The National Institutes of Health's drug study program was not responsible for the death of a young volunteer who died in her sleep during an experiment there, according to the Maryland medical examiner's office.

Dr. Ann Dixon, assistant state medical examiner who performed the autopsy on 23-year-old Bernadette Gillcrist, said yesterday that recently completed tests indicated the volunteer died of natural causes on April 12.

"It's an unfortunate, natural coincidence-type death," Dixon said in a telephone interview. "I think that her environment had nothing to do with her death."

Dixon also said she was certain that Gillcrist died of cardiac arrest, brought on by repeated, self-induced vomiting. "I don't think it's anything other than a natural death."

Gillcrist, who had experienced two previous cardiac arrests and was revived each time, had been diagnosed as suffering from anorexia nervous, an emotional disorder that often causes the victim to induce vomiting in an effort to lose weight. The state of semistarvation produces electrolyte imbalance and below-normal potassium levels.

At the time of her death, according to an NIH official report, Gillcrist's serum potassium levels were below normal and similar to the levels recorded at the time of her previous cardiac arrests.

Although she had once been a patient at NIH, Gillcrist managed to hide her past medical history from hospital officials in order to participate in the study, for which she was to receive $800.

She was one of 20 volunteers being used to test the combination of lithium carbonate, an antidepressant, and AMPT (alpha-methyl-para-tryosine), an experimental drug. The study was to monitor the effects of the two drugs on sleep and mood patterns.

Although lithium carbonate can sometimes cause cardiac problems, Dr. Dixon said only a small amount of the drug was present in Gillcrist's blood.

"Lithium is there, but it's of no consequence. The amount is so little," Dixon said yesterday.

Although the drugs did not contribute to her death, NIH Clinical Center director Dr. Mortimer Lipsett said yesterday the hospital was still negligent in failing to determine that Gillcrist was not a "normal" volunteer. n

"The sleep lab technically violated hospital regulations by not calling up the volunteer's chart. They kept their own records," Lipsett said yesterday. t"Had they done that, the death could have been prevented."

Gordon Forrester, a lawyer retained by the Gillcrist family, said yesterday he will recommend legal action against the Bethesda research complex. Citing "several issues of negligence," including the fact that the sleep lab had no medical personnel on duty the morning Gillcrist died. Forrester said the lawsuit "will be substantial. It will be in the millions."

A senior nursing student at Catholic University, Gillcrist first volunteered for the drug study last December. At the time, she denied any past medical problems. But a check by the admissions officer revealed that Gillcrist had been hospitalized at the research center in 1976. The officer telephoned the sleep study, but the information was never passed on.

Whoever took it [the message] may have forgotten," Lipsett said yesterday. "We haven't gotten anybody to admit it."

By then, Gillcrist had already been participating in the first phase of the study, and had received $500. She needed the money, according to friends, for tuition to medical school.

"I'm sure the money is an inducement," Lipsett said, "but we couldn't get volunteers without it."

Gillcrest died in her sleep at 5:15 a.m. on April 12, NIH officials said. Although the sleep study technician noticed that the EEG used to monitor the volunteer's brain waves had gone "flat," the technician thought the machine had broken down, and did not try to arouse Gillcrist. Two hours later, the technician discovered the volunteer had died.

A report by NIH officials released last month concluded that had a nurse been present, "the gravity of the situation" might have been noticed sooner.

At the time of her death, NIH officials found dried vomitus in the volunteer's purse. It was learned that Gillcrist was trying to lose weight for her sister's coming wedding. The young nursing student had already lost about 20 pounds, family members said. Gillcrist did not tell her family or her psychiatrist that she was participating in the NIH study.

As a result of the death, the first serious mishap in the sleep lab's 25-year history, volunteers will now be more carefully screened for past medical problems, Lipsett said yesterday. NIH is also reviewing its payment scale for normal volunteers.

The sleep lab, which had been shut down since April 12, will reopen, Lipsett said. It is also likely, according to Dr. Robert A. Cohen of NIMH, that studies using AMPT -- which had been discontinued -- will be resumed.

A complete autopsy report on Gillcrist by the state medical examiner's office is scheduled to be released next week.