CAN GERALDINE FERRARO -- or any woman -- function as effectively as a man as vice president or president of the United States? This is one of the great whispered questions in this election year, and behind it, I think, is a lot of emotion and concern about an issue that has never been publicly confronted in this country: the relationship between female biology and the prudent exercise of political power.

This issue is buried in such casual remarks as, "If something happened to Mondale, she would be president, and I don't want that -- because she is a woman," which is what a salesman said while trying to sell me jewelry. And in the comment, "I'm not ready for a woman president," which is what a 68- year-old woman friend confided to me. It was also embedded in the exchange at Yummy Yogurt where three men debating politics at lunch complained loudly that Ferraro "didn't earn the nomination; it was given to her." And it helps explain the remark by a congressman friend of Ferraro that she is "hot-tempered." I think if he had been talking about a man with the same temperament, he would have said, "You don't mess with him."

But this is 1984 and it has been 14 years since Edgar Berman, Hubert Humphrey's physician, declared that women were unfit for certain jobs because of their "raging hormonal imbalance." He argued that women's physiology and psychology -- especially the menstrual cycle and menopause -- limit their potential for leadership.

Such openness now is unthinkable -- except when it slips out, as it did in a recent Boston radio show, when a woman caller demanded to know "what business a woman has in the White House" and whether the 48-year-old Ferraro has "been through menopause yet." Most comments on Ferraro and whether she has the emotiona stability to handle the job she's seeking are coded to sound more socially acceptable.

Catherine East, a retired Labor Department executive who has been active in the women's movement and political campaigns, also believes that is the subliminal message in much of the anti-Ferraro feeling.

"They are saying that the finger on the button shouldn't be a woman's finger, because they think women are unstable," East said. "That is at the bottom of many antifeminist views."

Such thinking isn't new, East said. "It can be traced back in history . . . . There has always been a certain amount of suspicion of women based on the fact that they have menstrual periods."

Ironically, 1984 has also become what might be called "the year of pre-menstrual syndrome," a disorder that afflicts several million women and is tied to the menstrual cycle.

PMS, as the experts call it, shouldn't be confused with menstrual discomfort. It is more severe and disabling than the occasional headche or slight irritability that many women experience just before the start of their cycle and which can be relieved with traditional medications. PMS afflicts its victims with powerful mood swings and sometimes-painful physical symptoms, all of which begin some time before the menstrual period starts, and end with the period itself.

There has been a rash of medical research and publicity on PMS in recent months.

Yet no one knows exactly how many women have PMS. Some experts estimate that 3 to 5 percent of women are affected so seriously that it sometimes interferes with their lives. That works out to as many as 3.4 million women in this country. But other experts say that up to 90 percent of women experience PMS symptoms occasionally but not so seriously that it interrupts work and social routines.

Georgetown Universtiy Medical School professor Estelle Ramey questions the idea that PMS affects that large a percentage of women at one point or anther. Absenteeism among women workers, she points out, is no greater than that of men doing the same job. "And if that is the case," she said, "then it is ridiculous to talk about 90 percent of women being incapacitated every month."

Yet PMS makes me and many other women nervous -- the more so now that we have the first woman candidate for vice president. We generally are unwilling to accept the traditional notion that a woman's emotional behavior is a function of her monthly cycle. And we typically don't want the power structure -- mostly male -- to use the menstrual cycle difficulties experienced by some women as proof that all women are inferior, unbalanced, and incapable of performing certain jobs.

In the past, feminists have dealt with PMS by pretending that it isn't a problem, at least not for many women. I understand why they do that. Sexist barriers remain, and I don't want PMS used to prop up what's left; I don't want PMS used as a weapon against women.

None of that alters the fact, however, that there really is something called PMS that interferes with the lives of several million American women. Nor does it help the millions of other women who don't have PMS but who suffer from PMS stereotyping.

PMS is an ambiguous -- even mysterious -- disorder that is difficult to diagnose because of the absence of knowledge about its cause and effect on victims. Previously discounted by doctors as a problem that women had to bear because they were women, PMS only now is being recognized by the medical community as a serious and legitimate disorder with many symptoms, including depression, irritability, water retention, sleepiness and a craving for chocolate and starchy food.

What distinguishes PMS from anything else that might cause those symptoms is timing. The symptoms typically appear after ovulation, which takes place about 14 days before the menstrual period begins, and then disappear after the start of the flow. No proven treatment has been found for PMS. But researchers at the National Institute of Mental Health are now working to define PMS and determine effective treatment for those with serious problems. Since the program began two years ago, Dr. David Rubinow, who is directing the PMS research, has concluded "there is an indeterminate percentage of women who have PMS, and there may be some for whom this condition can interfere with their ability to conduct their lives."

Some women who have been diagnosed as having PMS say that there are times before their period starts that they become so depressed and feel so anti-social that they want only to go to bed and stay there until the ordeal has passed. And they often do stay in bed longer, because of the drowsiness that can accompany PMS.

