Even very young children can have high blood pressure. Medical problems such as heart or kidney disease are often the cause of high blood pressure in children younger than 10 years, explains MayoClinic.com. Blood pressure normally rises somewhat throughout childhood, but if your child has one or more risk factors for high blood pressure, his pediatrician may recommend more frequent blood pressure checks.

Blood Pressure Tables

Blood pressure tables for children and adolescents list the 50th, 90th, 95th and 99th percentiles for systolic and diastolic blood pressure based on a child’s height, age and sex. The 50th percentile gives doctors the blood pressure level at the midpoint of the normal range. Children who fall within the 95th percentile have a blood pressure level indicating hypertension and require further medical evaluation, according to the National Heart, Lung and Blood Institute.

Interpreting Blood Pressure Tables

If systolic and diastolic blood pressure is lower than the 90th percentile, the child’s blood pressure is normal and should be checked again in one year. If either the systolic or diastolic blood pressure reading is greater than the 90th percentile, the child’s blood pressure should be retaken during the same doctor visit. It’s possible that your child could be prehypertensive and should have her blood pressure rechecked in six months if the systolic or diastolic blood pressure reading is greater than the 90th percentile, but less than the 95th percentile. Your child’s doctor may place him on a weight management program if weight is a problem.

A child whose blood pressure falls between the 95th and 99th percentile and remains at this level when it is rechecked the following week should be evaluated to determine if treatment is necessary. Treatment for children who are classified as hypertensive as a result of systolic and/or diastolic blood pressure greater than the 99th percentile should begin immediately, recommends the National Heart, Lung and Blood Institute.

Taking a Child’s Blood Pressure

Routine blood pressure measurement for children should begin at age three as recommended by the American Heart Association. Seat the child and take the blood pressure reading in the right arm. Auscultation is the gold standard for blood pressure measurement, although automated blood pressure devices can provide reasonably accurate readings. The auscultation method uses a stethoscope and manual sphygmomanometer — consisting of an inflatable cuff, mercury manometer and inflation bulb — to measure blood pressure. Repeat the measurement using a sphygmomanometer if an automated blood pressure device shows a high blood pressure. Don’t take your child’s blood pressure if she is crying as this can raise his reading.

Effects of High Blood Pressure

High blood pressure, or hypertension, is not something that occurs only in adults. About 5 percent of children have high blood pressure, although they might not show any symptoms, as reported in the 2007 edition of the Harvard Medical School “Family Health Guide.” Taking a child’s blood pressure as part of routine medical exams is critical because if left untreated, high blood pressure can cause serious health problems later on.

Normal Range

Systolic blood pressure is the top number of blood pressure readings and measures the pressure in the arteries when the heart beats. Health care providers are usually more concerned about this top number because a higher than normal reading is a major risk factor for cardiovascular disease later in life. Measured in milligrams of mercury, a normal blood pressure range for an adult over age 20 is less than 120 over 80; a healthy blood pressure range for a child should be 10 to 20 mm less for both systolic and diastolic readings, according to Dr. Roger Blumenthal, professor of medicine in the cardiology division at Johns Hopkins University School of Medicine. A very young child’s systolic blood pressure should be less than 100, and once a child becomes an adolescent, systolic blood pressure should be less than 110.

Causes of High Blood Pressure in Children

Boys tend to have higher normal blood pressure readings than girls the same age, and taller children have higher normal readings than children of shorter stature. If a child is identified as having high blood pressure, the clinician will conduct a more comprehensive evaluation to determine the cause. In cases where there is no apparent cause, primary hypertension is the diagnosis; this is the most common explanation of high blood pressure in older children. Risk factors include puberty, overweight and a family history of hypertension. Secondary hypertension usually occurs in children under age 10 and is caused by heart or kidney disease, endocrine disorders or certain medications.