Guidelines spelling out who should get cholesterol tests fail to identify two-thirds of children who really have unhealthy amounts of the fatty substance in their blood, a study suggests.

The findings bolster arguments that all youngsters should be tested to determine which face an increased risk of heart disease, said Dr. Dennis Davidson, director of preventive cardiology at the University of California, Irvine."We found that using the existing guidelines for (cholesterol) screening, we identified only one-third of the children with blood cholesterol already at a level undesirable for adults and certainly undesirable for kids," Davidson said Monday during the American College of Cardiology's annual scientific session.

"With universal screening, we would detect all children in the upper ranges of high cholesterol and help families change their diet to lower the risk to the children," he said.