American Association of Kidney Patients

Tykster, a 14-year old 8th grader was the star point guard of his school basketball team and dreamt of playing college basketball at his regional university, one of the winningest programs in college sports history. Before his sophomore year, he underwent his regular school physical exam, and his blood pressure was found to be elevated. His family doctor confirmed the blood pressure increase, performed preliminary tests which did not help explain this finding, and accordingly referred Tykster to a children’s kidney specialist (pediatric nephrologist) for further evaluation and management.

“High blood pressure in a child ? No way !!” Many people may think of high blood pressure, also called hypertension, as an “adult” condition, and they have a point: About 25 percent of all adults have high blood pressure. Most adults with high blood pressure have essential hypertension, meaning that there is no completely specific or treatable cause for the high blood pressure. They, therefore, need to attempt “therapeutic lifestyle changes” (TLCs), typically including dietary adjustments and increased amounts of exercise (see below), aimed to normalize body weight and blood pressure. Oftentimes, these changes are not successful enough, and blood pressure medication needs to be taken regularly to completely control essential hypertension.

In contrast, high blood pressure is indeed found less often in children: Only approximately 1 percent of the general pediatric population is hypertensive, but there are concerning indications that this percentage is rising (see below). The causes of pediatric hypertension are also more complex than in adults because young (i.e. non-teenage) children can have a variety of very specific reasons for their high blood pressure. While the search for these specific causes can be difficult and exhausting, finding such an identifiable cause may offer an opportunity to correct or remove it. Consequently, the need for long-term antihypertensive drug therapy is not as universal as it is in adults with essential hypertension. Essential hypertension, however, is the most common cause of high blood pressure in teenagers. In fact, as the American population, including the teenagers, has become more and more obese, essential hypertension has become significantly more common in this age group, largely explaining the ongoing rise in the frequency of high blood pressure in children mentioned above.

Tykster’s pediatric nephrologist took his history and examined him. At the end of the exam, the doctor asked him if he had ever had his blood pressure taken in his leg. “In my leg? No, sir,.” Tykster replied. The doctor wheeled in the automated blood pressure recorder, used it to compare Tykster’s arm and leg blood pressures, and found that the readings in his legs were substantially lower than in his arms. In fact, Tykster also had much weaker pulses in his legs and feet than in his wrists. The doctor explained that this worried him because Tykster may have a narrowing of a large blood vessel coming out of his heart and supplying blood all over his body, with branches to the head and arms coming off before the narrowing and thus receiving excessive amounts of blood while the blood flow beyond the narrowing, i.e. to the legs, was decreased and thus associated with weak pulses and low blood pressure there. This concern required further evaluation by a specialist for heart and large blood vessel disease in children, a pediatric cardiologist, and Tykster was quickly referred to one.

Specific, identifiable and thus possibly correctable causes for hypertension can be found in the majority of affected children between ages 1 and 10 years. Two significant subgroups of these causes involve either the kidneys or the aorta, a large blood vessel close to heart. Accordingly, many hypertensive children are referred to specialists for kidney or heart diseases in children, i.e. pediatric nephrologists or cardiologists.

Hypertension can be related to kidney disease in several ways. Long-standing, poorly controlled essential hypertension alone can substantially damage previously healthy kidneys.

In children, uncontrolled hypertension does not have enough time to lead to ESRD, but it may speed up the worsening of kidney function caused by other kidney diseases, such as chronic inflammation of the kidney filters (chronic glomerulonephritis in IgA nephropathy, focal-segmental glomerulosclerosis or other conditions) or kidney damage associated with urinary reflux (reflux nephropathy). Moreover, these diseases, by causing inflammation and scarring of the kidney tissue as well as fluid build-up when kidney damage is more advanced, can cause hypertension themselves.

