Definitions of pediatric prehypertension and hypertension
Children's blood pressure norms were first established in 1977 by the
Task Force for Blood Pressure in Children, with a revision in 1987 by a second
task force. This second task force added more ethnic groups to their data. The
second task force recommendations were revisited in 1996, and included height in
the blood pressure categories.[7] These guidelines were more recently modified
in 2004 and contain the following definitions of normal, prehypertensive and
hypertensive blood pressure levels in children and adolescents.[8]
• Normal blood pressure:
systolic and/or diastolic blood pressure levels <90th percentile for gender,
age and height
• Prehypertension: systolic
and/or diastolic blood pressure levels ≥90th percentile but <95th percentile
for gender, age and height
• Prehypertension in adolescents:
blood pressure ≥120/80 mm Hg, as in adults, even if this value is <90th
percentile for gender, age and height
• Hypertension: systolic
and/or diastolic blood pressures ≥95th percentile for gender, age and height,
measured on 3 separate occasions
The most recent pediatric blood pressure tables are accessible online.[8]
They are divided by sex and age, ranging from 1 to 17 years. Within each age,
the blood pressure upper limits are listed under the 50th, 90th, 95th and
99th percentiles. These are further subdivided by the height
percentile, between 5th to 95th percentiles, by the standard growth
curves.
Accurate measurement
Choosing appropriately sized blood pressure cuff is critical in the
diagnosis of hypertension in children. If a cuff used is too small, hypertension
is incorrectly diagnosed. Or, if a cuff is too large, hypertension can be
missed. Standard cuff sizes are available for a neonate, infant, small child,
child, adult, large adult. A thigh cuff may also be needed. The appropriately
sized cuff's bladder width should be approximately 40% of the circumference of
the arm. The markings that indicate the bladder width can be found on the inside
of a blood pressure cuff. The bladder length should be approximately 80% of the
circumference of the arm. If the cuff is too small, the next larger size cuff
should be used.[8]
The blood pressure should be obtained in the right upper extremity. The
bottom of the blood pressure cuff should be approximately 2 cm above the cubital
fossa. The cubital fossa resting should be at the level of heart. The blood
pressure should be taken after 3 to 5 minutes of rest. It should be taken twice,
using the average as the blood pressure level for diagnosis. The systolic blood
pressure is when the "tapping" sound begins. The diastolic blood pressure is the
5th Korotkoff sound, which is when the tapping sound disappears.[7] If the blood
pressure is difficult to auscultate, especially in the infant population, a
Doppler can be used.[9] Auscultation is the standard by which the blood pressure
tables were created.[8] If an oscillometric device is used and the patient is
noted to be hypertensive, this must be confirmed by auscultation.
Recommended timing
As recommended by the American Academy of Pediatrics, blood pressure
measurement should begin routinely at the 3-year well child visit and be
repeated yearly. However, there are certain historical or physical exam findings
that may indicate the need to check blood pressure levels at an earlier age. For
example, if the femoral pulses are difficult to palpate at any age, a right
upper extremity and lower extremity blood pressure in either leg should be
checked. Also if there is a history of a neonatal intensive care stay, a family
history of congenital renal disease, a family history of congenital heart
disease, recurrent urinary tract infections, known renal malformations,
transplantations or other systemic diseases associated with hypertension, right
upper extremity should be checked at an age earlier than 3 years.[8]
If the patient's blood pressure is between the 90th and 95th percentiles,
in the prehypertensive category, recheck it in 6 months.[8] Encourage lifestyle
changes, especially if the patient is obese.
If the blood pressure is greater than 95th percentile, these
patients should have a blood pressure recheck in 1 to 2 weeks. If blood pressure
levels continue to be elevated, but under the 99th percentile on 2 more
occasions, these patients have stage 1 hypertension and need an appropriate
referral for further work-up within 1 month (see below). If the blood pressure
readings are greater than the 99th percentile, the patient is in the stage 2
hypertension category and needs a referral to the appropriate team within 1
week, or immediately if the patient is symptomatic.[8]
Potential causes of pediatric hypertension
Obtaining a complete physical examination and a clear past medical and
family history is essential in narrowing down the potential causes for the
hypertension. Typically, patients with primary hypertension are older,
overweight, have mild or stage 1 hypertension and have a positive family
history. Patients with secondary causes are typically younger, have stage 2
hypertension and may have other physical signs of systemic
disease.[10-12]
Renal problems are very common causes for preadolescent hypertension.
