Five-year-old Monica Lewis of Silver Spring was admitted to Holy Cross Hospital yesterday so doctors and medical technology could perform the work her liver stopped doing more than three years ago.

No television cameras recorded Monica's arrival at the hospital in the arms of her father, though doctors say she is a leading candidate for a liver transplant similar to the one that captured the nation's attention last week.

"One doctor told us a week ago that she has two months to live," said Mike Lewis, her father. "We are at the point now where a transplant is the only way. Until then, we do what we can."

This week, Lewis, 35, and his wife Pat, 34, followed newspaper and television accounts of the liver transplant operation in Pittsburgh for 16-month-old Candice Thomas of Accokeek, Md., for whom President Reagan had made a personal appeal for donors. That request sparked an overnight surge in the number of offers to donate organs and enabled five other critically ill children in four states and a young Brazilian child to receive new livers.

The six U.S. children were reported in critical but stable condition yesterday, and the Brazilian child was in serious condition. Another child, 11-month-old Ashley Bailey, of Clyde, Tex., who was also mentioned in Reagan's July 23 speech, is still in critical but stable condition and awaiting a compatible liver at the University of Minnesota Hospital.

In his weekly radio address yesterday, Reagan thanked the nation for the response to his appeal.

For Mike and Pat Lewis, the sudden increase in infant liver donors and transplant operations was a bittersweet chapter in the unending and costly rounds of hospital visits, daily medication and fear for their daughter's life.

The Thomas case "was good in the sense that it shows there's hope, that children are finally receiving new organs," said Mike Lewis, a newsletter editor. "But it also makes me very uptight and nervous. There's a pressure you can never escape from."

"We live on tenterhooks," said Pat Lewis, who recently quit her job with a medical association to care for Monica. "Every time you hear about a child getting a transplant, you start wondering: Will Monica's come in time."

At the age of two months, Monica was diagnosed as having alpha-one-antitrypsin deficiency, an inherited genetic disorder that afflicts one of every 2,500 people. The condition has various side effects, and the most severe can include hepatitis or--as in Monica's case--cirrhosis, the severe scarring of liver tissue. The liver's vital functions include filtering poisonous body waste and converting food for the body's use.

The youngster's condition, which her parents monitor constantly and combat with five scheduled drug and vitamin doses every day, worsened in December and again in March.

In May, Monica underwent four days of tests at Children's Hospital in Pittsburgh. Dr. Basil J. Zitelli, a Children's Hospital staff pediatrician who screens transplant cases, confirmed that Monica is one of "several dozen" candidates for the complex surgery.

"Is Monica near the top of the list? I would have to say yes," Zitelli said yesterday.

Zitelli stressed, however, that the hospital's ranking of patients for transplants changes constantly, as patients' conditions improve or deteriorate. "The decision as to who gets a new liver is based on who is the most critically in need," Zitelli said. "The sickest patient is the one who gets the liver." Young organ donors are rare, he said.

Mike Lewis carries a paging device that physicians at Children's Hospital may one day use to summon him, his wife and daughter to Pittsburgh for a transplant operation. Several friends at the family's church, National Presbyterian in Northwest Washington, have placed their private planes on standby for the couple's use.

The Lewises praised Reagan for his help in the Thomas case, but said they also were frustrated by his appeal. "It shouldn't be necessary for the president to step in like that," Pat Lewis said, as she loaded the family car for Monica's brief stay at Holy Cross Hospital. "The technology for the liver transplant is there now. It just seems like all the other resources aren't."

Contributing to this article was Washington Post staff writer Sandra R. Gregg.