Washington ? At least one out of every five U.S. teenagers has abnormal cholesterol levels, boosting the risk of heart disease, federal health officials reported Thursday.

A national survey of blood cholesterol levels in American teenagers found that more than 20 percent of those ages 12 to 19 had at least one abnormal blood fat level and the rate jumped to 43 percent among those adolescents who are obese.

Although previous studies had indicated the abnormal cholesterol levels — once a condition thought isolated to people who were middle-aged and elderly — had become a problem among the young, the new data documents the problem on a national level.