What's likely to be the biggest medical breakdown of the decade?

The forecasters ought to swallow their disbelief and consider the so-called doctor glut, because, contrary to the wailings of the health care mandarins, it could be the most important therapeutic development since penicillin -- if it's played right.

The odds are that it won't be, given the latest addition to the ample literature on the feared surplus, delivered last week by a government-appointed committee that conducted the most comprehensive study of the subject so far. Known as the Graduate Medical Education National Advisory Committee, it concluded, like many of its predecessors, that most fields of medicine are en route to having too many practitioners. Overall, it reported to Patricia Harris, secretary of health and human services, that the doctor excess will number 70,000 by 1990 and 145,000 by the year 2000. To prevent this oversupply, it recommended the shrinking of the incoming freshman medical classes, a ban on adding medical schools to the nearly 130 in operation and further restrictions on the admission of foreign-trained physicians.

What it didn't report is that there's no political feasible way to stop the glut, but that the country can make good use of it.

The hefty cost of medical education -- the true burden is over $20,000 per student per year -- is only a minor part of the rationle for the proposed cutback. What mainly inspires concern about the surge of graduates, now running at over 16,000 a year, is the fixed belief that medical practice has become detached from supply-and-demand economics. The observed effect, at least so far, is that doctors not only receive high incomes just be bing in practice but that they also generate large expenditures for hospital care, drugs and other supplies and services. This thesis, which has become unquestioned gospel among health planners, leads in lock step to the congenial conclusion that the route to cost control is through enrollment control.

Overlooked in the easily written prescription for curtailing the availability of medial education is that doctoring is so highly esteemed and earnestly pursued as a profession -- for money-making, prestige and humanitarian reasons -- that all relevant political currents in recent years have favored more rather than less.

For example, at enormous cost and despite the abundant supply of covilian schools, Congress has given the military its own full-fledged medical school, the Uniformed Services University of the Health Sciences, in Bethesda. Three years ago, administration efforts to close it down for money-saving reasons were angrily rebuffed on Capitol Hill.

Even with the doubling of medical enrollments in the United States during the past two decades, the yen for the M.D. is so strong that some 5,000 Americans are, at great expense and inconvenience, studying medicine aboard, with hopes of eventually getting licensed here. Several years ago, congressmen responsive to the pleas of some of the parents slipped through an amendment requiring American medical schools to serve some transfer slots for those students. The prideful "My son, doctor" (or daughter, now that medical schools have rediscovered women) reflects a cultural passion that will not easily tolerate faraway political decisions to raise the already high barriers to medical education.

What's noteworthy is that even in Britain, where physicians' income under the all-embracing National Health Service are middling by British pay standards, medical schools are oversubscribed by qualified applicants.

Since the glut is unstoppable, or nearly so, why not benefit from it? With most urban ghettos and many rural area unaquainted with the feared surplus, this is a good time to expand incentives for the new crop of physicians to do service there. Such an inflow of physicians is already reported to be happening spottily as choice locations become saturated.

Nonetheless, the rich-poor disparities in the availability of medical services in most big cities persist as a gory disgrace; now that the medical troops are becoming available to do something decisive about it, why not do it?

As for doctors' running up the national medical bill just by being there, that's probably been the case so far. But the new abundance of medical manpower provides an opportunity to re-attach medicine to supply-and-demand forces. The key element, of course, is the reimbursement system, which, under one or another insurance scheme, has generally paid whatever's charged and then covered any shortfall by raising premiums.

With the insurers encountering resistance to higher premiums, the doctor surplus provides a marvelous opportunity to get a grip on costs. The solution is prescribed fee scales, which organized medicine regards as the ultimate evil. But given the choice between a reasonable fee and nothing, those newly minted M.D.s will mainly opt for reasonable fee. Add in advertising for patients, and that unstoppable doctor glut can be converted to a blessing.