DO WE Americans have a right to know whether our elected officials are phisically and mentally fit to serve us?

Such a right is still far from established. Many doctors are only too willing to obfuscate for their political patients, to remain uninformative or inaccessible or to tell the public so much less than the truth that they mislead us.

As Dr. William J. Curran, professor of legal medicine at Harvard University, wrote in the New England Journal of Medicine last September, doctors treating public figures "have sometimes imposed too impenetrable a barrier around the patients - a white gauze curtain - to the extent of actually distorting the true picture."

The recent death of Sen. Hubert Humphrey of Minnesota, a case in which the public knew so little for so long about his 10-year bout with cancer, has brought this point sharply home againg. But the Humphrey case is only the latest of several still in public memory, to say nothing of others more distant. There was the Eagleton affair, in which a man with a history of emotional breakdowns may might have become vice president without the public ever learning of his medical past. There was the time during during the Kennedy presidency when, in the midst of a crisis that could have led to nuclear war, the president was taking a medicine that often creates euphoria.

Such events prompt Dr. Joseph Fletcher, professor of medical ethics at the University of Virginia, to remark: "It seems absurd to have laws that requires candidates or public officeholders to disclose their bank accounts, but allow them to pursue office or function in office while secretly suffering illnessess that could interfere with their performance. I'd rather have a rich man, with some temptation to favor his investments, in public office than I would a man with a brain tumor."

Similarly, Dr. James Nicholas, who once treated President Kennedy, says: "It is appalling to have candidates running for office who have documented infirmities that they don't permit the public to know."

Harvard's Dr. Curran adds: "We need to begin to develop public policy and some kind of regular procedure" to give the public the facts about "the health of their officeholders . . . We need to think about putting into law such requirements . . . One place where we might start would be regular examinaions to measure the continuing capacity of those already in office." Melancholia and Migraines

THE QUESTION is not whether illness or disability should automatically disqualify a person from publlic office. Abran Lincoln suffered severe bouts of depression, known then as melancholia. Thomas Jefferson was often laid low with migraine headaches. Both Dwight D. Eisenhower and Lyndon Johson won election after suffering heart attacks, and John F. Kennedy's admirers would maintain that mede a better president with some adrenal insufficency than Richard Nixon did at the height of his health.

But the point is that informed voters, not officeholders, should be the ones to make the decision.

Sen. Humphrey told me himself in April, 1976: "I don't believe in having sick people in office, though I don't say a person can't have minor disabilities and serve his country well." But politicians, like the rest of us, are not inclined to face their own mortality, to accept deadly diseases as more than minor disabilities, or to relinquish their power, and for a long time Sen. Humphrey was no exception.

Understandable as it may have been, his long reluntance to lay bare all his medical records might have had serious consequences. If he had won the Democratic Presidential normination again in the summer of 1976, his illness would have left his party badly in the lurch. For once he checked into the Memorial Sloan-Kettering Cancer Center for drastic cancer surgery that October, just a month before the election, his race would have been ended.

As he said on that painful occasion: "There's no question that I would have had to step aside" as the candidate. That almost certainly would have thrown the race to Gerald Ford.

Yet even after that operation and after that statement by Humphrey, a Memorial Sloan -Kettering press release papered over the grim meaning of his advanced cancer. And when a few reporters explained that the press release meant a patient with Humphrey's condition had one chance in four of surviving five years, they were castigated by some persons close to Humphrey as heartless and misleading. These included the senator's personal physician, Dr. Edgar Berman, who called a Washington Post report "irresponsible" and "inaccurate."

CONSIDER the deaths of the Humphrey case. In June, 1937, when Humphrey was vice president, some red blood cells first showed up in his urine. As Dr. W. Dabney Jerman, his urologist, said later, that was "the beginning" of what turned out to be his fatal illness.

An examination a year later showed what was then termed a "dysplssia," or abnormality of his bladder lining. Although Humphrey was about to run for the presidency, scarcely anybody in the country was aware of his condition.

