Systemic Hypertension

KEY WORDS

Blood pressure
Exercise
Guideline
Heart
Kidney
Left ventricular hypertrophy
Obesity
Sodium

Hypertension is one of the most common chronic diseases in adults, affecting about 30% of adults of all ages and 7.3% of young adults 18 to 39 years of age.¹,² In children <18 years of age, however, hypertension is much less common, with recent screening studies demonstrating a 3% to 4% prevalence of persistent hypertension. Some studies have reported a higher prevalence of up to 5% in obese minority adolescents,³ reflecting a similar impact of the obesity epidemic as seen in adults.²,⁴ Other recent analyses have demonstrated an increase in prevalence of hypertension in children and adolescents ≤18 years of age, again likely because of the obesity epidemic.⁵ On the other hand, the prevalence of hypertension in those ≥18 years of age has remained stable over time.²

Most adolescents and adults with hypertension have primary hypertension—that is, no identifiable underlying cause can be found for their blood pressure (BP) elevation. Since most hypertensive adolescents and young adults (AYAs), particularly those with primary hypertension, are asymptomatic, it is imperative to measure BP whenever an adolescent or young adult is seen for health care in order to detect hypertension and institute appropriate measures to reduce cardiovascular risk.

DEFINITION OF HYPERTENSION

The cardiovascular end points used to define hypertension in adults (e.g., myocardial infarction, stroke) do not occur in children and adolescents. Therefore, the definition of hypertension in those <18 years of age is a statistical one derived from analysis of a large database of BPs obtained from healthy children.⁶ The resulting normative BP values for adolescents ≤17 years of age are listed in Tables 17.1 and 17.2. To use these tables, height should first be obtained and plotted on a standard growth curve to determine the height percentile. Then, the gender-appropriate chart should be used to determine the BP percentile. BP readings ≥95th percentile are considered hypertensive in this age group, and should be staged (see below) and repeated as appropriate (see Table 17.3). Elevated BP readings ≥95th percentile on three or more occasions are required to make a diagnosis of hypertension.⁵

For young adults ≥18 years, any BP reading ≥140/90 is considered hypertensive, regardless of age or gender. Individuals with BP values of this magnitude on two or more occasions are considered to have hypertension.⁷

Prehypertension

Common to both the pediatric (<18 years of age) and adult BP classification schemes is the concept of “prehypertension,” referring to BPs between the normal and hypertensive ranges. Although the term has proved to be controversial, it is meant to serve as an alert to patients and physicians to the potential for future development of hypertension and of the need to make lifestyle changes that might prevent this from occurring. The same BP value of >120/80 mm Hg is used in both adolescents and adults to designate prehypertension.

Staging

Also common to both the pediatric and adult BP classification schemes is the concept of “staging” the severity of hypertension. The staging system helps to determine how rapidly a hypertensive patient should be evaluated and when antihypertensive drug therapy should be initiated. The currently accepted staging systems for hypertension in AYAs⁶,⁷ are compared in Table 17.3.

FACTORS THAT INFLUENCE BP

Height and Weight

Height is part of the definition of normative BP in patients ≤17 years of age⁶; its inclusion was based on statistical analysis of the childhood BP database. Others hold that weight is the most important factor in determining BP. Weight has long been shown to have a positive relationship with BP, as demonstrated in a study of adolescent Minneapolis school children.⁸ Increased body mass index (BMI) is also one of the most important influences on BP in adults ≥18 years old.²

Age

BP increases with age in a nonlinear manner through adolescence; this is likely related to growth. Beyond adolescence, BP, especially systolic BP (SBP), continues to increase in a significant percentage of individuals as the result of genetic and environmental factors, as well as age-associated vascular changes.

Sodium and Other Dietary Constituents

Numerous studies have done little to settle the controversy concerning the relationship of sodium intake to BP. For most individuals, little correlation exists. However, in certain salt-sensitive individuals, sodium restriction appears beneficial.⁹ Decreased sodium intake on a population basis might be more beneficial¹⁰; a recent study demonstrated that reducing dietary sodium intake in England was accompanied by a reduction in population BP levels.¹¹

