The nation's doctors hit town yesterday, looking to draw a little blood.

At a tough-talking press conference to kick off their final lobbying blitz for legislation to exempt doctors and other professional groups from antitrust review by the Federal Trade Commission, leaders of the American Medical Association:

* Described as "pure, unadulterated nonsense" and a "bunch of baloney" the claims that FTC actions against anti-competitive practices by medical societies drive down health care costs.

* Contended that this spring's 4-to-4 Supreme Court decision upholding an FTC order allowing doctors to advertise without interference from their medical associations has left patients at the mercy of "entrepreneurs and quacks."

* Compared the FTC to a "kangaroo court" where the same agency acts as accuser, prosecutor and judge.

* Described themselves as leaders in the field of medical cost containment, but warned that their efforts to tackle cost issues in concert with hospitals, insurers and health care users would be frustrated as long as "we have the FTC all over us like a rag."

* Insisted that the estimated $2.5 million that its political action committee will contribute to congressional candidates this year (likely making its PAC the nation's most generous bankroller of Congress) is totally unconnected to its lobbying effort on the FTC bill. It takes a "very callous and cynical view of Congress" to think that PACs, which are limited to giving a candidate $5,000 in a primary campaign and another $5,000 in a general election, can "buy votes," according to Dr. James H. Sammons, executive vice president of the AMA.

While AMA executives were holding forth for the press, 36 state medical society directors began fanning out on Capitol Hill to make last-minute appeals to House members. The FTC exemption issue is expected to come to a head in a House floor fight next week.

To the AMA, the issue sizes up this way: medical societies alone have the expertise to regulate the professional standards and quality of care offered by physicians. The only outside regulation should be in the hands of the Justice Department, using its tradional antitrust enforcement powers, or state regulatory bodies.

The opposition has been spearheaded by second-tier medical professional groups that compete economically with doctors (nurse-midwives and opticians, for example), as well as by business and consumer groups that want to bring down health care costs.

They say FTC scrutiny of medical societies has been invaluable, and cite such FTC actions as the elimination of bans on advertising, the successful challenge of boycotts by local medical societies of hospitals that hire salaried doctors at below-market rates, and the promulgation of rules forcing eye doctors to give their patients prescriptions, thereby allowing the patient to shop for competitive prices on glasses and contact lenses.

They also claim that state regulators have historically been sympathetic to the medical society, and that AMA is pushing for legislation that would weaken the antitrust enforcement powers of Justice against the doctors.

In the long lobbying battle over an FTC exemption, the AMA took a decisive early lead, but its momentum has slowed recently as the opposition has grown better organized and as James C. Miller III, the Reagan administration's appointee to chair the FTC, has steadfastly opposed the exemption.

The AMA has lined up 219 House co-sponsors for its bill. It biggest fear is that it will lose supporters to a compromise measure to be introduced next week by Rep. James T. Broyhill (R-N.C.) that would permit FTC regulation of the commercial aspects of the medical profession but not the quality of care. The AMA contends the two issues are inseparable.

At least one of the orginal co-sponsors of the AMA-backed bill, Rep. Norman F. Lent (R-N.Y.), is now backing the Broyhill proposal. Lent says that when he explains his change of mind to doctors in his district, they seem reassured. But the AMA leaders, he says, are "intransigent."

The AMA, meantime, says it is fighting so that "professionalism will not be extinguished while we are responsible for it."