In the early 1970s most doctors began calling the type condition he had in situ carcinoma and talking it more seriously. Carcinoma means "cancer," and in situ means in a limited site, without the invasion of the surrounding area that sounds the greater alarm. Doctors differed, and still differ somewhat, on whether this condition should be attacked like a fully invasive bladder cancer. Doctors differed in the Humphrey case. But there was no public hint of this debate, though Humphrey by then was back in the Senate representing Minnesotans.

In 1972 Humphrey's doctors began regularly using an anti-cancer chemical - as a "precaution" or "presentative," they said four years later, when this first became publicly known. Over the years, in fact, the physicians who actually treated Humphrey - a team headed by Dr. Jarman - remained largely silent, leaving press statements chiefly to Humphrey's medical adviser and friend, Dr. Berman. Berman consistently issued rosy views.

In 1973 the doctors treated a "more potentially cancerous" change with X-rays. This was publicized. But through 1974 and 1975 there was no mention of any further life-threatening problem or the continuing chemotherapy, though in situ carconoma cells were still appearing in every examination.

The fact that Sen. Humphrey had been flirting with actual or incipient cancer since 1967 was finally discloced by him and his doctors in April, 1976. This was done only in response to a press inquiry. That January, as Humphrey's name came to the fore as a presidential contender, those close to him recall, Humphrey suggested to Dr. Jarman that an honest statement be prepared to answer any inquiries. Thus the statement was ready when The Washington Post inquired (though Dr. Berman still argued publicly that the in situ carcinoma it described was not significant).

That summer Humphrey kept emphasizing his "excellent health." But when Medical World News, a physicians' magazine, broke new ground by succesfully asking all the avowed presidential candidates for their medical records, Humphrey declined to release his because he had not formally declared himself.

That fall came his Memorial Sloan-Kettering cancer surgery. Some days later Dr. Willard Whitmore, the surgeon, issued the following statement:

"Sen. Humphrey continues to do exceptionally well in recuperating . . . The pathology report . . . indicates that the cancer was of low grade histologically, but had penetrated the bladder wall and involves some of the regional lymph nodes. A systematic regional lymph node dissection was performed. The margins of dissection were made clear by microscopic examination; no transsection of the tumor occured. There was no evidence of spread beyond the perimeter of surgery. Therefore, it is entirely possible that the surgery has been curative."

"Let Them Be Completely Candid"

AN ORDINARY reader might have interpreted such a statement as good news, meaning "they got it all." Wire services, TV networks and most newspapers indeed carried reports which said or implied that cheery outcome.

Only The Minneapolis Tribune, The New York Post and The Washington Post added the information necessary to make the meaning clearer: National Cancer Institute statistics show that in bladder cancer with lymph node involvement the five-year survival rate is only 23 per cent, whether all the obvious cancer is removed or not. Hubert Humphrey, of course, remained an individual to whom the statistics might or might not apply. But the Memorial doctors knew they were dealing with an alarmingly advanced case of a particularly recalcitrant type of cancer.

Humphrey, too, knew these facts and, according to a former Humphrey aide, he often told his staff: "Let the doctors, not the public relations people, make all the statements. Let them be completely candid. Nothing else will be credible." That he or his staff or his doctors did not always meet this goal may speak in part of politics, in part of human hesitation when an ugly disease must be faced.

And the evasion had not yet quite ended by then. Last August - when Humphrey entered the University of Minnesota Hospitals for what doctors there felt was certainly a further growth of his malignancy - the university's first statement, prepared by a Humphrey aide, told the public he was merely "accomodat[ing] his vacation" by having a "checkup" and continuing his chemotherapy in Minnesota instead of Washinton.

