Va'Sean Duvall is a skinny 17-year-old who stays busy with an after-school job, choir rehearsals and school drama productions. On the surface, he doesn't fit the mold of someone - older, obese and inactive - who would be at risk for high blood pressure.

Yet he's among as many as 4 million children in the United States estimated to have hypertension, a figure that has grown fivefold in the past generation, according to Johns Hopkins researchers. It's a condition that doctors often fail to diagnose and one that leaves children - particularly African-Americans - at risk for serious heart problems, says a recent Hopkins study.

Doctors have known that a rising number of children are at risk for high blood pressure, and they think the nation's surging child obesity rate is a prime cause. But now, researchers are trying to learn more about the specific heart problems triggered by high blood pressure and hope to sound the alarm on the importance of catching hypertension early.

"We need to do a better job at increasing the public awareness, and we need to look at what are the barriers of physicians in recognizing high blood pressure in a clinical setting," said Dr. Tammy Brady, a pediatric nephrologist at the Johns Hopkins Children's Center and one of the study's authors.

Brady and other researchers found that black children with high blood pressure are more likely than other children to develop a thickening of the left chamber of the heart. Known as left ventricular hypertrophy, or LVH, the condition can lead to heart failure, rhythm abnormalities and death.

Of 139 hypertension patients ages 3 to 21 in the Hopkins study, 60 percent of the black subjects developed LVH, compared with 37 percent for those of other races.

"It's concerning that the prevalence is higher in the African-American population," said Dr. Cozumel Pruette, a kidney specialist at Hopkins Children's Center and the study's lead author. "Practitioners need to realize that and need to follow those children closely."

Researchers don't know why the disparity exists. Black children with LVH also tended to have higher cholesterol levels and a higher body mass index, putting them at greater cardiovascular risk, Pruette said. Since the study was among the first to look at racial differences and was done with a small sample, she said, more research is needed to understand why black children are especially vulnerable.

Still, Pruette stresses that all children with untreated hypertension could be at risk. Even those with mild hypertension can develop LVH.

Doctors are still learning the intricacies of the illness in children.

"It's been recognized in adults for several decades, but I think that our attention to LVH in children has probably lagged," said Dr. Susan Mendley, assistant professor and director of pediatric nephrology at the University of Maryland School of Medicine.

Brady, at Hopkins, recommends that when a doctor discovers one episode of elevated blood pressure, the child should be monitored and have further tests to determine if there are underlying causes of the hypertension. Children should have blood and urine tests to rule out kidney problems, which can cause hypertension. And doctors should do an eye exam to rule out eye problems that can trigger hypertension.

In addition, children should also receive an ultrasound of the heart, known as an echocardiogram, to check for LVH, she said. "It's a mistake not to do it," she said.

But some pediatricians say the extensive ultrasound may not be necessary for every child with elevated blood pressure. First, parents should be advised to encourage their child to exercise and limit salty foods, which can cause high blood pressure, said Dr. Charles Shubin, director of pediatrics at Mercy Medical Center in Baltimore.

"How much do you subject a larger population to get that if there is very low incidence of that problem?" he said. Of course, he said, if blood pressure is consistently high, doctors should order tests.

Brady says monitoring is critical because hypertension strikes some children who have no underlying health problems, making it difficult to detect without further tests. If the high blood pressure is severe, children can have symptoms such as bloody noses, headaches and shortness of breath.

"But often, hypertension is silent in kids," said Brady. "The kid looks fine; the kid seems healthy and has no complaints."

Pediatricians tend to carefully screen obese children and those with a family history of hypertension. But for other young patients, doctors may not do blood pressure readings at all, despite recommendations that screening begin at age 3, said Brady, who has researched why doctors miss high blood pressure. And some doctors do not take proper blood pressure readings, which is admittedly a tough task with a squirming child; Brady recommends taking three blood pressure readings during a visit and averaging them.

A 2007 study by Harvard researchers found that doctors fail to diagnose high blood pressure in more than three-quarters of children with the problem.

It can be difficult to spot kids with hypertension. Healthy pressure depends on a child's age, gender and height, so that "normal" is often a moving target.

"To a pediatrician in a busy clinic, there are so many things they are expected to do in a visit, so sometimes, they eyeball it," Brady said.

Many parents believe high blood pressure is an adult problem, and they are often shocked to learn their children have hypertension, Brady said.

Duvall's grandmother, Paula Duvall of Baltimore, had no idea children could struggle with high blood pressure. And when she learned of her grandson's diagnosis, she immediately began fretting about the child she has raised since he was a toddler.

She knows the risks of hypertension; she has the condition, and so does Duvall's grandfather. "That hurt me, because I know what it's like," she said.

Doctors detected Va'Sean Duvall's hypertension when he was admitted to the hospital this year for an asthma attack. Diagnosed with asthma at age 2, he's had attacks so severe he's been to the intensive-care unit more than a dozen times, and he takes numerous medications to keep the asthma controlled.

His lung doctor referred him to Brady after noticing the youth's blood pressure was consistently high. Other tests showed swelling of his heart muscle - an indicator of LVH. Brady put him on adult medicine, one pill a day.

"The high blood pressure medication, to add that on - that's really scary for me," Paula Duvall said. "Kids, they don't like taking medication, and it's hard for him sometimes, since he's been taking medication his whole life."

Va'Sean Duvall has taken the diagnosis in stride. His mind is set on studying math this fall at Coppin State University, with the ultimate goal of becoming a Broadway performer.

"It gets overwhelming sometimes," he said. "Sometimes taking medicine puts people down. But I say, 'Well, what can you do? Without medicine where would we all be?' "

Hypertension in children

* Affects as many as 4 million children in the U.S.

* More frequent and more severe in black families than in whites.

* If untreated, can lead to heart failure and death.

* Risk factors include obesity and having a parent with high blood pressure.

* All children age 3 and older should have annual blood pressure checks. Doctors should evaluate the readings with charts that indicate normal blood pressure by age, gender and height.

Sources: Johns Hopkins Children's Hospital researchers. American Heart Association

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