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Hypertension in Children: Diagnosis and Treatment


Over the past decade, there has been increasing interest in childhood hypertension and greater recognition that adult cardiovascular disease has its origins in childhood. Fueling this interest has been the childhood obesity epidemic, which has led to an increase in the prevalence of hypertension and its consequences in the young. This chapter will discuss some of the recent trends in pediatric hypertension, with a focus on the importance of correctly identifying and treating hypertensive children and adolescents. Important differences in clinical practice guidelines for hypertension in adults and children will be highlighted when appropriate. Selected special topics in childhood hypertension, including hypertension in children with chronic kidney disease and management of acute severe hypertension will be briefly reviewed.

Epidemiology of Hypertension in Children and Adolescents

Recent screening studies and population-based surveys have provided updated information of the prevalence of elevated blood pressure (BP) in the young. When Fourth Report BP cut-points are used and data from three screening visits included, there is a consistent prevalence of approximately 3% to 4% for hypertension and 7% to 15% for prehypertension (see following section for definitions).

Data from national surveys such as the National Health and Examination Survey in the United States have demonstrated an increase in the prevalence of both prehypertension and hypertension over recent years in the pediatric age group. Although there is some disagreement in the literature, most experts attribute this increase to the significantly higher prevalence of childhood obesity that has developed over the past several decades. Indeed a recent examination of BP and lipid levels in United States children clearly showed that the prevalence of elevated BP was greater in overweight and obese children than in the population as a whole. This has also been shown in school-based screening studies conducted in both the United States and abroad. Potential mechanisms for this phenomenon are beyond the scope of this chapter but have recently been reviewed. As the prevalence of childhood obesity appears to have leveled off in the most recent data from the Centers for Disease Control and Prevention, there is hope that the prevalence of childhood hypertension may stabilize, at least in the United States.

Definition of Hypertension in Childhood

Defining hypertension in children is challenging because there are no outcome data to support a particular level, such as the widely used 140/90 for adults ( Table 17.1 ). Additionally, BP increases with age and linear growth and thus the absolute value that defines an elevated BP will differ greatly as an infant grows into a young adult. As a result, the definition is based on the statistical analysis of normative data obtained from readings on more than 60,000 U.S. children and adolescents. From this analysis tables have been generated that display the 50th, 90th, 95th, and 99th percentiles based on age, gender, and height percentile (see Tables 17.2 and 17.3 ). Prehypertension and hypertension are defined as noted in Table 17.1 . The diagnosis of hypertension is made when the average BP is greater than or equal to the 95th percentile on 3 or more occasions. Use of height percentiles may be problematic for some providers; therefore simplified tables that define the BP percentiles based on absolute height rather than height percentile have been created and are available through the International Pediatric Hypertension Association ( http://d706084.u55.profitability.net/wp-core/wp-content/uploads/BPLimitsChart0112.pdf ). Categorization of elevated BPs into stages 1 and 2 is explained in Table 17.1 , which compares the pediatric definitions to the corresponding definitions for stages of hypertension in adults.

TABLE 17.1
Classification of Childhood Blood Pressure Compared With Adult Classification
Blood Pressure Classification Children and Adolescents Under 18 Years of Age a Adults 18 Years of Ageor Older b
Normal SBP and DBP <90th percentile SBP <120 mm Hg and DBP <80 mm Hg
Prehypertension SBP or DBP 90-95th percentile; or if BP is >120/80 even if
<90th percentile		 SBP 120-139 mm Hg or DBP 80-89 mm Hg
Stage 1 hypertension SBP or DBP ≥95th to 99th percentile plus 5 mm Hg SBP 140-159 mm Hg or DBP 90-99 mm Hg
Stage 2 hypertension SBP or DBP >99th percentile
plus 5 mm Hg		 SBP ≥160 mm Hg or DBP ≥100 mm Hg
BP, Blood pressure; DBP, diastolic blood pressure; SBP, systolic blood pressure ; SNP, systolic blood pressure.

a Adapted from National High Blood Pressure Education Program Working Group on High Blood Pressure in Children and Adolescents. The fourth report on the diagnosis, evaluation, and treatment of high blood pressure in children and adolescents. National Heart, Lung, and Blood Institute, Bethesda, MD 2005; National Institute of Health publication 05:5267.

b Adapted from Chobanian AV, Bakris GL, Black HR, et al. The seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: the JNC 7 report. JAMA . 2003;289:2560-2572.

