Pediatric Annals

Diagnosis and Management of Hypertension in Childhood

Arno R Hohn, MD

Abstract

Blood pressure assessment begins with comparing measurements from a patient with normal values expressed by percentiles. Table 1 provides such a comparison and is based on blood pressures derived from the Second Task Force on Blood Pressure Control in Children (1987). In 1993, a further refinement of the task force norms by Rosner et al added considerations of height (Table 2).

The following are guidelines for normal and high normal blood pressure, and significant and serious hypertension:

* normal blood pressure: systolic and diastolic blood pressures <90th percentile for age and sex,

* high normal blood pressure: average systolic and/or diastolic blood pressure consistently between 90th and 95th percentiles for age and sex,

* significant hypertension: three separate systolic and/ or diastolic blood pressures ≥95th percentile for age and sex, and

* serious hypertension·, rhree separate systolic and/or diastolic blood pressures ≥99th percentile for age and sex.

TECHNIQUE FOR RECORDING BLOOD PRESSURE

If at all possible, blood pressures should be recorded in infancy or early toddlerhood. When evaluating blood pressure in children and adolescents, the mercury sphygmomanometer is the instrument of choice. Oscillometric instruments such as the Dynamap (Critikan Group, Tampa, Florida) are in wide use and provide a reasonable approximation of systolic and mean pressures. Measurements ≥95th percentile on at least three separate occasions are necessary to diagnose hypertension. Using one isolated measurement may mislabel an individual with adverse consequences. Proper cuff size is critical. For practical purposes, the largest cuff that fits the arm leaving the antecubital fossa free for auscultation should be used. It is better to choose a cuff that is slightly too large than one that is too small.

Table

Once-a-day dosage is the preferred initial therapy in most adolescents, and long-acting or sustainedrelease medications are available. Angiotensin-converting enzyme inhibitors and calcium blockers are popular in adults as possible first choices for treating hypertension and are seeing increasing use in pediatrie circles. Classes of antihypertensive medications and specific drugs in each class are listed in Table 4.

Management of Hypertensive Emergencies

When extraordinarily high blood pressure (pressure 1.3 to 1.5 times the 95th percentile) is found with signs of an encephalopathy or heart failure, a true emergency exists and may have disastrous consequences unless efforts to lower blood pressure are begun at once. The child should be hospitalized and an intravenous line placed. If the patient is obtunded, intravenous sodium nitroprusside should be started at a dose of 0.5 pg/kg and titrated as needed to slowly reduce the blood pressure toward the 99th percentile. When the patient becomes responsive, a change to oral medications is advocated. If the patient needing help is conscious when first seen, sublingual nifedipine 0.25 to 0.5 mg/kg every 30 minutes is recommended until a decrease in blood pressure is seen or a maximum dose of 1 mg/kg is reached. At that point, maintenance therapy can be started or other drugs used. Avoidance of hypotension by too rapidly lowering the pressure is important. Following pressure control, a vigorous search for the cause of the hypertension and the hypertensive crisis must be made.

SUMMARY

Blood pressure measurements should be taken at intervals on all children. At the very least, blood pressure measurements should be recorded on school and hospital admission. Once obtained, the pressure should be compared to established normals. If the pressure is repeatedly high, hypertension may be diagnosed and a cause sought. Unfortunately, most hypertension is without known cause. Although hypertension is usually mild in childhood, treatment programs should be initiated using nonpharmacologic measures. If needed, a number of effective antihypertensive medications are available. The step-care approach presented in this…

Blood pressure assessment begins with comparing measurements from a patient with normal values expressed by percentiles. Table 1 provides such a comparison and is based on blood pressures derived from the Second Task Force on Blood Pressure Control in Children (1987). In 1993, a further refinement of the task force norms by Rosner et al added considerations of height (Table 2).

The following are guidelines for normal and high normal blood pressure, and significant and serious hypertension:

* normal blood pressure: systolic and diastolic blood pressures <90th percentile for age and sex,

* high normal blood pressure: average systolic and/or diastolic blood pressure consistently between 90th and 95th percentiles for age and sex,

* significant hypertension: three separate systolic and/ or diastolic blood pressures ≥95th percentile for age and sex, and

* serious hypertension·, rhree separate systolic and/or diastolic blood pressures ≥99th percentile for age and sex.

