Some 200 federal employes, including a White House employe, a staff member of the Joint Chiefs and a Secret Service technician, have been identified by the FBI as buying fake diplomas and degrees, according to a report by the House Select Committee on Aging released yesterday.

Raids on diploma mills by the Federal Bureau of Investigation have yielded the names of 7,400 people nationwide who have purchased credentials allowing them to work in professions as diverse as nuclear engineering, architecture, medicine and pharmacology.

"This is a startling indictment of the present system," Rep. Ron Wyden (D-Ore.) said, reacting to the report and testimony that studies indicate some of the 15,000 to 40,000 doctors who have failed qualifying exams in this country in the last decade may be practicing medicine anyhow. "Certainly every consumer in America has to be frightened . . . . The watchdogs have fallen asleep. Certainly the professional societies aren't policing their ranks."

Anthony Daniels, the FBI's deputy assistant director of criminal investigations, told the committee that the bureau has notified the inspectors general of federal agencies with employes whose names were listed in the records of the bogus diploma operations.

Kathleen Gardner Cravedi, director of the committee staff, said only two of the 11 agencies contacted, the Small Business Administration and the U.S. Postal Service, have begun investigations into the fraudulent credentials.

Of the 200 federal employes the FBI identified as having purchased sham degrees, 75 were employed by the Defense Department, according to committee staff member Peter Reinecke.

Col. William McLain, a Pentagon spokesman, said the agency's Defense Investigative Services "occasionally" has received FBI reports on the subject. There was no comment from the White House and Secret Service yesterday.

It is not illegal to purchase a bogus degree, but it can be a crime to use one, according to Jack Swagerty of the U.S. Postal Inspection Service.

Individual consumers and private employers are the chief victims of the thousands of Americans posing as professionals with the help of fake credentials, the committee was told.

Committee Chairman Claude D. Pepper (D-Fla.) recently became "Dr. Pepper" by paying $1,800 for a phony Ph.D. in psychology from a Columbus, Ohio, diploma mill. The head of that operation, Anthony Geruntino, who recently began a five-year prison term for mail fraud, told the committee that his firm had earned $2 million since 1980.

Fake credentials have been deadly for some.

Myrtle Reid, an 84-year-old California woman, died June 11 after an individual with apparently fraudulent credentials from a university in the Dominican Republic allegedly convinced her to stop taking her medications. According to Robert Hamilton, an inspector with the Santa Clara district attorney's office, the man was hired as a home health aide for Reid. Shortly before her death, Reid, who was mentally confused, adopted the aide and left him her $150,000 home and $140,000 in stocks.

"Myrtle's doctor of 20 years stated that 'taking her off her medications was like putting a .45 to her head and pulling the trigger,' " Hamilton testified. The aide has been charged with first-degree murder, grand theft by fraud and several counts of perjury, Hamilton said.

Medical credentials, because of the status and economic position they confer, are particularly coveted, the committee found.

A Nashville woman, identified only as Mrs. X, described how her former husband bought a medical degree for $8,000 and was hired at a North Dakota hospital in 1978 despite the fact he had not passed the required qualifying exams. She said he later practiced at a state hospital in Oklahoma until she notified authorities. He is currently serving a five-year sentence, she said.

New York licensing officials testified that police are searching for a fake architect who oversaw the construction of a New York City hotel and said that indictments are expected soon involving a Brooklyn medical diploma broker with 1,100 customers.

"We have licensed New York physicians who for a sum of money certified that these clients had completed clinical training," said Joseph Fisch, director of the state's Office of Professional Discipline. "Hospitals all across the country hired these people."

Fisch added, "The one glaring lesson learned is that no one should take documents pertaining to medical education at their face value." CAPTION: Pictures 1 and 2, "Mrs. X" says husband practiced medicine after buying a degree a for $8,000; Anthony Geruntino . . . ran $2 million credentials firm