TABLE 17.2
Blood Pressure Levels for Boys by Age and Height Percentile
(Adapted from National High Blood Pressure Education Program Working Group on High Blood Pressure in Children and Adolescents. The fourth report on the diagnosis, evaluation, and treatment of high blood pressure in children and adolescents. National Heart, Lung, and Blood Institute, Bethesda, MD 2005; National Institute of Health publication 05:5267).
Blood Pressure Systolic Blood Pressure (mm Hg) Diastolic Blood Pressure (mm Hg)
Percentile ← Percentile of Height → ← Percentile of Height →
Age (Years) ↓ 5 10 25 50 75 90 95 5 10 25 50 75 90 95
1 50 80 81 83 85 87 88 89 34 35 36 37 38 39 39
90 94 95 97 99 100 102 103 49 50 51 52 53 53 54
95 98 99 101 103 104 106 106 54 54 55 56 57 58 58
99 105 106 108 110 112 113 114 61 62 63 64 65 66 66
2 50 84 85 87 88 90 92 92 39 40 41 42 43 44 44
90 97 99 100 102 104 105 106 54 55 56 57 58 58 59
95 101 102 104 106 108 109 110 59 59 60 61 62 63 63
99 109 110 111 113 115 117 117 66 67 68 69 70 71 71
3 50 86 87 89 91 93 94 95 44 44 45 46 47 48 48
90 100 101 103 105 107 108 109 59 59 60 61 62 63 63
95 104 105 107 109 110 112 113 63 63 64 65 66 67 67
99 111 112 114 116 118 119 120 71 71 72 73 74 75 75
4 50 88 89 91 93 95 96 97 47 48 49 50 51 51 52
90 102 103 105 107 109 110 111 62 63 64 65 66 66 67
95 106 107 109 111 112 114 115 66 67 68 69 70 71 71
99 113 114 116 118 120 121 122 74 75 76 77 78 78 79
5 50 90 91 93 95 96 98 98 50 51 52 53 54 55 55
90 104 105 106 108 110 111 112 65 66 67 68 69 69 70
95 108 109 110 112 114 115 116 69 70 71 72 73 74 74
99 115 116 118 120 121 123 123 77 78 79 80 81 81 82
6 50 91 92 94 96 98 99 100 53 53 54 55 56 57 57
90 105 106 108 110 111 113 113 68 68 69 70 71 72 72
95 109 110 112 114 115 117 117 72 72 73 74 75 76 76
99 116 117 119 121 123 124 125 80 80 81 82 83 84 84
7 50 92 94 95 97 99 100 101 55 55 56 57 58 59 59
90 106 107 109 111 113 114 115 70 70 71 72 73 74 74
95 110 111 113 115 117 118 119 74 74 75 76 77 78 78
99 117 118 120 122 124 125 126 82 82 83 84 85 86 86
8 50 94 95 97 99 100 102 102 56 57 58 59 60 60 61
90 107 109 110 112 114 115 116 71 72 72 73 74 75 76
95 111 112 114 116 118 119 120 75 76 77 78 79 79 80