TECHNIQUE FOR RECORDING BLOOD PRESSURE

If at all possible, blood pressures should be recorded in infancy or early toddlerhood. When evaluating blood pressure in children and adolescents, the mercury sphygmomanometer is the instrument of choice. Oscillometric instruments such as the Dynamap (Critikan Group, Tampa, Florida) are in wide use and provide a reasonable approximation of systolic and mean pressures. Measurements ≥95th percentile on at least three separate occasions are necessary to diagnose hypertension. Using one isolated measurement may mislabel an individual with adverse consequences. Proper cuff size is critical. For practical purposes, the largest cuff that fits the arm leaving the antecubital fossa free for auscultation should be used. It is better to choose a cuff that is slightly too large than one that is too small.

Table

TABLE 1Diagnosis of Hypertension by Age (Modified From Task Force Report)*

TABLE 1

Diagnosis of Hypertension by Age (Modified From Task Force Report)*

Table

TABLE 2Systolic/Diastolic Blood Pressure Levels for Age: Adjusted for Height Percentiles*

TABLE 2

Systolic/Diastolic Blood Pressure Levels for Age: Adjusted for Height Percentiles*

The child should be in a quiet area and have sufficient time to relax. Measurements should be done in the sitting position with the manometer at heart level- The arm (preferably the right) used for the measurement should be recorded in the chart. The cuff pressure should be released at a rate of 2 to 3 mm Hg/second. For diastolic blood pressure, the fifth (disappearance) Korotkoff sound is usually accepted as accurate. A single blood pressure recorded at each visit is all that is necessary. Multiple pressures do not increase predictive value.

CAUSES FOR HYPERTENSION IN CHILDHOOD

Most hypertensive children have no known cause for their disorder and are labeled as having primary or essential hypertension. Blood pressures are usually in the 95th to 99th percentile range in essential hypertension when found in the young. A small number of youths will be found to have serious hypertension, ie, blood pressure >99th percentile. Such people will in all likelihood be found to have a known cause for the disorder labeled secondary hypertension. A number of causes of this type of hypertension are listed in Table 3.

WORK-UP FOR HYPERTENSION

History

Work-up of a young person for hypertension includes a special look for evidence of urinary tract infections or renal disease, or for a past or family history of hypertension. Specific questions should be asked regarding diet, activity, and other habits. Other inquiries include symptoms such as headache, chest pain or dyspnea, muscle weakness, edema, pallor, flushing attacks, or palpitation. Further information sought includes the presence of polydipsia, polyuria, or weight loss; change in hair, body habitus, or menses; previous thyroid or heart disease; and drug use. Additional family history of myocardial infarction, diabetes, or stroke including age at diagnosis is also important. A helpful self-history form is available to expedite this process (Hohn 1994).

Table

TABLE 3Causes of Secondary Hypertension In Childhood

TABLE 3

Causes of Secondary Hypertension In Childhood

Physical Examination

The examination should explote fot evidence of a secondary cause or end-organ damage and include evaluation of:

* pulses in all extremities,

* blood pressure level in both the right arm and thigh,

* body habitus pattern of obesity, ie, "buffalo hump"),

* skin striae/cafe-au-lait spots/neurofibromas,

* careful cardiac/neurologic examination (enlargement/stroke),

* fundi (arteriolar narrowing) and thyroid gland, and

* abdominal masses, flank bruits, and edema.

The evaluation needs to be adjusted according to age, sex, race, and level of hypertension. Thus, a 7year-old black female with no family history of hypertension and a diastolic blood pressure of 105 in all limbs would be a candidate for an aggressive evaluation for secondary causes and, in particular, renal parenchymal disease or renal artery stenosis. In contrast, a 15-year-old black male with a family history of hypertension and a diastolic blood pressure of 92 is not a good candidate for invasive studies to look for a secondary cause.

The following caveats deserve consideration. Severe hypertension suggests renal disease and acute onset of hypertension suggests acute renal disease. Bilaterally enlarged kidneys suggest polycystic disease. Endocrine causes in adolescents are rare and unusual without clinical signs or symptoms.

Laboratory Testing

With an obvious cause for hypertension such as acute renal disease, laboratory testing should be directed at that cause. Otherwise, only a basic set of laboratory tests is recommended. Further testing is reserved for those with serious hypertension (blood pressure ≥99th percentile) in whom secondary hypertension is suspected. Additionally, those whose blood pressure remains significantly elevated (95th to 99th percentile) despite nonpharmacoíogic measures for more than 6 months require further testing.

Basic laboratory tests (limited testing will save time and health-care dollars) include the following:

* hematocrit, hemoglobin, and sedimentation rate,

* urinalysis (with culture in females), and

* blood chemistry panel including blood urea nitrogen, creatinine, glucose, and electrolytes.