"Half a month, I was a different person," said one professional woman in the NIMH program.

"It starts with depression, then extreme irritability and intense fatigue. Walking for 10 minutes is a supreme effort. And here is mental confusion. Thoughts don't come quickly, and there is a mental block. My brain goes from operating on automatic to operating on manual, so I have to think through everything I do."

During the past year, there has been no shortage of publicity about PMS, which has been featured in everything from "Teen" magazine to "Science 84." But PMS remains a taboo subject for many people. Women -- particularly older women -- are often uncomfortable talking about it. Margaret Donkle, a Washington consultant who specializes in social problems such as teen- age pregnancy, feels she knows why.

After spending weeks learning about it for a paper she planned to write, Donkle found that she had so many internal conflicts about PMS that she had difficulty doing the paper. "I had a very hard time in my own head trying to sit down and write something that explained that PMS is a real medical issue that should be addressed in a sensible way that helped women with PMS continue normal day-to-day functioning," Donkle said. "At the same time, I wanted to write something that didn't play into the attitude that women are weak, that being sick is in your head and that women are unreliable because of raging hormones."

In the end, Donkle "came out thinking PMS should be treated as a health problem that you try to find remedies for and that you make minor accommodations for . . . but it shouldn't be used as a reason to exclude women from jobs and opportunities."

Over lunch one day, a colleague and I tried to analyze why PMS is such a powerful issue. We concluded that it is because it raises questions that reach beyond the state of our health. Like AIDS, which mostly afflicts homosexuals, and herpes, which is spread by sexual contact, PMS fairly bristles with questions about sexuality and social behavior. My colleague put it this way:

"PMS resonates with issues that cut into the most sensitive and emotional areas of our mind and that force us to think about how we view ourselves sexually, how others view us, how women are different from men, what that difference means and whether it is important or not."

But what makes PMS particularly frustrating, says Georgetown Medical School professor Ramey, is the way it is sometimes used against women.

"If you want to use something to show that you haven't discriminated against women -- that God did it -- if you want to use it as a club to beat women, like that idiot Berman did, then you can do that," she said. "If you want to use PMS to confirm your prejudices against allowing women into decision-making roles, then of course you latch onto it and you use it."

For Kathy Macoughtry, a 38-year-old nurse who lives in Laurel, PMS is a very personal issue, because she has been trying to cope with it in her own life since she was a teen-ager.

Macoughtry was brave enough to talk on the record about her experiences with PMS because she tnks it is time that women with the problem speak out and force a public debate. That could hasten a solution, she said.

She said that her symptoms begin to appear in mid-cycle, about 14 days after one period has ended and about 14 days before the next one starts. The problems accelerate about five days before her period and then disappear after her period starts.

She suffers from breast tenderness, water retention, cravings for chocolate and salty foods, lack of coordination, sleepiness, and dizziness. "I have given up horseback riding at those times, because I can't control the horse," she said. That decision came after she had suffered several spills.

At the worst times, she experiences "a personality change and I become extremely depressed and paranoid." She says that if she and her husband are invited to a party that happens to fall on what she knows will be a bad day for her, "I may go . . . but I don't enjoy it . . . because I have no toleration for people and I seem to want to stay away from them."

Macoughtry, who has been married for 13 years, says that her husband can chart her moods by the calendar. "That used to make me angry, because I didn't want to admit that PMS could cause that much of a problem for me," she said.

Now she is willing to acknowledge that she does have a problem with PMS and she is pleased that it is getting attention in the medical community.

"What bothers me most is that most gynecologists are male, and they don't understand what this is," Macoughtry said. "They say, 'Honey, this is something you have to put up with' and they treat you like a little girl. It is very frustrating. At least NIMH is going about this in the right way to try and find out what it is and how to treat it."

Macoughtry also had an opinion on the thorny question of whether women with severe PMS are so incapacitated that they shouldn't be allowed to hold some jobs.

PMS doesn't disable all women equally, she aid. Some who suffer from severe cases are able to function normally despite the problems, but some others are not, she said. "Someone could have PMS to the extent that they shouldn't be president . . . shouldn't be in the position of making a decision about which button to push for the bomb," she said.

"But there also are some men who shouldn't be president because they aren't capable of doing the job," she said. "So I don't think sex should have that much to do with it. It should be based on their capability, psychologically and physiologically, and that goes for both sexes."

My own inquiry into PMS led to these conclusions:

PMS is a sexist issue in the sense that all women suffer from the myths and distortions surrounding it.

PMS is a real problem for several million women and treatments should be found to enable them to lead normal lives. Meantime, some understanding of their plight would be appropriate.

Anyone with serious PMS problems isn't likely to have the enery or the inclination to run for president, or any other competitive position. For one or two weeks a month, women with serious PMS prefer to be at home resting rather than be out soliciting votes, shaping public opinion and debating the state of the economy and the possibility of nuclear war.