New York — High blood pressure is sending more and more children like 14-year-old Kyle Mutschler to the hospital, according to a new study published in the journal Hypertension.

Kyle has suffered from high blood pressure since he was 5 years old. "I can easily tell. I feel dizzy, (get) headaches, don't feel well," he said.

He has to watch every bite he eats.

"We really try to keep his sodium intake at 1,200 milligrams or less, which is an incredibly difficult thing to do on a daily basis," his mother, Lynette Mutschler, said.

When such precautions fail, children with high blood pressure are increasingly ending up in the hospital. The study found that such hospitalizations nearly doubled between 1997 and 2006. Those most at risk were children under 9 years old, boys and African Americans.

Hypertension in children "can cause damage, irreversible damage to the heart, kidneys and eyes and set them up for cardiovascular disease as an adult," said Dr. Rick Kaskel, chief of pediatric nephrology at Montefiore Hospital in New York.

The rise in childhood obesity might be one reason for the increase, experts said.

"Also there are unknown factors in the environment," Kaskel said. "They don't necessarily have to be obese if they are born with a certain genetic component or have been exposed to environmental stressors such as diet or lack of exercise."

High blood pressure can often go undiagnosed. It's recommended that doctors start checking a child's blood pressure at age 3.

Doctors still don't know what causes Kyle's high hypertension. He takes four medications, gets plenty of exercise and uses new technology to keep close track of his blood pressure.

"Through an app, it will take my blood pressure, show me what it is, and I can email it to my doctor and to my mom," he said.

Kyle is glad to be more independent, and his mom has peace of mind knowing that his blood pressure is in check.