Increasingly parents ask me if their child has hypertension (elevated blood pressure). This question often arises after the nurse or physician repeats the blood pressure during a regular checkup.

In fact, we are seeing more cases of hypertension in children and young adults, mainly as a result of obesity.

Michael J. Campbell, MD, a pediatric cardiologist at Duke, gives us some tips on what hypertension is and how to prevent it.

-- Dennis Clements MD, PhD, MPH

Michael J. Campbell, MD

What is hypertension?

Hypertension is defined as an elevation in blood pressure above what would be normal for a person’s age, gender, and height.

Blood pressure is controlled by the arteries that deliver oxygenated blood from the heart to the tissues and organs of the body. Arteries have a circular layer of muscle within the wall of the vessel that can relax and constrict to control the pressure within the arterial system.

Hypertension occurs when these vessels maintain the pressure within the arteries at an abnormally high level.

How common is hypertension?

The incidence of hypertension increases with age. Hypertension is a common diagnosis in the adult and elderly population.

Historically, hypertension in children has been rare except for in children with certain heart, kidney, or neurological problems. The incidence of hypertension in children and young adults, however, is increasing. This is in large part due to an increasing prevalence of obesity in children.

Why is hypertension harmful?

Prolonged exposure to elevated blood pressure can damage organs. Nearly all organs of the body can be affected by prolonged exposure to elevated blood pressure.

Hypertension can cause the heart to work harder as a result of having to pump blood against higher pressure. This can lead to thickness of the heart muscle and heart failure. Coronary arteries can be damaged by hypertension and people with hypertension are at increased risk of myocardial infarctions, or heart attacks.

Elevated blood pressures can damage blood vessels within the brain, which places people at increased risk of strokes. The arteries within the kidney can be damaged by hypertension, leading to subsequent kidney failure. Hypertension can also damage small arteries within the eye, leading to vision loss.

How is hypertension diagnosed?

Hypertension is diagnosed by measuring blood pressure with a sphygmomanometer. This is a common instrument found in many physician offices. When blood pressure is measured a systolic and a diastolic blood pressure are recorded.

The systolic blood pressure is a measure of the blood pressure in systole, the phase of the heart cycle when the heart is contracting.

The diastolic blood pressure is a measure of the blood pressure in diastole, when the heart is relaxing. These numbers are represented as systolic/diastolic. Hypertension is diagnosed when these numbers are above normal for a person’s age and size.

In pediatric patients, normal blood pressures increase with increasing age.

What if my child has an elevated blood pressure?

A person must have an elevated blood pressure on three separate occasions to be diagnosed with hypertension.

One of the most common reasons for someone to have a high blood pressure at the physician’s office is “white coat hypertension.” If one is nervous or anxious at the time of the visit, then this can elevate blood pressure above normal levels. In these cases it can be helpful to obtain a blood pressure outside of a physician’s office.

If a person is diagnosed with hypertension, then the next step is to evaluate for causes of hypertension. A narrowing of the aorta must be ruled out by measuring blood pressures in both arms and both legs. Kidney disease is a cause of high blood pressure.

Laboratory evaluation including blood tests, urinalysis, and a renal ultrasound can evaluate for causes of hypertension.

Less commonly, diseases of the nervous system and adrenal system can cause elevated blood pressure and should be considered. Certain medications can also cause hypertension. People with obesity are more likely to have hypertension.

In a large number of cases, an underlying cause for hypertension cannot be found. This is described as essential hypertension. Essential hypertension often runs in families.

What is the treatment for hypertension?

If an underlying cause for hypertension is identified, then steps should be taken to evaluate and treat the underlying cause. Patients with underlying diseases often need medications to control their blood pressure; however, the underlying cause must be addressed simultaneously.

In the case of essential hypertension there is no underlying cause of hypertension. In milder cases of essential hypertension, lifestyle modifications such as improved diet and exercise as well as weight loss can result in a return of blood pressures to a normal level. In more severe forms of essential hypertension and in patients who do not respond to lifestyle modifications, medications can be used to lower the blood pressure to normal levels.

What can I do for my child?

Screening blood pressure measurements are a part of all well child check-ups. Parents should take their children for their annual check-ups to ensure proper screening for hypertension.

Given the association of hypertension and obesity, parents should encourage children to develop healthy lifestyle habits, such as eating a well-balanced diet and getting plenty of exercise.

-- Michael J. Campbell, MD, is a pediatric cardiologist at Duke.

-- Dennis Clements, MD, PhD, MPH, is the chief of primary care pediatrics at Duke Children's Hospital.