HIGH BLOOD PRESSURE OVERVIEW

Blood pressure (BP) refers to the pressure that blood applies to the inner walls of blood vessels. High blood pressure is also called hypertension. Although hypertension is more common in adults, it often develops during childhood and adolescence, and can increase the risk of early heart disease and stroke during adulthood. Fortunately, high blood pressure can be treated.

WHAT IS BLOOD PRESSURE?

An individual's blood pressure is defined by two measurements:

• Systolic pressure is the pressure in the arteries produced when the heart contracts (at the time of a heart beat)
• Diastolic pressure refers the pressure in the arteries during relaxation of the heart between heart beats.

Blood pressure is reported as the systolic pressure over diastolic pressure (eg, 120/70 or 120 over 70). Both values are of equal importance. The diagnosis of high blood pressure can be based upon either measurement as they are of equal importance.

Normal versus high blood pressure — In children, the normal range for blood pressure is determined by the child's gender, age, and height. The normal range is expressed as a percentile, similar to charts used to track childrens' growth.

As an example, if a child's BP is in the 60th percentile, this means that 60 percent of children who are that age, gender, and height have a lower blood pressure.

A child's blood pressure percentile can be calculated here for boys (calculator 1) or here for girls (calculator 2).

BP is separated into three categories based upon the child's BP percentile:

Normal BP — Both systolic and diastolic BP <90th percentile.

Prehypertension — Systolic and/or diastolic BP ≥90th percentile but <95th percentile or if BP exceeds 120/80 mmHg (even if <90th percentile for age, gender, and height).

Hypertension — Hypertension (HTN) is defined as either systolic and/or diastolic BP ≥95th percentile measured on three or more separate occasions. The degree of hypertension is further delineated by the two following stages.

• Stage 1 hypertension — Systolic and/or diastolic BP between the 95th percentile and 5 mmHg above the 99th percentile.
• Stage 2 hypertension — Systolic and/or diastolic BP ≥99th percentile plus 5 mmHg.

HIGH BLOOD PRESSURE SYMPTOMS

High blood pressure does not usually cause any symptoms.

BLOOD PRESSURE MEASUREMENT

Expert groups recommend that all children over age 3 years have their blood pressure measured during routine office visits once per year. Blood pressure measurements may be recommended at an earlier age in children who have kidney or heart disease.

It is important for the healthcare provider to measure the blood pressure accurately, using the correct equipment and technique. Parents should be aware of the following:

• The BP should be measured after the child has been sitting in a quiet environment for a few minutes. The child should be seated with his/her back and feet in a supported position. In infants, BP is measured while the child lies on his/her back. It may be necessary to measure the BP a few times (several minutes apart) to get the most accurate reading.
• The BP should not be measured if the child is crying or unable to cooperate.
• An appropriate-size cuff should be used. A cuff that is too small can overestimate the BP.
• BP should be measured in the right arm.
• Stimulants such as cigarettes and caffeine should be avoided for several hours before the blood pressure is measured.

HIGH BLOOD PRESSURE DIAGNOSIS

The diagnosis of hypertension is made when the BP is at or greater than the 95th percentile on three separate measurements, which are separated by days or weeks.

When HTN is diagnosed, testing is recommended to help determine the cause of the HTN. The evaluation generally includes a medical history and physical examination, measurement of blood pressure in the arms and legs, laboratory tests, and a ultrasound of the heart and kidneys.

TYPES OF HIGH BLOOD PRESSURE

If a child is diagnosed with high blood pressure, the next step is to determine if a cause of the hypertension can be determined. Patients in whom no cause can be identified have primary or essential HTN and those with an identifiable cause have secondary HTN.

Primary HTN — Primary HTN, also called essential HTN, has no identifiable cause. It is the most common cause of HTN in older children.

Primary HTN is more likely in children who:

• Have completed puberty
• Have a family history of HTN
• Are overweight or obese
• Have only mild hypertension (BP at or just above the 95th percentile)

Secondary HTN — Secondary HTN has a known cause. The most common causes of secondary HTN include kidney disease, endocrine disorders, heart disease, and some medications.

Secondary HTN is more likely in children who:

• Are younger than 10 years of age
• Have a sudden increase in blood pressure when the BP has previously been normal
• Have severe HTN, defined as stage 2 HTN (BP >5 mmHg above the 99th percentile. (See 'Hypertension' above.)

"White coat" HTN — "White coat" hypertension is the name given to high blood pressure caused by anxiety when blood pressure is measured in clinic or office. Measuring the blood pressure several times during the office visit (to minimize anxiety) and/or measuring the BP outside the physician's office can help to determine if a person has white coat HTN or is truly hypertensive.

HIGH BLOOD PRESSURE TREATMENT

Treatment of high blood pressure in children is discussed in detail in a separate topic review. (See "Patient information: High blood pressure treatment in children".)

WHERE TO GET MORE INFORMATION

Your child's healthcare provider is the best source of information for questions and concerns related to your child's medical problem.

This article will be updated as needed every four months on our web site (www.uptodate.com/patients).

Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.

Patient level information

Patient information: High blood pressure treatment in children

Professional level information

Ambulatory blood pressure monitoring in children
Definition and diagnosis of hypertension in children and adolescents
Epidemiology, risk factors, and etiology of hypertension in children and adolescents
Evaluation of hypertension in children and adolescents
Treatment of hypertension in children and adolescents

The following organizations also provide reliable health information.

• National Library of Medicine

      (www.nlm.nih.gov/medlineplus/healthtopics.html)

• The Nemours Foundation

      (http://kidshealth.org/parent/medical/heart/hypertension.html)

• The National Kidney Foundation

      (www.kidney.org/atoz/atozItem.cfm?id=164)

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