Renal artery stenosis constitutes 8%–10% of the underlying causes of
hypertension in young children. There is a higher suspicion for renal artery
stenosis with a history of umbilical artery placement during the newborn period.
Renal parenchymal disease can occur from scarring from reoccurring urinary tract
infections. This is typically seen later in the first decade of life. Failure to
thrive can be indicative of a renal cause.
Approximately one-third of hypertension cases in infants are due to a
coarctation of the aorta.[13] In these infants, femoral pulse palpation will be
diminished when compared to the brachial pulses. In addition to obtaining a
right upper extremity blood pressure, a lower extremity blood pressure should be
obtained.
Obesity in the adolescent has a clear association with primary
hypertension. In patients with obesity, sleep disorders are becoming more a
concern than hypertension.[8] A history of snoring and apnea should be
addressed. There is also a link between a family history of hypertension and
primary hypertension in adolescence.
Further evaluation
As mentioned previously, further work-up is needed for all children whose
blood pressure is greater than the 95th percentile. This work-up is based on
whether primary or secondary hypertension is suspected. The specific work-up for
secondary hypertension may include urine analysis to assess for proteinuria and
hematuria, and a renal ultrasound to assess for structural or renal artery
abnormalities. If the femoral pulses are diminished, an echocardiogram may be
ordered to assess for coarctation of the aorta and to detect left ventricular
hypertrophy.
For primary hypertension, laboratory evaluation should check for other
cardiovascular risk factors, since they tend to cluster. Hypertension and
overweight are part of the insulin-resistance syndrome, which includes many risk
factors for heart disease and type 2 diabetes.
Summary
Early identification of prehypertension and hypertension in children and
adolescents has become increasingly important as elevated blood pressure is on
the rise in this population and calls for prompt intervention. The diagnosis of
hypertension can be daunting in children because secondary causes are more
prevalent than in adults, especially in younger children with more severe
hypertension. Using the most recent pediatric blood pressure tables and the
recommendations on how to properly take a blood pressure can make the first
steps easier. Combined with a comprehensive medical history, family history and
physical examination, the possible secondary diagnosis can be narrowed further,
leading to the proper referral.
References
[1.] Sorof
JM, Lai D, Turner J, et al. Overweight, ethnicity, and the prevalence of
hypertension in school-aged children. Pediatrics
2004;113:475-482.
[2.] Hansen ML, Gunn PW, Kaelber DC. Underdiagnosis of hypertension in
children and adolescents. JAMA 2007;298(8):874-879.
[3.] Kay JD, Sinaiko
AR, Daniels SR. Pediatric
hypertension. Am Heart J 2001;142:422-432.
[4.] Mahoney LT, Clarke WR, Burns TL. Childhood predictors of high blood
pressure. Am J Hypertens 1991;4:608-610.
[5.] MacMahon S, Peto R, Cutler J, et al. Blood pressure, stroke, and
coronary heart disease, prolonged differences in blood pressure, prospective
observational studies correction for the regression dilution bias. Lancet
1990;335;765-774.
[6.] Klag MJ, Whelton
PK, Randall BL, et al. Blood pressure and end-stage
renal disease in men. N Engl J Med 1996;334;13-18.
[7.] National High Blood Pressure Education Program Working Group on
Hypertension Control in Children and Adolescents. Update on the 1987 task force
report on high blood pressure in children and adolescents: A working group
report from the National High Blood Pressure Education Program. Pediatrics
1996;98:649-658.
[8.] 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. Pediatrics 2004;114(suppl):555-576. Full
text
and blood pressure tables available at:
http://pediatrics.aappublications.
org/cgi/content/full/114/2/S2/555. Accessed September 22,
2008.
[9.] Rowan S, Adrogues H, Mathur A, Kamat D. Pediatric hypertension: A
review for primary care provider. Clin Pediatr 2005;44:289-296.
[10.] Bartosh SM, Aronson AJ. Childhood hypertension. Pediatr Clin North
Am 1999;46(2)235-252.
[11.] Sorof J, Daniels S. Obesity and hypertension in children: A problem
of epidemic proportions. Hypertension 2002;40:441-447.
[12.] Ogden CL, Flegal KM, Carroll MD, et al.
Prevalence and trends in overweight US children and adolescents, 1999-2000. JAMA
2002;288:1728-1732.
[13.] Norwood VF. Hypertension. Pediatr Rev
2002;23(6):197-208. | 