When Tykster saw the pediatric cardiologist, an ultrasound of the heart - called echocardiogram - and the great blood vessels nearby was performed, and the suspected narrowing of the vessel supplying blood to the body, the aorta, was demonstrated, establishing the diagnosis of coarctation of the aorta as the cause for Tykster’s hypertension (see figure below). Several treatment options were discussed with Tykster and his family, including both a surgical repair as well as stenting of the narrowing during a catheterization procedure. Tykster and his family chose the latter which was performed soon thereafter without complications (see pictures below). Tykster’s blood pressures consequently improved to where it is now lower in his arms and more normal in his legs.

Figure 2: Contrast dye images of Tykster’s coarctation before (left) and after (right) treatment (A = aorta, courtesy of Dr. Robert Beekman, Division of Cardiology, Cincinnati Children’s Hospital).

Tykster’s example shows that high blood pressure can indeed be found in children, although much less often than in adults, and that it can fairly commonly have specific, correctable causes as opposed to the high frequency of essential hypertension in adults. Indeed, while Tykster’s age would have suggested essential hypertension as the cause of his high blood pressure, a thorough evaluation uncovered coarctation of the aorta as the real reason and lead to a targeted corrective intervention. While Tykster should be able to live a rather normal life and especially pursue his athletic ambitions, he will need to be followed at regular intervals as coarctations can recur and, especially if not diagnosed early in childhood, require some antihypertensive drug treatment even after corrective intervention.

Hypertension is not just for adults anymore. According to the guidelines by the American Academy of Pediatrics (see references at the end of this article), screening for children should be part of routine physical exams beginning at 3 years of age, especially because obesity is reaching epidemic proportions in our country, accompanied be a rise in the frequency of hypertension among kids. While obesity is clearly not the only reason for hypertension in children, it is the most common cause in the teenage population.

Normal blood pressure is based on height, age and gender. It is different for boys and girls. Hypertension in children is defined as properly measured elevated blood pressure on three separate occasions. A simplified summary of upper normal limits (95th percentiles) for first (systolic) and second (diastolic) blood pressure values (i.e. 105/70 means 105 is the systolic and 70 the diastolic value) is given in the table below (from A. R. Sinaiko: “Hypertension in Children”, New England Journal of Medicine, 1996). Height percentiles indicate how a child’s height compares to that of other children, i.e. a child at the 50th height percentile is shorter than half of all other children of her/his gender and age and taller than the other half.
chart of 95th percentile of blood pressure in boys

chart of 95th percentile of blood pressure in boys

In diagnosing hypertension, it is important that the proper size cuff be used for blood pressure measurement. Proper size cuff is determined by measuring mid-arm circumference which is the middle portion of the upper arm. This measurement then corresponds with various cuff sizes. These sizes begin with cuffs for infants all the way up to and including a very large cuff such as the thigh size for obese teens.

As many factors can influence blood pressure, it is important to make circumstances and situations for accurate measurement as ideal as possible. Your child should sit in a chair with her/his back supported and feet on the ground for at least five minutes before measurement begins. It is appropriate to palpate (feel) the radial (wrist) pulse while inflating the cuff, waiting for the pulse to disappear and then reappear while deflating the cuff to determine an estimate of where your child’s blood pressure is. This technique prevents overinflation of the blood pressure cuff which can cause discomfort and, thus, falsely elevate blood pressure. Along the same lines, it is important that your child did not exercise vigorously, smoke, or feel upset prior to having her/his blood pressure measured.

There is also a real diagnosis known as white coat hypertension. This is a rise in blood pressure caused by “white coats” or people and places associated with the medical profession. Today, we use ambulatory blood pressure monitors to rule out white coat hypertension. This is a cuff that is applied to the non-dominant arm and connects to a little box that can be worn on the belt or carried like a purse over the shoulder. This device collects data (blood pressure) for a 24 hour period wherever your child is – at school, at home or elsewhere, even while she/he is asleep. It records the blood pressure every twenty minutes during the day and every thirty minutes at night beginning at midnight. Once the monitor is returned, the blood pressure measurements are downloaded and analyzed to establish if blood pressure elevation occurs away from the clinical setting and or during sleep. White coat hypertension is not considered a disease and only requires regular follow-up, as some individuals with this diagnosis may develop true hypertension in the future.

