Every American should have 11 thorough physical examinations between ages 6 and 60 as part of a national lifetime health monitoring program to prevent avoidable diseases, two of the nation's leading health authorities urged yesterday.

Congress should add such exams "immediately" to Medicaid programs and employers should start adding them to health benefits, said Dr. Lester Breslow and Anne R. Somers in the New England Journal of Medicine.

Like many other authorities, they question the value of the long-recommended annual physical for everyone because, they say, it has become too expensive, considering the few treatable or preventable ills it usually finds.

But Breslow and Somers are among the first to suggest an alternative schedule designed to produce a maximum payoff.

Americans should get top-to-toe physical at ages 6, 9, 13, once between 18 to 24, again at 30, then one every five years until 60, they said. After 60, they wrote, healthy people should be examined every two years.

Everyone over 50 should get some simple tests, like tests for high blood pressure and some cancers, they added.

But many widely accepted recommendations call for more testing than needed, they concluded. Between ages 18 and 39, for example, they recommended a dental exam and tooth-cleaning once every two years, and from 40 on yearly instead of the usual advice to "see your dentist twice a year."

Breslow is a professor of public health at the University of California at Los Angeles and a former California health commissioner. Somers is a professor of community medicine at New Jersey-Rutgers Medical School.

The country often talks about preventing illness but gives it low priority, they complained. A modest cost-effective program could be provided for everyone for about $7.50 to $15 a year, they estimated.

They said they hoped a set of "prudent" health examinations and measures like shots could be made part of future national health insurance, but meanwhile some state health commissioners might push such experiments, they suggested.

They quoted a Preudential Insurance Co. vice president as writing that "I see no problem with having [such] benefit included in group insurance provided by employers," though state or federal laws might be needed to mandate it.

Dividing the life span into periods, "based on changing life styles, health needs and problems," Breslow and Somers recommended:

Four medical visits for every healthy infant during the first year of life.

A visit to the doctor for every child at ages 2 to 3 and again at school entry.

Complete examinations at ages 6 to 7 and again at 9 to 10, then another at 13.

Just one complete physical for the healthy young adult sometime between the ages of 18 and 24.

Two visits at about ages 30 and 35, now "including tests for hypertension, anemia, cholesterol, cervical and breast cancer and instruction on self-examination of breasts, skin, tests, neck and mouth."

Complete physicals at ages 40, 45, 50 and 55, then every two years from ages 60 to 74, and thereafter once a year with "professional assistance with family relations, and preparations for death, if needed."

For all these periods, Breslow and Somers specify required shots and any health education the doctor should give - for example, advice "as needed" on nutrition, exercise, job, sex, marriage, contraception, alcohol, drugs, smoking and driving.