99 119 120 122 123 125 127 127 83 84 85 86 87 87 88
9 50 95 96 98 100 102 103 104 57 58 59 60 61 61 62
90 109 110 112 114 115 117 118 72 73 74 75 76 76 77
95 113 114 116 118 119 121 121 76 77 78 79 80 81 81
99 120 121 123 125 127 128 129 84 85 86 87 88 88 89
10 50 97 98 100 102 103 105 106 58 59 60 61 61 62 63
90 111 112 114 115 117 119 119 73 73 74 75 76 77 78
95 115 116 117 119 121 122 123 77 78 79 80 81 81 82
99 122 123 125 127 128 130 130 85 86 86 88 88 89 90
11 50 99 100 102 104 105 107 107 59 59 60 61 62 63 63
90 113 114 115 117 119 120 121 74 74 75 76 77 78 78
95 117 118 119 121 123 124 125 78 78 79 80 81 82 82
99 124 125 127 129 130 132 132 86 86 87 88 89 90 90
12 50 101 102 104 106 108 109 110 59 60 61 62 63 63 64
90 115 116 118 120 121 123 123 74 75 75 76 77 78 79
95 119 120 122 123 125 127 127 78 79 80 81 82 82 83
99 126 127 129 131 133 134 135 86 87 88 89 90 90 91
13 50 104 105 106 108 110 111 112 60 60 61 62 63 64 64
90 117 118 120 122 124 125 126 75 75 76 77 78 79 79
95 121 122 124 126 128 129 130 79 79 80 81 82 83 83
99 128 130 131 133 135 136 137 87 87 88 89 90 91 91
14 50 106 107 109 111 113 114 115 60 61 62 63 64 65 65
90 120 121 123 125 126 128 128 75 76 77 78 79 79 80
95 124 125 127 128 130 132 132 80 80 81 82 83 84 84
99 131 132 134 136 138 139 140 87 88 89 90 91 92 92
15 50 109 110 112 113 115 117 117 61 62 63 64 65 66 66
90 122 124 125 127 129 130 131 76 77 78 79 80 80 81
95 126 127 129 131 133 134 135 81 81 82 83 84 85 85
99 134 135 136 138 140 142 142 88 89 90 91 92 93 93
16 50 111 112 114 116 118 119 120 63 63 64 65 66 67 67
90 125 126 128 130 131 133 134 78 78 79 80 81 82 82
95 129 130 132 134 135 137 137 82 83 83 84 85 86 87
99 136 137 139 141 143 144 145 90 90 91 92 93 94 94
17 50 114 115 116 118 120 121 122 65 66 66 67 68 69 70
90 127 128 130 132 134 135 136 80 80 81 82 83 84 84
95 131 132 134 136 138 139 140 84 85 86 87 87 88 89
99 139 140 141 143 145 146 147 92 93 93 94 95 96 97
To use the table, first plot the child’s height on a standard growth curve ( www.cdc.gov/growthcharts ). The child’s measured systolic blood pressure (SBP) and diastolic blood pressure (DBP) are compared with the numbers provided in the table according to the child’s age and height percentile.

