One in seven U.S. adolescents lacks health insurance, and Congress might consider immediately expanding Medicaid and taking other steps to improve young people's access to health care, a report said Monday.

"Conventional wisdom that American adolescents as a group are so healthy that they do not require health and related services is not justified," the Office of Technology Assessment concluded in its report.About 4.6 million of the 31 million Americans between ages 10 through 18 - or about one in seven - have no type of health insurance coverage, said the OTA, the analytical arm of Congress. Furthermore, one out of three poor adolescents do not have access to Medicaid, the report said.

Despite the general belief that most teenagers are in robust health, perhaps one in five U.S. adolescents have at least one serious health problem, the OTA found in a previous study.

Accidents are the leading cause of death among Americans between ages 10 to 19, followed by homicide, suicide, cancer and heart problems.

An estimated 5 percent to 10 percent of adolescents have a serious chronic physical condition such as hay fever, sinusitis, asthma, bronchitis or migraine headaches. In addition, it appears that about 30 percent of new gonorrhea cases and 10 percent of new syphillis cases occur among people ages 10 to 19.

To help more young people get proper medical care, Congress could require that employers provide health insurance for workers and their dependents or mandate an immediate expansion of Medicaid to include all poor adolescents, the OTA concluded.

Sen. Lloyd Bentsen, D-Tex., said although much remains to be done, he thinks some of the concerrns raised in the report have been addressed. In 1990, Medicaid eligibility was extended, on a phased-in basis, to all children up to age 19 in families with incomes below the federal poverty level, and a tax credit was set up to help families of "modest means" buy health insurance, Bentsen said.