This bald evasion deeply disturbed the university surgery chief, Dr. John Najarian. Najarian told a Humphrey aide that if he was expected to tell the public anything less than the truth, he would withdraw and let someone else do the surgery. He did not withdraw and he told the fuller truth: that Humphrey's cancer was "inoperable" and "terminal."

This was one of two recent cases of notable candor. Another doctor early last year insisted on giving the public the facts in a sentitive political case. The patient this time was Maryland's malfeasant governor, Marvin Mandel. A sudden stroke or apparent stroke had raised serious questions about his ability to stand a second trial after the first ended in a mistrial. His reported illness aroused skepticism among many persons who were convinced Mandel had found a new way to avoid facing justice.

A murky or overblown medical report might have helped Mandel avoid the second trial that ended his political life. But before even examining him, Dr. Marvin Korengold, the Washington neurologist consulted by Mandel's family doctor, told the governor that if he entered teh case, he would be candid with the public no matter what he found. Dr. Korengold was candid. He said Mandel had had a stroke but would in time be able to stand trial. Bot truth and justice were satisfied. Historical Evasion

UNFORTUNATELY, however, such candor historically has been the exception, not the rule. President Grover Cleveland underwent cancer surgery on a yacht in New York harbor so that the news, so he said, wouldn't affect the stock market. Woodrow Wilson suffered a physical collapse in September, 1919, and a stroke a week later. For more than a year the nation was run in large part by his wife while Wilson's disappearance was only vaguely explained.

Americans learned of Franklin Roosevelt's failing heart and advanced hypertension only after his death. Dwight Eisenhower's physicians were generally candid about his illnesses, but John Kennedy never admitted that he had Addison's disease, conceding only to a onetime "adrenal insufficiency," which means the same thing. Nor did he disclose that he was taking steroids, which can make the taker unnaturally euphoric, and was taking them at the time of the Bay of Pigs and Cuban missile crisis.

Dr. Nicholas, the New York orthopedic surgeon who later gained attention as custodian of Joe Namath's knees, wrote the facts about Kennedy (as an unnamed former patient) in the Archives of Surgery in 1955. Another doctor who knew Kennedy said to me a few years ago: "I treated him when he was a senator. I took care of him in moments of adrenal crisis. Throughout his campaign when there was more and more evidence that he was being treated with steroids, one could not help but wonder what kind of mental decisions he might make and about his emotional states."

Lyndon Johnson showed us his operative scar after his gall bladder operation and carried a copy of his electrocardiogram to show he had recovered from a heart attack. He did conceal the removal of a skin cancer, a highly curable one common to sun-beaten Texans.

Only this winter Sen. George McGovern disclosed his psychiatric consultants' reactions when they learned that his running mate, Sen. Thomas Eagleton, had a history of mental depression and hospitalization serious enough to require electro-shock therapy on two of his three stays. In his autobiography, "From Grassroots," McGovern writes that Dr. Karl Menninger reluctantly advised him that "for the interest of the nation . . . you can afford no risks and I would therefore hope and you would ask Mr. Eagleton to step down."

In this case as in others, the facts had long been concealed from the public. McGovern writes that "when [Eagleton] left for the Mayo Clinci in 1966 in a serious mental depression that resulted in weeks of hospitalization and electro-shock treatment, the story his office released was that he was at . . . Johns Hopkins . . . for treatment of a gastric disturbance."

When president Roosevelt's physician, Adm. Ross McIntyre, was asked by the press about Roosevelt's health shortly before FDR's reelection to a fourth term, he said it was "that expected of a man in his sixties" except for "a little sinus trouble." The press was successfully dissuaded, sometimes in force by the Secret Service, from ever photographing FDR sitting in his weekchair, moving laboriously on his crutches or, more often as the years went by, being carried bodily from place to place.

There is no doubt that Eagleton's withdrawals as vice presidential candidate in 1972 helped prompt all the avowed presidential and vice presidential candidates in 1976 to agree to bare their medical records to Medical World News. Jimmy Carter not only released his, but insisted that all six contenders for the Democratic vice presidential slot do the same. One result was the first disclosure that then Sen. Walter Mondale had hypertension (successfully controlled by medication).

