Diabetes is not the only “adult” disease on the rise in children and adolescents. High blood pressure has become more common as well, largely because of increased obesity in the young, although often an underlying – and treatable — disorder is the cause.
Experts say that neither parents nor their children’s doctors are sufficiently aware of this health problem and its potentially serious consequences, including lasting organ damage. Too often, these experts say, abnormally high blood pressure in children goes undetected or is noted but not taken seriously.
National guidelines state that blood pressure should be measured every year in children, starting at age 3. In general, blood pressures in children should be lower than in adults. In adolescents, for example, a blood pressure of 120 over 80 millimeters of mercury is considered to be pre-hypertension, a condition that sets the stage for full-blown hypertension.
Among children ages 3 to 18 over all, 3.4 percent have pre-hypertension and 3.6 percent have hypertension, doctors at Massachusetts General Hospital have reported. One recent study of middle-school and high-school athletes in Philadelphia found that 20 percent were overweight and 24 percent were obese, and almost 15 percent of the student-athletes had high blood pressure.
In adolescents who are obese, more than 30 percent of boys and between 23 and 30 percent of girls have pre-hypertension or hypertension, Dr. Margaret Riley of the University of Michigan Medical School and Dr. Brian Bluhm of Integrated Health Associates in Ann Arbor, Mich., wrote in American Family Physician. Yet in children 18 and younger, “the diagnosis of hypertension is missed in the majority of cases,” Dr. Goutham Rao, chairman of family and community medicine at University Hospitals of Cleveland, wrote last month in the journal Pediatrics.
“In three-fourths of children with pre-hypertension and hypertension the condition is not detected,” he said in an interview. Among them was a 13-year-old boy in Pittsburgh with a blood pressure of 180 over 100. No note was made in the child’s chart of his very seriously elevated blood pressure, and no follow-up was suggested to determine a cause and prescribe a remedy, Dr. Rao said.
A major barrier to diagnosis, he said, “is doctors’ lack of knowledge about how to treat high blood pressure in kids. The more doctors know about treatment, the more likely they are to make a diagnosis.”
Another longstanding obstacle for doctors is that the definition of normal blood pressure in children depends on a child’s sex, age and height, with pressures in the 90th percentile and above considered unhealthy. Full-blown hypertension in children is defined as pressures in the 95th percentile and above. For adults, only one measure is used to define high blood pressure. Advocates found that charts of normal childhood pressures displayed in medical settings were rarely consulted in the usual rush of a well-child visit, Dr. Rao said.
Electronic medical records, now used in many doctors’ offices, could overcome this barrier because they can calculate where on the blood pressure spectrum a child falls as soon as the reading is entered, and flag a problem immediately.
Parents, too, are part of the problem of missed diagnosis. “Parents have very little awareness that their children could have high blood pressure, and they fail to make sure the doctor checks it and tells them the result,” Dr. Rao said. “Parents should ask at every visit, ‘Did you check my child’s blood pressure, and is it O.K.?’”
A further problem is so-called white coat hypertension: If a child is upset or nervous in the doctor’s office, blood pressure may be higher than usual. Children should sit quietly for about 10 minutes before blood pressure is measured, with two more measurements taken if the first one is high. If all three readings are high, the child should return for follow-up visits; a diagnosis of elevated blood pressure in children depends on finding a high reading on three separate occasions.
Another option is to take ambulatory blood pressure measurements with a small device worn by the child for 24 hours that automatically records pressure every 20 minutes or so. If a child’s blood pressure is consistently higher than normal, it should be rechecked every six months.
Blood pressure is determined by the balance between the output of blood from the heart and the resistance to blood flow in the arteries. The greater the resistance, the harder the heart has to work to get oxygen-rich blood to the brain and outer reaches of the body. A major consequence of untreated high blood pressure in children is enlargement of the heart’s main pumping chamber.
Left ventricle hypertrophy, as this condition is called, “can develop in just a few years in children with hypertension,” Dr. Rao said. “If a child’s hypertension is detected and brought under control, the enlargement will regress. But if it’s not treated, it just gets worse” and can eventually lead to heart failure.
Other consequences of untreated hypertension in children include atherosclerosis, the arterial disorder that leads to heart disease and stroke later in life.
Identifying and correcting the underlying cause for a child’s hypertension is critical to correcting it and preventing serious consequences. In addition to obesity, which is perhaps the most challenging cause to reverse, disorders that can cause hypertension in children include a wide range of kidney diseases, pulmonary diseases, heart defects, hormonal abnormalities, obstructive sleep apnea, genetic disorders and the use of certain medications, as well as some over-the-counter and performance-enhancing drugs and nutritional supplements.
When being overweight or obese is likely to be the cause, lifestyle changes are the preferred route to lowering blood pressure. Dr. Rao recommends “establishing intermediate goals that gradually reverse a child’s risks rather than setting goals that are initially impossible” and can discourage further efforts.
The focus should include a lower-calorie diet that emphasizes vegetables, fresh fruits, fiber and nonfat dairy; a reduction in dietary salt; regular physical exercise toward a goal of 30 to 60 minutes of aerobic activity on most days; a limit of screen time and working toward a maximum of two hours a day spent on sedentary nonacademic activities.
If blood pressure remains high despite lifestyle changes, or if underlying causes of high blood pressure can’t be reversed, medications can help. Dr. Riley and Dr. Bluhm listed thiazide diuretics, angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, beta blockers and calcium channel blockers as “safe, effective and well-tolerated in children.”