TABLE 17.3
Blood Pressure Levels for Girls by Age and Height Percentile
(From National High Blood Pressure Education Program Working Group on High Blood Pressure in Children and Adolescents. The fourth report on the diagnosis, evaluation, and treatment of high blood pressure in children and adolescents. National Heart, Lung, and Blood Institute, Bethesda, MD 2005; National Institute of Health publication 05:5267.)
Blood Pressure Systolic Blood Pressure (mm Hg) Diastolic Blood Pressure (mm Hg)
Percentile ← Percentile of Height → ← Percentile of Height →
Age (Years) ↓ 5 10 25 50 75 90 95 5 10 25 50 75 90 95
1 50 83 84 85 86 88 89 90 38 39 39 40 41 41 42
90 97 97 98 100 101 102 103 52 53 53 54 55 55 56
95 100 101 102 104 105 106 107 56 57 57 58 59 59 60
99 108 108 109 111 112 113 114 64 64 65 65 66 67 67
2 50 85 85 87 88 89 91 91 43 44 44 45 46 46 47
90 98 99 100 101 103 104 105 57 58 58 59 60 61 61
95 102 103 104 105 107 108 109 61 62 62 63 64 65 65
99 109 110 111 112 114 115 116 69 69 70 70 71 72 72
3 50 86 87 88 89 91 92 93 47 48 48 49 50 50 51
90 100 100 102 103 104 106 106 61 62 62 63 64 64 65
95 104 104 105 107 108 109 110 65 66 66 67 68 68 69
99 111 111 113 114 115 116 117 73 73 74 74 75 76 76
4 50 88 88 90 91 92 94 94 50 50 51 52 52 53 54
90 101 102 103 104 106 107 108 64 64 65 66 67 67 68
95 105 106 107 108 110 111 112 68 68 69 70 71 71 72
99 112 113 114 115 117 118 119 76 76 76 77 78 79 79
5 50 89 90 91 93 94 95 96 52 53 53 54 55 55 56
90 103 103 105 106 107 109 109 66 67 67 68 69 69 70
95 107 107 108 110 111 112 113 70 71 71 72 73 73 74
99 114 114 116 117 118 120 120 78 78 79 79 80 81 81
6 50 91 92 93 94 96 97 98 54 54 55 56 56 57 58
90 104 105 106 108 109 110 111 68 68 69 70 70 71 72
95 108 109 110 111 113 114 115 72 72 73 74 74 75 76
99 115 116 117 119 120 121 122 80 80 80 81 82 83 83
7 50 93 93 95 96 97 99 99 55 56 56 57 58 58 59
90 106 107 108 109 111 112 113 69 70 70 71 72 72 73
95 110 111 112 113 115 116 116 73 74 74 75 76 76 77
99 117 118 119 120 122 123 124 81 81 82 82 83 84 84
8 50 95 95 96 98 99 100 101 57 57 57 58 59 60 60
90 108 109 110 111 113 114 114 71 71 71 72 73 74 74
95 112 112 114 115 116 118 118 75 75 75 76 77 78 78
99 119 120 121 122 123 125 125 82 82 83 83 84 85 86
9 50 96 97 98 100 101 102 103 58 58 58 59 60 61 61
90 110 110 112 113 114 116 116 72 72 72 73 74 75 75
95 114 114 115 117 118 119 120 76 76 76 77 78 79 79
99 121 121 123 124 125 127 127 83 83 84 84 85 86 87
10 50 98 99 100 102 103 104 105 59 59 59 60 61 62 62
90 112 112 114 115 116 118 118 73 73 73 74 75 76 76
95 116 116 117 119 120 121 122 77 77 77 78 79 80 80
99 123 123 125 126 127 129 129 84 84 85 86 86 87 88
11 50 100 101 102 103 105 106 107 60 60 60 61 62 63 63
90 114 114 116 117 118 119 120 74 74 74 75 76 77 77
95 118 118 119 121 122 123 124 78 78 78 79 80 81 81
99 125 125 126 128 129 130 131 85 85 86 87 87 88 89
12 50 102 103 104 105 107 108 109 61 61 61 62 63 64 64
90 116 116 117 119 120 121 122 75 75 75 76 77 78 78
95 119 120 121 123 124 125 126 79 79 79 80 81 82 82
99 127 127 128 130 131 132 133 86 86 87 88 88 89 90
13 50 104 105 106 107 109 110 110 62 62 62 63 64 65 65
90 117 118 119 121 122 123 124 76 76 76 77 78 79 79
95 121 122 123 124 126 127 128 80 80 80 81 82 83 83
99 128 129 130 132 133 134 135 87 87 88 89 89 90 91
14 50 106 106 107 109 110 111 112 63 63 63 64 65 66 66
90 119 120 121 122 124 125 125 77 77 77 78 79 80 80
95 123 123 125 126 127 129 129 81 81 81 82 83 84 84
99 130 131 132 133 135 136 136 88 88 89 90 90 91 92
15 50 107 108 109 110 111 113 113 64 64 64 65 66 67 67
90 120 121 122 123 125 126 127 78 78 78 79 80 81 81
95 124 125 126 127 129 130 131 82 82 82 83 84 85 85
99 131 132 133 134 136 137 138 89 89 90 91 91 92 93
16 50 108 108 110 111 112 114 114 64 64 65 66 66 67 68
90 121 122 123 124 126 127 128 78 78 79 80 81 81 82
95 125 126 127 128 130 131 132 82 82 83 84 85 85 86
99 132 133 134 135 137 138 139 90 90 90 91 92 93 93
17 50 108 109 110 111 113 114 115 64 65 65 66 67 67 68
90 122 122 123 125 126 127 128 78 79 79 80 81 81 82
95 125 126 127 129 130 131 132 82 83 83 84 85 85 86
99 133 133 134 136 137 138 139 90 90 91 91 92 93 93
To use the table, first plot the child’s height on a standard growth curve ( www.cdc.gov/growthcharts ). The child’s measured systolic blood pressure (SBP) and diastolic blood pressure (DBP) are compared with the numbers provided in the table according to the child’s age and height percentile.