If your child is suspected to have or diagnosed with hypertension, her/his doctor may order a number of diagnostic tests to look for specific causes of the high blood pressure or refer her/him to a specialist for further evaluation. One helpful test for children with high blood pressure is a renal ultrasound, i.e. an ultrasound of the kidneys. This is a non-invasive procedure where an ultrasound technician puts a jelly-like substance on the belly and back before moving an ultrasound wand around on their surface bringing images of the kidneys to a screen. A renal ultrasound is helpful to determine whether the cause of hypertension might be related to a kidney problem.

Another helpful test is an echocardiogram, i.e. an ultrasound of the heart. With this test, the jelly-like substance is applied to the chest, and the technician moves the wand around on the chest, bringing images of the heart and adjacent large vessels to a screen. This test is helpful in determining if the high blood pressure has been a long standing problem because it will reveal a condition known as left ventricular hypertrophy (LVH). Your heart is a muscle. If you or your child’s blood pressure is high, it creates increased resistance in the vessels through which the heart pumps blood and thus increased work demands on the heart. The heart muscle responds to this increased workload by increasing its size, essentially not different from any other muscle in your body - if you are lifting weights, for example, the muscles in your arms increase in size. However, if the heart muscle grows too much, it can compromise its own blood supply, and LVH, therefore, is an ominous finding. An echocardiogram is also a helpful screening tool for coarctation of the aorta (as found in Tykster’s case above) as the aorta is one of the large blood vessels close to the heart that are seen during an echocardiogram.

While hypertension in children can have specific and even correctable causes, it can also require long-term treatment. The most basic and first step along these lines are therapeutic lifestyle changes (TLCs). A healthy diet and regular physical activity are important for people of all ages no matter what their health status, but a healthy lifestyle is especially important in the prevention and treatment of hypertension in children and teens. Healthy eating and regular physical activity help kids achieve or maintain a healthy weight, which can help reduce the risk of hypertension and heart disease.

According to the Center for Disease Control (CDC), 16 percent of children and adolescents ages 6-19 years were overweight between 1999-2002. This number continues to grow at an alarming rate. Overweight is defined as a body mass index (BMI) greater than the 95^th percentile on the CDC growth chart. The BMI is determined based on your child’s height and weight as body weight in kilograms divided by the squared height in meters (kg/m²). Ask your child’s doctor to calculate and plot your child’s BMI at his/her next visit, as being overweight increases your child’s risk of many diseases, not just hypertension, type 2 diabetes, high cholesterol, stroke, heart disease, sleep apnea, some cancers, and problems with joints and bones. Type 2 diabetes used to be considered an “adult” disease, but now it is being diagnosed in children and teens as young as 10 years old.

The best way to help your child is to get the entire family involved in developing healthy eating and exercise habits. The National Institutes of Health have published the DASH (Dietary Approaches to Stop Hypertension) Eating Plan (http://www.nhlbi.nih.gov/health/public/heart/hbp/dash/index.htm). It has been shown to lower blood pressure in adults and is being recommended to treat high blood pressure in kids. This eating plan consists of 4-5 servings of fruits, 4-5 servings of vegetables, and 3 servings of low-fat dairy products daily.

Most kids aren’t eating enough fruits and vegetables. One serving is only ½ cup of cut up fruit or vegetables, or 1 medium piece of fruit. Start off slowly and gradually increase the amount of produce in your family’s diet. Add 1 extra serving of fruit every day, maybe for a snack or eat fruit with dinner. Try having two different vegetables with dinner. Salsa with low-fat, low-sodium chips or on a whole wheat flour tortilla with low-fat cheese is a fun way to add a serving of vegetables. Involve children in food preparation and shopping. Let them choose new fruits and vegetables to try from the grocery store or local farmer’s market.

