley's prosecution.

Department spokesman Thomas DeCair said the court-ordered psychiatric examinations of Hinckley at the Federal Correctional Institution in Butner, N.C., should delay his case for about 90 days. The time-consuming battery of psychiatric tests takes precedence over Hinckley's constitutional right to a speedy trial, DeCair said.