The National High Blood Pressure Education Program Working Group and the European Society of Hypertension both recommend documentation of elevated pressures at three visits before making the diagnosis of hypertension in children and adolescents. The value of obtaining readings on three occasions before classifying a child as hypertensive was first noted in the 1970s and has been confirmed in more recent studies. For example, in a school-based screening using the 2004 National High Blood Pressure Education Working Group guidelines, McNiece et al found that the prevalence of elevated BPs fell from 9.4% to 3.2% by the third visit. Also, the importance of obtaining multiple readings at each encounter has been verified by previous investigators. BP may drop with subsequent measurement between the vital sign station and the examination room. The pressure improves as a result of reduction in anxiety with repeated readings and regression to the mean. Certainly in symptomatic children or those with marked BP elevation the above mentioned delay in initiating an evaluation and treatment pending verification at multiple visits would not be appropriate. This is recognized in the Fourth Report, which allows for more immediate diagnosis and treatment in those with symptomatic or severely elevated BP.

Measuring the Blood Pressure

Casual Blood Pressure Measurement

Accurate measurement of the BP is critical and can be challenging. Important points to consider include: type of device, appropriate cuffing, and environmental/positional factors. Mercury manometers have been removed from widespread clinical practice but accurate readings can be obtained with properly maintained aneroid devices. Casual manual readings may be compromised by improper technique, tendency to round off readings, failure to allow adequate rest before measurement, and background noise. As in adults, K5 is used to determine the diastolic reading in children. The reader is directed to an excellent review of the technique of ausculatory measurement for more details. Oscillometric devices offer convenience, objectivity, and are particularly helpful in infants. However, the monitors rapidly inflate to high levels, which may lead to discomfort and be counterproductive by upsetting young children. The first reading is almost always higher than subsequent readings. Measurement may be difficult or impossible in moving or uncooperative children or in those with arrhythmias. Lastly, oscillometric BP monitors detect the oscillations of the artery during inflation of the cuff with maximum oscillations occurring at the mean arterial pressure. Systolic and diastolic values are then back-calculated based on proprietary formulas that vary between machines. Validation of these devices in pediatric populations is not universal and should be confirmed before use, particularly in younger children.

The American Society of Hypertension and the International Society of Hypertension recently indicated that automated readings are preferred over manual readings because of concerns over the inaccuracy of auscultated readings. However, the measurements used to generate the pediatric BP tables were obtained by auscultation. Several studies in children have demonstrated that oscillometric measurements tend to be higher and do not correlate well with auscultated readings. Thus for consistency, continued use of carefully obtained auscultated readings in the pediatric population for confirmation of hypertension is recommended.