TABLE 17.1 BP Values for Adolescent Boys 17 Years or Younger

		Systolic BP (mm Hg)							Diastolic BP (mm Hg)
Age (y)	BP Percentile	← Percentile of Height →							← Percentile of Height →
		5th	10th	25th	50th	75th	90th	95th	5th	10th	25th	50th	75th	90th	95th
10	50th	97	98	100	102	103	105	106	58	59	60	61	61	62	63
	90th	111	112	114	115	117	119	119	73	73	74	75	76	77	78
	95th	115	116	117	119	121	122	123	77	78	79	80	81	81	82
	99th	122	123	125	127	128	130	130	85	86	86	88	88	89	90
11	50th	99	100	102	104	105	107	107	59	59	60	61	62	63	63
	90th	113	114	115	117	119	120	121	74	74	75	76	77	78	78
	95th	117	118	119	121	123	124	125	78	78	79	80	81	82	82
	99th	124	125	127	129	130	132	132	86	86	87	88	89	90	90
12	50th	101	102	104	106	108	109	110	59	60	61	62	63	63	64
	90th	115	116	118	120	121	123	123	74	75	75	76	77	78	79
	95th	119	120	122	123	125	127	127	78	79	80	81	82	82	83
	99th	126	127	129	131	133	134	135	86	87	88	89	90	90	91
13	50th	104	105	106	108	110	111	112	60	60	61	62	63	64	64
	90th	117	118	120	122	124	125	126	75	75	76	77	78	79	79
	95th	121	122	124	126	128	129	130	79	79	80	81	82	83	83
	99th	128	130	131	133	135	136	137	87	87	88	89	90	91	91
14	50th	106	107	109	111	113	114	115	60	61	62	63	64	65	65
	90th	120	121	123	125	126	128	128	75	76	77	78	79	79	80
	95th	124	125	127	128	130	132	132	80	80	81	82	83	84	84
	99th	131	132	134	136	138	139	140	87	88	89	90	91	92	92
15	50th	109	110	112	113	115	117	117	61	62	63	64	65	66	66
	90th	122	124	125	127	129	130	131	76	77	78	79	80	80	81
	95th	126	127	129	131	133	134	135	81	81	82	83	84	85	85
	99th	134	135	136	138	140	142	142	88	89	90	91	92	93	93
16	50th	111	112	114	116	118	119	120	63	63	64	65	66	67	67
	90th	125	126	128	130	131	133	134	78	78	79	80	81	82	82
	95th	129	130	132	134	135	137	137	82	83	83	84	85	86	87
	99th	136	137	139	141	143	144	145	90	90	91	92	93	94	94
17	50th	114	115	116	118	120	121	122	65	66	66	67	68	69	70
	90th	127	128	130	132	134	135	136	80	80	81	82	83	84	84
	95th	131	132	134	136	138	139	140	84	85	86	87	87	88	89
	99th	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 SBP and DBP are compared with the numbers provided in the table according to the child’s age and height percentile. BP, blood pressure; SBP, systolic blood pressure; DBP, diastolic blood pressure. 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. NIH Publication 05-5267. Bethesda, MD: National Heart, Lung, and Blood Institute, 2005.

TABLE 17.2 BP Values for Adolescent Girl 17 Years or Younger

		Systolic BP (mm Hg)							Diastolic BP (mm Hg)
Age (y)	BP Percentile	← Percentile of Height →							← Percentile of Height →
		5th	10th	25th	50th	75th	90th	95th	5th	10th	25th	50th	75th	90th	95th
10	50th	98	99	100	102	103	104	105	59	59	59	60	61	62	62
	90th	112	112	114	115	116	118	118	73	73	73	74	75	76	76
	95th	116	116	117	119	120	121	122	77	77	77	78	79	80	80
	99th	123	123	125	126	127	129	129	84	84	85	86	86	87	88
11	50th	100	101	102	103	105	106	107	60	60	60	61	62	63	63
	90th	114	114	116	117	118	119	120	74	74	74	75	76	77	77
	95th	118	118	119	121	122	123	124	78	78	78	79	80	81	81
	99th	125	125	126	128	129	130	131	85	85	86	87	87	88	89
12	50th	102	103	104	105	107	108	109	61	61	61	62	63	64	64
	90th	116	116	117	119	120	121	122	75	75	75	76	77	78	78
	95th	119	120	121	123	124	125	126	79	79	79	80	81	82	82
	99th	127	127	128	130	131	132	133	86	86	87	88	88	89	90
13	50th	104	105	106	107	109	110	110	62	62	62	63	64	65	65
	90th	117	118	119	121	122	123	124	76	76	76	77	78	79	79
	95th	121	122	123	124	126	127	128	80	80	80	81	82	83	83
	99th	128	129	130	132	133	134	135	87	87	88	89	89	90	91
14	50th	106	106	107	109	110	111	112	63	63	63	64	65	66	66
	90th	119	120	121	122	124	125	125	77	77	77	78	79	80	80
	95th	123	123	125	126	127	129	129	81	81	81	82	83	84	84
	99th	130	131	132	133	135	136	136	88	88	89	90	90	91	92
15	50th	107	108	109	110	111	113	113	64	64	64	65	66	67	67
	90th	120	121	122	123	125	126	127	78	78	78	79	80	81	81
	95th	124	125	126	127	129	130	131	82	82	82	83	84	85	85
	99th	131	132	133	134	136	137	138	89	89	90	91	91	92	93
16	50th	108	108	110	111	112	114	114	64	64	65	66	66	67	68
	90th	121	122	123	124	126	127	128	78	78	79	80	81	81	82
	95th	125	126	127	128	130	131	132	82	82	83	84	85	85	86
	99th	132	133	134	135	137	138	139	90	90	90	91	92	93	93
17	50th	108	109	110	111	113	114	115	64	65	65	66	67	67	68
	90th	122	122	123	125	126	127	128	78	79	79	80	81	81	82
	95th	125	126	127	129	130	131	132	82	83	83	84	85	85	86
	99th	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 SBP and DBP are compared with the numbers provided in the table according to the child’s age and height percentile. BP, blood pressure; SBP, systolic blood pressure; DBP, diastolic blood pressure. 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. NIH Publication 05-5267. Bethesda, MD: National Heart, Lung, and Blood Institute, 2005.