High blood pressure isn’t just a problem for grown-ups.

Five in 100 children have higher-than-normal blood pressure, according to the American Academy of Pediatrics. Usually, there is some underlying cause, such as an illness or other medical condition.

But for children 7 and older, half of all hypertension is caused by obesity, according to the academy, a rising concern as childhood obesity has doubled in the past 30 years, figures from the Centers for Disease Control show. Now, one-third of children and teens are obese or overweight, the CDC says.

At the recent Blood Pressure 4 Kids Fishing Derby at Cabela’s in Gonzales, 135 youngsters were screened, and 19 had higher-than-normal blood pressure and were advised to see a doctor, said Celeste Goodwin, president and founder of the Prairieville-based National Pediatric Blood Pressure Awareness Foundation, which sponsored the event.

“Just like an adult, if you leave hypertension untreated, it’s going to cause issues down the road,” said Goodwin. “It’s going to affect your heart. It’s going to affect your kidney function. No matter what causes it, your organs are going to be damaged from hypertension.”

Most children do not get their blood pressure checked regularly, even at the doctor’s office, Goodwin said.

“For many years, it was thought that hypertension was an adult-only condition,” she said. “It was not something that really affected children in the numbers that it does.”

Goodwin started the nonprofit foundation after her son, Matthew, now 12, nearly died from an undiscovered condition as a 4-year-old. Because his blood pressure had not been checked, doctors did not discover the illness.

When Matthew was 4, he had his tonsils removed and tubes put in his ears — both common procedures. The week before the surgery, during a pre-operation checkup, his blood pressure was high.

“It was a little elevated at that time,” Goodwin said. “The nurses dismissed it, saying he was anxious or nervous about the surgery coming up.”

About six hours after the surgery, he started vomiting and was rushed to the emergency room. His blood pressure spiked to 195 over 135, a dangerous level for anyone, especially a 4-year-old.

Over a few days, doctors ran tests and at Children’s Hospital of New Orleans. They found that Matthew had renal artery stenosis, a narrowing of arteries to the kidneys that causes high blood pressure.

Doctors bluntly explained that Matthew could have died of a stroke or a heart attack if the condition had gone undetected much longer. At 5, he was about to start playing sports, and a baseball or soccer game in the heat could have killed him.

“It gives me chills to think about what would’ve happened had we not found out about it,” Goodwin said. “You put him out in the heat in those conditions.”

Most pediatric high blood pressure is caused by a secondary condition — a heart defect, polycystic disease or a kidney disease like Matthew’s. Elevated blood pressure is a signal to doctors something is wrong.

In recent years, the American Academy of Pediatrics and the American Heart Association began recommending children get their blood pressure checked beginning at age 3, and more doctors are checking it regularly, Goodwin said.

The youngsters who came to the Cabela’s event also got to try their luck in a $10 fishing tournament. The foundation uses the money to hold blood pressure screenings in area schools. A screening and meet-and-greet with “Swamp People” reality television stars she held in Paducah, Kentucky, a couple of years ago drew 5,000 people, she said.

Her mission, Goodwin said, is to ensure other families do not have to be surprised by a major illness like Matthew’s. “We just knew this was not something we wanted another family to have to endure,” Goodwin said.

In most ways, Matthew lives a normal life. He sees a doctor regularly, takes a few pills a day and watches sodium in his diet. He hopes the blood pressure screenings like the fishing derby help more children stay healthy.

“Every time you do something like this,” Matthew said, “it’s a reminder that this is something positive that came out of me being sick.”