There’s fresh evidence that a lot of young people could be headed for heart trouble. A large study of preteens in Texas found that about one-third of them had borderline or high cholesterol when tested during routine physical exams.

The results seem to support recent guidelines that call for every child to have a cholesterol test between 9 and 11 — the ages of the 13,000 youths in this study. Many doctors and adults have balked at screening all children that young, but researchers say studies like this may convince them it’s worthwhile.

“A concerning number of children” are at risk of heart problems later in life, and more needs to be done to prevent this at an earlier age, said Dr. Thomas Seery of Texas Children’s Hospital and Baylor College of Medicine.

He led the study, which will be presented at an American College of Cardiology conference in Washington this weekend.

Estimates are that by the fourth grade, 10 to 13 percent of U.S. children will have high cholesterol. Half of them will go on to have it as adults, raising their risk for heart attacks, strokes and other problems.

High cholesterol rarely causes symptoms in kids. Many genes and inherited conditions also cause high cholesterol but not obesity, so it can be missed especially in youths who are slim or athletic.

The new study involved children having routine physicals from January 2010 to July 2011 at the largest pediatric primary care network in the nation, more than 45 clinics in the Houston area. One-third were Hispanic, about one-third were white, and 18 percent were black. About one-third were obese.

Unhealthy total cholesterol levels were found in 34 percent. LDL or “bad cholesterol” was borderline or too high in 46 percent, and HDL or “good” cholesterol was borderline or too low in 44 percent. Just over half had normal triglycerides, another type of fat in the blood.

Boys were more likely than girls to have higher total cholesterol, LDL and triglycerides, Seery said. Hispanics were more likely to have higher cholesterol and triglycerides.

“I would hope that data like these would get the attention of general pediatricians,” because many cases of disease are being missed now, said Dr. Elaine Urbina, director of preventive cardiology at Cincinnati Children’s Hospital Medical Center.

She was on the expert panel appointed by the National Heart, Lung and Blood Institute that wrote the screening guidelines issued in 2011 and endorsed by the American Academy of Pediatrics. They call for screening everyone between age 9 to 11 and again 17 to 21.

“Very few people know their entire family history,” and many forms of high cholesterol occur in people who are not obese, so screening is needed to catch more cases, she said.

High cholesterol doesn’t necessarily mean the child needs medicines like statin drugs, she said. The guidelines stress diet and lifestyle changes as the first step.

Online:

Screening guidelines: http://www.nhlbi.nih.gov/guidelines/cvd—ped/index.htm

Cholesterol info: http://tinyurl.com/23dtxvo