High Blood Pressure in Children and Adolescents

What is blood pressure?

Blood pressure, measured with a blood pressure cuff around an arm or leg, is the force of the blood pushing against the artery walls.

Two numbers are recorded when measuring blood pressure:

• The higher number, or systolic pressure, refers to the highest pressure inside the artery. It occurs when the heart contracts and pumps blood out to the body.

• The lower number, or diastolic pressure, refers to the lowest pressure inside the artery. It occurs when the heart relaxes and fills with blood.

Each time the heart beats, it pumps blood into the arteries, resulting in the highest blood pressure, the systolic pressure, as the heart contracts, and the lowest blood pressure, the diastolic pressure, as the heart relaxes.

Both the systolic and diastolic pressures are recorded as "mm Hg" (millimeters of mercury).

What is high blood pressure?

High blood pressure means that there is higher than normal pressure inside the arteries either during systole (when the heart contracts and pumps blood through the body), or during diastole (when the heart relaxes and fills with blood.)

• If the pressure is high during the pumping phase (systole), then the first number recorded with a blood pressure reading (the systolic pressure) will be high.

• If the pressure is high during the relaxation phase (diastole), then the second number recorded (the diastolic pressure) will be high.

High blood pressure is also called hypertension.

Is a blood pressure reading always the same?

Blood pressure can be affected by many factors, including, but not limited to, the following:

• The time of day. Blood pressures fluctuate during waking hours, and are lower during sleep.

• Physical activity. Blood pressure is usually higher during and immediately after exercise, and lower at periods of rest.

• Emotional moods and stress. Feelings such as fear, anger, or happiness can affect the blood pressure.

• Age, height, weight, and gender. Each of these can affect blood pressure.

• Other illnesses present or medications you are taking. Other illnesses, including kidney disease or heart disease, affect blood pressure, as can certain medications.

Adolescents may be anxious in a doctor's office, not knowing what may happen. Your doctor is aware that any emotions related to visiting the clinic can affect blood pressure and may give falsely high readings.

Before determining that your child has high blood pressure, a doctor or nurse will take several readings when your child is calm.

When is the blood pressure too high?

Blood pressures vary depending on the age of your child, as well as according to his or her height, weight, and gender. For example, an infant may have a quite normal blood pressure of 80/45, while that value in an adult is considered low. A teenager may have an acceptable blood pressure of 110/70, but that value would be of concern in a toddler. Generally, blood pressure is low in infancy, and rises slowly as children age. Boys' blood pressures are slightly higher than girls', and taller people generally have higher blood pressures than short people.

The National Heart, Lung, and Blood Institute (NHLBI) has prepared a series of age- and gender-specific blood pressure measurement tables for children ages 3 through 17 years, based on percentiles. A range of blood pressure values is given based on how old and how tall your child is. According to the tables, if your adolescent has a blood pressure that is higher than 90% to 95% of other males or females his or her age and height, then he or she may have high blood pressure.

Why is high blood pressure a concern?

High blood pressure, or hypertension, directly increases the risk of coronary heart disease (heart attack) and stroke.

Heart attack and stroke related to high blood pressure are rare in children and adolescents. Yet, high blood pressure can start without any other signs or symptoms and persist undetected for years if not measured. If undiagnosed high blood pressure exists in childhood, then young adults in their 20s can begin to exhibit harmful effects on their heart and blood vessels that can lead to heart attacks and stroke.

What causes high blood pressure?

Blood pressure is classified as "primary," or without a definite cause, and "secondary," related to an illness or behavior.

Risk factors for primary hypertension in adults, and possibly in children and adolescents, include the following:

• High blood cholesterol levels

• Being overweight

• Inactivity

• Smoking

Secondary causes of hypertension in children and adolescents include the following:

• Kidney and heart disease

• Use of prescription medication or illegal recreational drugs (such as cocaine)

Who is at risk for developing high blood pressure?

• Primary hypertension (with an unknown cause) is the most common cause of high blood pressure in adolescents and adults, but is less common in children.

• Many children with high blood pressure also have adult relatives with hypertension, indicating there may be a hereditary aspect to the disease.

• There is a higher incidence of high blood pressure in African-American children after the age of 12 and into adulthood.

• Increased rates of obesity have increased the risk of developing high blood pressure in children. 

How is high blood pressure diagnosed?

Your adolescent's doctor may note an elevated blood pressure reading during a routine office visit. Obtaining calm, resting blood pressures on several different occasions (days, weeks, or months apart) will give better information about whether the blood pressure elevation is consistent or due to fear or stress.

Your adolescent's doctor will take a medical history, including information about your adolescent's diet, exercise level, home and school activities, and possible stressors. A physical exam may also be done.

Additional diagnostic tests, such as urine tests, blood tests, and ultrasound examination of the kidneys, may help your doctor determine the origin of your child's high blood pressure.

Treatment for high blood pressure

Specific treatment for high blood pressure will be determined by your adolescent's doctor based on:

• Your adolescent's age, overall health, and medical history

• Extent of the condition

• Your child's tolerance to specific medications, procedures, or treatments

• Expectations for the course of the condition

• Your opinion or preference

If a secondary cause has been found, such as kidney disease, the disease will be treated. If no cause has been determined, the first treatment approach often involves making appropriate lifestyle changes, including one, or more, of the following:

• Weight reduction

• Increased physical activity

• Healthy diet

These interventions can lower systolic and diastolic blood pressure, improve the strength of the heart, and lower blood cholesterol. These are all important in preventing heart disease as an adult.

High blood pressure usually responds to treatment with these healthy lifestyle modifications. Medications to control high blood pressure are usually not needed in  children and adolescents with the disorder.