President Ford became the first president in office to reveal all the details of his routine physical - this, again, to Medical World News. But President Carter, who was so medically candid a candidate, has so far permitted the release of only an unspecific, 130-word press release - one with no corroborating details or statistics - on his latest physical, despite a request for a full report by the same medical magazine.

What of lesser officials? In 1972 New York Democratic Rep. William F. Ryan denied reports that he had cancer while running for reelection. He died during the campaign. In 1974 Manhattan District Attorney Frank Hogan was hospitalized for a "checkup," or so he said. He too actually had cancer. He was reelected - but had to resign because of his illness. The governor, not the voters, chose his successor.

Last September the suggestion that all major federal appointees and candidates for Congress routinely disclose their medical histories was made by Federal Judge Frank M. Johnson Jr., who had just been nominated to head the FBI. Ironically, he made it while he was recovering from surgery; when he was slow to recover, he had to give up the job.

Harvard's Dr. Curran thinks that even the Johnson suggestion might not be enough. What we need, he says, is "not just disclosure of the statement of a physician engaged by the patient" - or, in the case of a president, the statement in most instances of a military doctor - but "an independent, nonpartisan medical evaluation." Dr. Curran thinks such a requirement should be written into the law governing presidential succession, which now allows a president to make his own decision about his capacities.

The University of Virginia's Dr. Fletcher thinks doctors sometimes should go even further on their own. He believes that if a president or presidential candidate refuses to reveal "whatever information is relevant to the public's ability to form a judgment [on] whether he is competent to serve," the physician should speak up if the facts are "manifestly vital to the public's interest."

"When the greatest good of the greatest number is at stake, no individual's rights or interests should be allowed to dominate," he contends. "This is a problem that arises in medicine all the time. Sometimes the vell of professional secrecy has to be lifted to protect a family or the public."

Dr. Fletcher cites a case where secrecy should have been lifted but was not: "That of Winston Churchill. In the last year or more of his tenure as prime minister, his deterioration was both mental and physical. He was subject because of changes in his brain to all sorts of odd and outrageous behavior and ideas. The cabinet was puzzled and, because of respect for him, reluctant to act. Had Lord Moran, his physician, told them, 'He is a man suffering from a physical breakdown and unreliable to rely on,' they would have acted. Interestingly, it was Mrs. Churchill rather than Lord Moran who finally told them he was really not competent." When Private Matters Become Public

SOME DOCTORS probably will continue to obfuseate or remain silent on demand. They might note that the American Medical Association's Judicial Council, the main arbiter of American medical ethics, has said a doctor may not discuss a patient's health with the press without the consent of the patient or a representative.

But the council added: "Public figures are in a different position, in regard to publicity, than the ordinary citizen. One of the penalties of being in the public eye is the automatic surrender of a portion, at least, of one's right of privacy . . . A patient by virtue of his position may have an obligation to others. If so, he must know and discharge that obligation (to the electorate or to the stockholders or to others to whom he is responsible). The physician should insure the accuracy of any authorized report . . . A physician may, within the limits of good taste, encourage the patient or his family to state the cause of illness . . . when this information is requested by a bona fide representative of the press."

By Dr. Najarian's and Dr. Korengold's examples last year, physicians shouls not only encourage disclosure, but in some cases refuse to take the patient without it. The doctor who does less may cure his patient but damage the public and injure his own reputations as well.

Dr. Curran does not think Americans would lightly or foolishly turn thumbs down on an officeholder or seeker for any but the most serious mental or physical reasons. He says: "The knowledge and sophistication of the American public about disease and treatment is much more sophisticated than we sometimes think. We're living with a good deal of chronic disease in this country. And the public tends to be eternally optimistic."

But whatever the decision, it should be the public's.