High blood pressure, also called hypertension, is a condition most often associated with adults. But kids can have high blood pressure too, even as infants.
High blood pressure in babies is usually caused by prematurity or problems with the kidneys or heart. In many cases when kids and teens have high blood pressure, there are no other health problems but there's a family history of high blood pressure and an unhealthy lifestyle - a bad diet, excess weight, stress, and insufficient physical activity.
An estimated 4.5% of kids have high blood pressure. While the condition is far more common among adults, the rate among kids is on the rise, a trend that researchers link to the increase in childhood obesity.
The only way to know whether your child has high blood pressure is to get it checked regularly. Doctors usually start measuring blood pressure during routine check-ups when a child is about 3 years old.
If it goes untreated, high blood pressure can eventually lead to damage to the heart, brain, kidneys, and eyes. But if it's caught early, monitored, and treated, a child with high blood pressure can lead an active, normal life.
Understanding Blood Pressure
Blood pressure is the pressure the blood exerts against the blood vessel walls as the heart pumps. The pressure increases when the heart contracts and pushes blood into the vessels and lowers when the heart relaxes, but there's always a certain amount of pressure in the arteries.
Blood pressure is driven by two physical forces - the one from the heart as it pumps blood into the arteries and through the circulatory system, and the other from the arteries as they resist this blood flow.
Blood pressure changes from minute to minute and is affected by activity and rest, body temperature, diet, emotional state, posture, and medications.
Long-Term Consequences of High Blood Pressure
When a child has high blood pressure, the heart and arteries have a much heavier workload. The heart must pump harder and the arteries are under greater strain as they carry blood. If high blood pressure continues for a long time, the heart and arteries may no longer work as well as they should. Other organs that are receiving the blood, like the kidneys and brain, may also be affected. Having high blood pressure puts a child at a higher risk for stroke, heart attack, kidney failure, loss of vision, and atherosclerosis (hardening of the arteries).
While a child may not show symptoms of high blood pressure, it still affects the body and puts the child at risk for those long-term health problems. In rare cases, severe hypertension can cause headaches, visual changes, dizziness, nosebleeds, heart palpitations, and nausea. If your child has severe high blood pressure and experiences any of these symptoms, seek medical care immediately.
Measuring Blood Pressure
Doctors typically measure blood pressure with a sphygmomanometer, which has a cuff that's wrapped around the upper arm and pumped up to create pressure. When the cuff is inflated, it compresses a large artery in the arm, stopping the blood flow for a moment. Blood pressure is measured as air is gradually let out of the cuff, which allows blood to flow through the artery again.
The doctor or nurse will also put a stethoscope over an artery to hear the first pulse as the blood flows through - this is the systolic pressure (or the pressure at the peak of each heartbeat). The diastolic pressure (the pressure when the heart is resting between beats) is noted when the sounds disappear. When a blood pressure reading is taken, the higher number represents the systolic pressure and the lower number represents the diastolic pressure. For example: 120/80 (120 over 80) means that the systolic pressure is 120 and the diastolic pressure is 80.
As kids grow, their blood pressure increases from a systolic pressure of about 70-90 in an infant to adult values in a teenager. Among young kids, the "normal" range will depend on the child's gender, age, and height; your child's doctor will be able to compare your child's blood pressure with national norms.
In children, high blood pressure is defined as a blood pressure greater than the 95th percentile for their age, height, and gender (in other words, 95% of kids of the same age, height, and gender will have blood pressure below this number).
It's not unusual for a first blood pressure reading to be high because the child is nervous, so the doctor will likely take three readings - and use an average of the three to determine whether your child has high blood pressure or is at risk for developing the condition.
Causes of High Blood Pressure
The causes of high blood pressure differ, depending on the age of the child. The younger the child, the more likely the high blood pressure is linked to some other illness.
High blood pressure among infants most commonly occurs in those born prematurely. Some newborns have high blood pressure because of problems with the kidneys, lungs, heart, or vascular system. Often, these problems are due to bronchopulmonary dysplasia, an immaturity of the lungs in premature babies, or problems like coarctation of the aorta, a narrowing of part of the major blood vessel that transports blood away from the heart.
Among school-age kids and teens, hypertension is usually linked to excess weight. In some cases it's due to a problem with the kidneys, although other conditions - like abnormalities in the blood vessels and hormonal disorders - can also be responsible. Some medications (such as steroids or oral contraceptives) can lead to high blood pressure, as can overconsumption of alcohol and illegal drugs.
Diagnosing High Blood Pressure
Because high blood pressure usually doesn't produce any symptoms, diagnosing the condition in kids can be tricky. The only reliable way to find out if your child has high blood pressure is to have it regularly measured at routine check-ups. So it's important not to miss those appointments, particularly if your child is obese or if there's a family history of high blood pressure.
There's also a new test called ambulatory blood pressure monitoring in which a child wears a blood pressure cuff all day. Some consider it more accurate than blood pressure tests in the doctor's office because the child is less likely to be affected by any stress from visiting the doctor.
Treating High Blood Pressure
If an underlying illness is causing hypertension, treating that illness may be enough to get the blood pressure back to normal levels. If there's no underlying illness, your child's doctor may recommend weight loss, increased intake of fruits and vegetables, decreased salt intake, increased exercise, and even relaxation techniques. Kids with hypertension should also quit or never start smoking, which can worsen the long-term associated heart problems.
Most doctors prefer not to prescribe medication for children with mild hypertension. However, in cases in which lifestyle changes do not improve the condition, medications may be necessary.
Exercise and participation in organized sports is encouraged for all patients whose hypertension is not severe or is well-controlled. In fact, staying fit is the key to both weight and blood pressure control. If your child is overweight, an ongoing weight-loss program monitored by your child's doctor and a minimum of 30 minutes of aerobic exercise every day may be recommended. Kids who have severe hypertension should not, however, participate in weight- and power-lifting, bodybuilding, or strength training until their blood pressure is under control and a doctor OKs it.
Although severe hypertension is rare in kids, even mild to moderate hypertension over time can cause damage to the heart, kidneys, and blood vessels. Identifying and treating high blood pressure in children will help prevent this damage before it occurs.
Reviewed by: Samuel S. Gidding, MD
Date reviewed: October 2005
Originally reviewed by: Elana Pearl Ben-Joseph, MD
