Michael K. Deaver, the former White House deputy chief of staff, says he kept his alcoholism secret from his closest associates for years and that Nancy Reagan expressed relief when told of it.

"Thank God!" Deaver says the first lady exclaimed when he telephoned her with the disclosure from an alcohol treatment facility in Maryland in 1986. "Thank God, that's what it is," she continued.

Deaver, who recounts the exchange in the current issue of Life magazine, says he pleaded with Mrs. Reagan to understand that his alcoholism was "a terrible thing."

"No, it is a disease, and one you can handle," he says she replied. "I was worried sick that you might have cancer. This one you can cure."

Deaver says that in his final months at the White House, he was consuming "up to a quart" of scotch and three rolls of breath mints a day.

The magazine hit the newsstands yesterday, and one of its most eager readers is expected to be Whitney North Seymour Jr., the independent counsel who is currently prosecuting Deaver in U.S. District Court here on five counts of perjury. Seymour had sought to gain an advance copy of the article, taken from Deaver's upcoming book, "Behind the Scenes," but his request was rejected.

Deaver left Georgetown University Hospital yesterday morning after undergoing surgery Friday for a separate medical problem, a kidney stone that forced a week's delay in his trial. Assuming that Deaver, 49, makes as quick a recovery as his doctors have said is possible, his lawyers have said the trial should resume tomorrow morning.

Deaver has raised his alcoholism as part of his defense to the charges that he lied to a congressional subcommittee and a federal grand jury that investigated the once-flourishing lobbying business he formed after leaving the White House in May 1985. He has not talked publicly about the illness, and the Life magazine article marks the first time he has discussed it.

In the Life excerpts, Deaver says his condition was one secret he managed to keep "in a town not famous for for keeping a secret." No one outside his family and his doctor -- neither the congressional committee nor the prosecutor that investigated him -- knew of his condition, he says.

Deaver also says in the article that he quickly realized that one of his biggest mistakes as a lobbyist was to agree to pose for a Time magazine cover holding a telephone inside a limousine. Nancy Reagan called him immediately after the magazine appeared and told him, "Mike, you made a big mistake," Deaver writes.

"She was telling me that I had violated one of the first rules of the Washington game: Try not to enjoy too much success too soon," he says.

The article recounts Deaver's two decades of work for Ronald Reagan and how he was hailed at the White House as "Magic Mike" and "the Vicar of Visuals" for his work controlling Reagan's image.

It also recounts that Nancy Reagan held the hand of her father for almost an hour after he died and that the Reagans, who belonged to a Presbyterian church in Los Angeles, did not know how to take communion at an Episcopal church in Middleburg, Va., during his 1980 campaign.

Both the Reagans dipped their communion wafers in a chalice and, instead of eating them, dropped them into the cup, Deaver writes. "I watched the minister move on, shaking his head as these blobs of gunk floated in the chalice."