The following additional laboratory tests should be conducted if secondary hypertension remains a suspect or if blood pressure remains elevated for more than 6 months:

* echocardiogram: for increased left ventricular wall thickness (considered a rough correlate with time spent hypertensive and is not seen in transient or "white coat hypertension"),

Figure 1. Algorithms for work-up and treatment of childhood hypertension (AV of two measures repeated on next two visits). (Reprinted with permission from Hohn AR. Guidebook for Pediatrie Hypertension. Copyright ©1994, Futura Publishing Co.)

Figure 1. Algorithms for work-up and treatment of childhood hypertension (AV of two measures repeated on next two visits). (Reprinted with permission from Hohn AR. Guidebook for Pediatrie Hypertension. Copyright ©1994, Futura Publishing Co.)

* chest radiograph (insensitive: late finding of cardiomegaly),

* cholesterol and fasting triglycéride, and uric acid (if elevated, this is a marker for hypertension in young people), and

* urine culture (if not previously done).

Tests for Specific Causes of Hypertension

Further diagnostic tests may be indicated in indi' viduals with severe hypertension or with signs or symptoms suggestive of a specific secondary cause. Controversy exists over which of the many available renal or endocrine tests should be ordered and under what circumstances. Consultation with someone knowledgeable about hypertension in young people is helpful to pursue the most cost-effective and safe diagnostic evaluation. Some of the tests include renal and hormonal studies.

Renal Studies. These include radiologie and radioisotope studies, and renal angiography =/- digital subtraction. Timing of angiography depends on age of patient (earlier if younger), sex (earlier if female), and severity of hypertension (earlier if severe).

Hormonal Studies. These include peripheral plasma renin activity, plasma catecholamine, serum aldosterone, and quantitation of urinary aldosterone. Aldosterone and cortisol also may be measured in adrenal venous effluent.

Algorithm for Diagnosis

A scheme has been developed to assist in the diagnosis and management of various levels of hypertension (Figure 1). Important aspects of this flow chart include:

* repeating measurements of blood pressure over several visits,

* taking into account tall individuals (a blood pressure between the 90th and 95th percentile can be normal in an individual taller than the 90th height percentile - the 95th percentiles for blood pressure adjusted for height are listed in Table 2),

* instituting and monitoring a weight reduction program for obese individuals in the 90th to 95th percentile, and

* performing a diagnostic evaluation, implementing nonpharmacological treatment, and possibly instituting drug therapy if the blood pressure remains >95th percentile.

Children Considered to Be at Risk for Hypertension

The following children are considered to be at risk for hypertension:

* those with consistently high normal blood pressure (>90th percentile),

* those with a trend of upward tracking pressures (>75th percentile) or pressures occasionally >95th percentile,

* those who are obese, especially if parents are obese,

* those with hyperlipidemia or a family history of the disorder, especially if with coronary artery disease or stroke,

* those with diabetes mellitus, and

* those with two or more family members with treated hypertension, especially African Americans.

MANAGEMENT

Prevention

Ideally, preventive measures for hypertension should be applied to all children. At the very least, those at risk for developing the disorder in later life should be monitored and treated if blood pressure elevation becomes evident. Until better information becomes available, it is reasonable to consider those with findings listed above as being at risk. They should be counseled about nonpharmacologic treatments to maintain lower blood pressure and monitored periodically.

Treatment Programs

Newly discovered hypertensives often have regression of blood pressure toward normal over time. Thus, unless medical treatment is urgent, nonpharmacologic measures should be begun while slowly proceeding with the basic work-up. Nonresponders with sustained severe hypertension (blood pressure >99th percentile) require full diagnostic evaluation along with drug therapy or treatment of secondary causes. On the other hand, children with only mild residual hypertension (systolic or diastolic blood pressure between 95th and 99th percentiles) should continue on nonpharmacologic measures including periodic blood-pressure determinations.

NonpHarmocologic Measures. These include:

* dietary counseling for obesity, if needed,

* low sodium-high potassium diet with avoidance of foods with high salt content such as steak sauce, pickles, soy sauce, potato chips, pretzels, cola, chocolate, bouillon, frankfurters, and pizza,

* adequate daily amounts of calcium and dietary fiber with fewer saturated fats,

* encouragement of regular physical exercise.

* discontinuance of smoking and avoidance of alcohol excess, medications (save as directed by health-care providers), and drugs, and

* use of methods such as behavior modification, biofeedback, and hypnosis.

