The Pentagon announced on Sunday that Defense Secretary Lloyd J. Austin III had been taken that afternoon to a military hospital to be treated for “symptoms suggesting an emergent bladder issue.”

Mr. Austin was taken to Walter Reed National Military Medical Center in Bethesda, Md., 2:20 p.m., a Pentagon spokesman, Maj. Gen. Patrick S. Ryder, said in a statement. He added that the deputy defense secretary and the chairman of the Joint Chiefs of Staff had been notified, as well as the White House and members of Congress.

General Ryder said Mr. Austin, 70, was “retaining the functions and duties of his office.” If required, he added, the deputy defense secretary, Kathleen H. Hicks, would assume those responsibilities.

The announcement appeared to be aimed at showing transparency around Mr. Austin’s medical condition and stressing the fact that multiple top officials across the U.S. government had been informed.

Mr. Austin came under widespread criticism last month when he went to the hospital for several days for treatment for complications related to a recent prostate cancer surgery. He had initially kept his hospital visit a secret from top administration officials, including President Biden, the White House national security adviser, the secretary of state and senior officials in the Pentagon, including those immediately under him in the office.

Mr. Austin also had not informed the president that he had undergone the original surgery in December.

Lawmakers called for the Pentagon to provide answers on why so many officials were kept in the dark. Mr. Biden said on Jan. 12 that he still had confidence in Mr. Austin. But when the president was asked whether it had been a lapse in judgment for Mr. Austin not to have informed him that he had been out of commission, Mr. Biden said “yes.”

Mr. Austin, a retired four-star Army general and former commander of the United States Central Command, had served in the military for more than 40 years when he took the top Pentagon job in 2021. Throughout his career, he has sought to avoid attention and has tried to keep many parts of his life out of the public spotlight.

General Ryder said the Pentagon would provide an update on Mr. Austin’s condition as soon as possible.