Limiting processed foods can help lower sodium in your diet. Too much sodium may increase blood pressure. Some frozen meals, canned soups and canned vegetables, as well as pickles, soy sauce, and processed meats such as hot dogs, ham, and sausage tend to be high in sodium. Look for products that say “no added salt” or reduced sodium if you are buying canned or packaged foods. Use herbs and spices to season pasta and rice instead of using the pre-packaged mixes. Avoid adding salt in cooking and fill the salt shaker with dried herbs or a salt-free flavoring. Foods can still be flavorful without salt; try red pepper flakes and garlic powder to start..

Eating out can make eating healthy difficult. Most fast food menu items are high in sodium and fat. However, there are healthy options available. If you can, review the menu before arriving at the restaurant and select a healthy option with your child before you arrive. Many fast food chains offer fruits or vegetables instead of fries.

Make it easy for your child to eat healthy by keeping only healthy snacks at home. Some examples include fresh fruits and vegetables, whole grain cereal, low-fat yogurt, and unsalted nuts. Keep fresh fruit on the counter and cut up vegetables in an easy to spot part of the refrigerator. Get rid of any junk food so the kids aren’t tempted.

Physical activity is also an important part of a heart healthy lifestyle. Even if your child does not enjoy sports, find other ways to be active. Ask them what they like to do to get their body moving. Walking is a good way for the family to be active together. Plan family walks or hikes around the neighborhood or park, have a dance contest or let your child dance to music alone. Keep balls, jump ropes, and other sports equipment available at home. Limit television, video games and computer time to no more than two hours per day.

In summary, now is the time to help your child be healthy - make it fun and remember that these changes will work best if everyone in the family participates! More fruits and vegetables and more active play will benefit the entire family.

Unfortunately, not all children achieve blood pressure normalization just with TLCs or because they have entirely correctable causes for their hypertension. For these individuals, long-term drug treatment is required to prevent the dismal effects of long-standing hypertension such as stroke, heart disease or kidney damage. Several different groups of medications are available, although a number of these drugs still have not been tested specifically in children. Accordingly, family practitioners or general pediatricians at times prefer to ask pediatric nephrologists or cardiologists to become involved in the drug treatment of their young patients’ high blood pressure, even if it may be caused by essential hypertension.

The drug groups typically used include fluid pills (diuretics), drugs that relax the blood vessels by changing how the muscle tissue in the vessel wall handles calcium (calcium antagonists), drugs that suppress the formation or block the action of hormones that raise blood pressure (angiotensin converting enzyme blockers or angiotensin receptor blockers), drugs that down-modulate the “stress” response part of the nervous system (beta-blockers), and sometimes other medications. Usually, one agent is prescribed and its dose adjusted until adequate blood pressure control is achieved, but a combination of agents can sometimes also be necessary. While the initial choice of drug depends largely on the patient’s individual diagnosis and overall medical status, diuretics are commonly prescribed for teenagers with essential hypertension. Other factors guiding drug selection are drug availability in liquid form for younger patients and ease of administration, i.e. only once or twice daily. Lastly, there is blood pressure medication available as a skin patch that only needs to be replaced once a week for individuals who may have a lot of trouble remembering to take their daily pills.

To summarize, high blood pressure in children has become a growing problem. While a number of children have high blood pressure because they have specific conditions such as kidney disease, a substantial percentage of hypertensive children, especially teenagers, are otherwise healthy and thus have essential hypertension. Essential hypertension in children, in turn, is often associated with obesity and can be controlled and even corrected by TLCs as outlined above. These TLCs not only help children be healthier and thus more self-confident, but - if instituted by the whole family - improve the well-being of all generations in the family unit. Moreover, they are key contributions to our battle against the obesity and inactivity epidemic affecting our society. For more information on this topic, please consult these resources:

All authors work at Cincinnati Children’s Hospital. Janis Kartal is a nurse in the pediatric nephrology and hypertension division, and Katie Dart is a dietician. Both regularly see patients in a clinic specially held for children with high blood pressure. Jens Goebel is a pediatric nephrologist.

This article originally appeared in the February 2008 edition of Kidney Beginnings: The Magazine.