Pharmacologie Treatment. Medication(s) are indicated for those who are symptomatic or have dangerously high pressures, ie, >12 mm Hg over 99th percentile diastolic or >25 mm Hg over 99th percentile systolic or have evidence of end-organ damage. If in doubt and the young person is asymptomatic, free of proteinuria, cardiomegaly, or echocardiographic evidence of left ventricular hypertrophy, it may be best to postpone drug treatment.

Figure 2. Individualized stepped approach to the treatment of pediatrie hypertension. (Reprinted with permission from Hohn AR. Guidebook tor Pediatrie Hypertension. Copyright ©1 994, Futura Publishing Co.)

Figure 2. Individualized stepped approach to the treatment of pediatrie hypertension. (Reprinted with permission from Hohn AR. Guidebook tor Pediatrie Hypertension. Copyright ©1 994, Futura Publishing Co.)

Drug therapy should be instituted for those with persistent significant hypertension (blood pressure: 95th to 99th percentile) unresponsive to nonpharmacological measures and having any of the following:

* African-American heritage or strong family history of hypertension,

* other cardiovascular risk factors, and

* evidence of target organ damage.

Care must be exercised in using the label of hypertension in children because if the diagnosis is misapplied, it may lead to exclusion from activities or to future insurance problems.

Debate continues over initial drug treatment programs. A reasonable regimen is the individualized stepped approach outlined in Figure 2. A mono-drug regimen is superimposed on nonpharmacologic therapy as initial treatment. Either a diuretic or beta blocker is used first. They are effective and less costly medications. The more expensive calcium entry blockers or angiotensin-converting enzyme inhibitors are also effective. In studies of adults, both diuretics and beta blockers have not provided the expected degree of protection from coronary artery disease. Both medications have associated problems including: diuretics - hypokalemia, hypercholesterolemia, and hyperglycemia; and beta blockers - elevated triglycérides and lowered high-density lipoprotein cholesterol. Angiotensin-converting enzyme inhibitors and calcium blockers have the potential to control hypertension without these effects. While the long-term side effects and efficacy of these drugs are not yet known, midterm information is promising.

Table

TABLE 4Classes of Antihypertensive Medications

TABLE 4

Classes of Antihypertensive Medications

Once-a-day dosage is the preferred initial therapy in most adolescents, and long-acting or sustainedrelease medications are available. Angiotensin-converting enzyme inhibitors and calcium blockers are popular in adults as possible first choices for treating hypertension and are seeing increasing use in pediatrie circles. Classes of antihypertensive medications and specific drugs in each class are listed in Table 4.

Management of Hypertensive Emergencies

When extraordinarily high blood pressure (pressure 1.3 to 1.5 times the 95th percentile) is found with signs of an encephalopathy or heart failure, a true emergency exists and may have disastrous consequences unless efforts to lower blood pressure are begun at once. The child should be hospitalized and an intravenous line placed. If the patient is obtunded, intravenous sodium nitroprusside should be started at a dose of 0.5 pg/kg and titrated as needed to slowly reduce the blood pressure toward the 99th percentile. When the patient becomes responsive, a change to oral medications is advocated. If the patient needing help is conscious when first seen, sublingual nifedipine 0.25 to 0.5 mg/kg every 30 minutes is recommended until a decrease in blood pressure is seen or a maximum dose of 1 mg/kg is reached. At that point, maintenance therapy can be started or other drugs used. Avoidance of hypotension by too rapidly lowering the pressure is important. Following pressure control, a vigorous search for the cause of the hypertension and the hypertensive crisis must be made.

SUMMARY

Blood pressure measurements should be taken at intervals on all children. At the very least, blood pressure measurements should be recorded on school and hospital admission. Once obtained, the pressure should be compared to established normals. If the pressure is repeatedly high, hypertension may be diagnosed and a cause sought. Unfortunately, most hypertension is without known cause. Although hypertension is usually mild in childhood, treatment programs should be initiated using nonpharmacologic measures. If needed, a number of effective antihypertensive medications are available. The step-care approach presented in this article may be helpful in guiding the pediatrie practitioner in this therapy.

BIBLIOGRAPHY

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Hohn AR. GuiiWxxJi for Pedióme Hypertension. Armonk, NY: Futura Publishing Co; 1994.

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TABLE 1

Diagnosis of Hypertension by Age (Modified From Task Force Report)*

TABLE 2

Systolic/Diastolic Blood Pressure Levels for Age: Adjusted for Height Percentiles*

TABLE 3

Causes of Secondary Hypertension In Childhood

TABLE 4

Classes of Antihypertensive Medications

10.3928/0090-4481-19970201-08

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