Cuff size is very important and cannot be judged based on the manufacturer’s labeling. The width of the bladder should cover at least 40% of the circumference of the arm measured midway between the olecranon and the acromion. The length of the bladder should cover 80% to 100% of the circumference of the upper arm, resulting in a bladder width to length ratio of 1:2. Arm size designations on the cuff can be misleading and cuff size should be selected based on the arm circumference. Finding an appropriate cuff can be difficult in infants and in obese adolescents. Use of wrist and forearm cuffs is not recommended because pediatric thresholds are based on readings obtained in the upper arm. Inappropriately sized cuffs can lead to erroneous readings, with the greatest issue being obtaining falsely high readings if the cuff is too small.

Lastly, BPs should be taken in a quiet environment after allowing the patient to rest for at least 5 minutes. The patient should be seated with the back supported, feet on the floor, and the arm positioned such that the brachial artery is at heart level. Two to three readings should be taken about one minute apart. Readings should be obtained in both arms. Pressures in the right arm may be higher than the left in those with coarctation of the aorta. If the readings are similar the right arm should be used subsequently for consistency. Leg pressures are obtained at least once in children to exclude coarctation of the aorta or midaortic syndrome. The measurements should be obtained after the patient has been lying down for 5 minutes and are compared with supine arm readings. Measurements in one leg and the right arm are sufficient. Leg pressures typically exceed arm pressures by 10 mm Hg or more and if lower than arm pressures, abnormalities of the aorta should be considered. Standing BPs are not typically considered part of the evaluation unless orthostatic symptoms are reported.

Ambulatory Blood Pressure Monitoring

Ambulatory BP monitoring (ABPM) is increasingly recognized as a valid and valuable procedure in the evaluation of elevated casual office BP readings in children. In the United Kingdom and Canada ABPM is recommended in all adults to confirm the diagnosis of hypertension. Such a universal recommendation has not been made for the pediatric population to date. However, several studies have demonstrated the benefits and cost savings of this procedure as a means of detecting white coat hypertension, thus obviating the need for an extensive diagnostic evaluation. White coat hypertension is reported in up to 46% of children and adolescents investigated for hypertension. Although home BP measurement may be helpful in excluding white coat hypertension, ABPM offers a more complete assessment of the BP pattern over the course of the day because it obtains readings during day-to-day activities and while asleep. Additional issues with home BP measurement include the scarcity of data on normal values in children and the lack of consistent validation of devices in the pediatric population. As with casual readings, thresholds defining hypertension on ABPM are not limited to one threshold for awake and asleep periods as in adults. Guidelines on performance and interpretation of ABPM in the pediatric population were recently updated and include height and gender-specific 95th percentiles along with recommendations for interpretation. Recordings are classified based on mean systolic/diastolic readings and the BP load (percent of readings above the threshold). An ABPM study is classified as demonstrating sustained hypertension if the mean systolic and/or diastolic pressures are above threshold. If BP loads are above 50% the ABPM is further classified as showing severe ambulatory hypertension. An ABPM study is classified as indicating prehypertension if the mean systolic and/or diastolic pressures are below threshold but the pressure loads are above 25%. As mentioned above in regard to home monitors, there are many ABPM devices on the market but few are actually validated in the pediatric population; it is important to investigate this issue when planning provision of this service. Although ABPM has been used in very young children, we generally reserve this procedure for children ages 7 and up. As shown in Fig. 17.1 , at Seattle Children’s Hospital we use ABPM as the first step in our evaluation of elevated BPs for children 7 years or older. Only those with sustained hypertension on ABPM or confirmed stage 2 hypertension in the office undergo a full evaluation, as discussed later. For those with white coat hypertension or prehypertension, lifestyle modifications and repeat ABPM in one year are recommended.

FIG. 17.1, Suggested algorithm for outpatient clinic evaluation of elevated blood pressure (BP) in children 7 years of age or older. Basic evaluation: Electrolytes, blood urea nitrogen, creatinine, calcium, lipid panel, urinalysis, echocardiogram, renal ultrasound. If overweight or obese add fasting glucose. Consider sleep study if obese and concerns for obstructive sleep apnea. Full evaluation: If strong suspicion of secondary hypertension or BP very high, complete basic evaluation and consider other tests listed in Table 17.6 as indicated.

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