CHICAGO Reuters - High blood pressure among children and adolescents, a growing problem linked to increasing juvenile obesity, often goes undiagnosed in the United States, according to a study published on Tuesday.

This is dangerous, as high blood pressure can quietly damage the organs, especially the kidneys, the researchers reported in this week's Journal of the American Medical Association.

High blood pressure, or hypertension, often signals another disease in children, like endocrine disorders, kidney or heart disease.

Researchers at Case Western Reserve University in Cleveland examined more than 14,000 young people ages 3 to 18 and found 507 cases of hypertension. Nearly three quarters of that group, or 376 cases, had not been diagnosed despite at least three previous medical checkups.

An estimated 3.6 percent of the children had high blood pressure, within the range found in other studies, Dr. Matthew Hansen and colleagues found.

They suggested that electronic medical recordkeeping could be upgraded to better diagnose the problem by comparing the findings of earlier checkups, even though juvenile hypertension is difficult to confirm because it varies by sex, height and weight.

"Identification of elevated blood pressure in children meeting prehypertension or hypertension criteria is important because of the increasing prevalence of pediatric weight problems," the researchers wrote.

"If abnormal blood pressure is not identified by a patient's pediatric clinician, it may be years before the abnormal blood pressure is detected, leading to end-organ damage," they added.

The researchers said electronic medical records have the potential to be programmed to automatically "review current and prior blood pressures, ages, heights, and sex to determine if abnormal blood pressure criteria had been met."