A group of Western doctors, headed by Houston heart surgeon Michael DeBakey, examined the deposed shah of Iran today for the first time since he flew here from his Panamanian exile.

Egyptian security forces, meanwhile, drew up two armored personnel carried and deployed additional troops at the Cairo hospital where the fallen monarch is awaiting surgery to remove his spleen, which his doctors believe to be cancerous.

There was no official explanation for the intensified security at the hospital by Army troops and Interior Ministry police. But observers recalled that Iranian revolutionaries have repeatedly threatened to assassinate the shah, and Iranian President Abol Hassan Bani-Sadr recently said he must "return to Iran or die."

Two medical bulletins said the Western doctors had conferred with their Egyptian colleagues treating the shah and that together they "decided to continue the same treatment as before." The bulletin did not specify what the treatment was.

Both communiques were signed by Maj. Gen. Sabri Ismail, commander of the Nile-side Military Hospital in the southern Cairo suburb of Maadi.

DeBakey refused all comment on the shah's condition.

Soldiers chased away photographers and television cmaeramen who had been standing by in vain outside the hospital. An Egyptian official said the shah and President Anwar Sadat had personally requested that they be cleared out so the former monarch could "get a breath of fresh air."

The security precautions also included a ban on visits to the hospital by families of other patients, enforced by uniformed officers carrying submachine guns.

It was not known whether there had been any threats against the shah since his arrival. Observers said Egyptian security frequently is slow to move and could simply be taking up positions decided when the shah checked into the hospital Monday morning.

Sadat visited the shah this morning for the second time since his arrival on a chartered plane from Panama, underlining again his welcome to the former Iranian ruler who had been refused refuge in other countries.

His gesture has drawn criticism in the Arab world and some opposition at home. Egypt's two leftist parties have condemned it in statements and Islamic fundamentalist students protested it yesterday at Cairo University. But Sadat has insisted that true Moslem principles of hospitality and gratitude toward a friend compel him to receive the homeless Iranian ruler, who came to Egypt's aid after this country's 1973 war with Isarel.

DeBakey flew into Cairo last night with a six-man team of specialists expected to perform the spleen operation on the shah at the Maadi hospital. Carboard boxes labeled "human blood" and medicines were seen unloaded from the chartered airliner that brought them from the United States.

Egyptian doctors on the 15-man team assigned by Sadat to care for the shah were quoted in Egyptian newspapers today as saying his temperature had dropped and the operation can be performed within a few days. One doctor told the official Middle East News Agency it would take place Saturday and that empress Farah, advised of her husband's condition, had given approval for immediate surgery.

Egyptian officials said earlier fears of a shortage of the shah's B-negative type blood have dissipated. Some of the blood, relatively rare here, was said to have been brought in on DeBakey's plane. Egyptians, including members of the hosptial staff, also were called in to donate in preparation for the surgery.

Sadat has asked to be kept closely informed of the shah's condition, officials at the presidency said. This reflected his evident resolve to show the shah the best hospitality Egypt has to offer, despite whatever complications may ensue in obtaining release of the American hostages in Tehran or in his own standing in the Arab world and at home.