Overview
Definition:
Pediatric hypertension is defined as an average systolic and/or diastolic blood pressure that is greater than or equal to the 95th percentile for age, sex, and height on three or more occasions
This definition is based on established reference values, such as those from the Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents
Isolated elevated readings during a single clinic visit do not confirm the diagnosis
serial measurements are crucial
Primary (essential) hypertension is increasingly recognized in children, but secondary causes remain common and are often treatable.
Epidemiology:
The prevalence of hypertension in children and adolescents varies widely depending on the population studied and the diagnostic criteria used, ranging from 1% to over 5%
Primary hypertension accounts for the majority of cases in older children and adolescents, while secondary hypertension is more prevalent in younger children and infants
Obesity is a significant risk factor for primary hypertension in pediatric populations
Untreated hypertension in childhood can lead to long-term cardiovascular complications, including left ventricular hypertrophy, chronic kidney disease, and stroke.
Clinical Significance:
Recognizing and managing hypertension in children is critical for preventing irreversible end-organ damage and reducing the risk of premature cardiovascular disease in adulthood
Early identification and intervention can significantly alter the long-term health trajectory of affected individuals
A thorough understanding of secondary causes is paramount, as their prompt diagnosis and treatment can lead to complete resolution of hypertension
Ambulatory Blood Pressure Monitoring (ABPM) plays a vital role in accurate diagnosis and management.
Diagnostic Approach
History Taking:
A comprehensive history should focus on identifying risk factors for primary hypertension and clues to secondary causes
Key elements include: Family history of hypertension, cardiovascular disease, or kidney disease
Detailed birth history (prematurity, intrauterine growth restriction, perinatal complications)
Diet and lifestyle (high sodium intake, obesity, physical inactivity, sweetened beverage consumption)
Symptoms suggestive of secondary causes: headaches, visual disturbances, epistaxis (pheochromocytoma, renal artery stenosis)
Abdominal masses or bruits (neuroblastoma, Wilms tumor, renal artery stenosis)
Weak or absent femoral pulses (coarctation of the aorta)
Polydipsia, polyuria, failure to thrive (renal disease, endocrine disorders)
Medication use (steroids, sympathomimetics, oral contraceptives)
Red flags include hypertension in infants/young children, very high blood pressure readings, hypertension resistant to multiple medications, and signs of end-organ damage.
Physical Examination:
A systematic physical examination is essential
It should include: Accurate measurement of blood pressure in both arms and legs (especially if coarctation is suspected), using appropriately sized cuffs
Growth assessment (height, weight, BMI, plotting on growth charts)
Cardiovascular examination (murmurs, gallops, peripheral pulses, checking for coarctation of the aorta by comparing upper and lower extremity BP)
Abdominal examination (palpable masses, bruits)
Funduscopic examination (hypertensive retinopathy)
Neurological examination (if indicated by symptoms)
Examination for stigmata of specific syndromes (e.g., Cushingoid features, ambiguous genitalia).
Investigations:
Initial investigations aim to confirm hypertension, identify target organ damage, and screen for common secondary causes: **Blood Pressure Measurement:** Serial BP measurements in a quiet environment using calibrated devices
**Ambulatory Blood Pressure Monitoring (ABPM):** The gold standard for diagnosing sustained hypertension, evaluating diurnal BP patterns, and identifying white-coat hypertension or masked hypertension
It involves automated BP measurements every 15-30 minutes during the day and every 30-60 minutes at night over a 24-hour period
Normal daytime BP < 90th percentile, nocturnal dipping of 10-20%
**Laboratory Tests:** Urinalysis (proteinuria, hematuria, glucosuria)
Basic metabolic panel (serum creatinine, electrolytes, BUN) to assess renal function and electrolyte balance
Complete blood count
Lipid profile
Fasting blood glucose or HbA1c
**Screening for Secondary Causes:** **Renal Ultrasound:** To assess kidney size, structure, and rule out structural abnormalities
**Renal Artery Doppler Ultrasound:** To screen for renal artery stenosis
**Echocardiogram:** To assess for left ventricular hypertrophy and other cardiac abnormalities
**Hormonal Assays (if indicated):** Plasma renin activity, aldosterone levels (primary aldosteronism)
urine or plasma catecholamines and metanephrines (pheochromocytoma)
serum cortisol, dexamethasone suppression test (Cushing's syndrome)
17-hydroxyprogesterone (congenital adrenal hyperplasia)
**Imaging for specific causes:** CT or MRI of abdomen/pelvis (neuroblastoma, Wilms tumor)
aortography or CT angiography (coarctation of aorta, renal artery stenosis).
Differential Diagnosis:
The differential diagnosis for hypertension in children includes: **Primary (Essential) Hypertension:** Increasingly common, often associated with obesity and family history
**Secondary Hypertension:** A broad category including: **Renal Parenchymal Disease:** Glomerulonephritis, polycystic kidney disease, reflux nephropathy
**Renovascular Hypertension:** Renal artery stenosis (atherosclerotic, fibromuscular dysplasia, congenital)
**Endocrine Disorders:** Primary aldosteronism, Cushing's syndrome, pheochromocytoma, congenital adrenal hyperplasia, hyperthyroidism, hypothyroidism
**Vascular Abnormalities:** Coarctation of the aorta, aberrant subclavian artery
**Neurologic Disorders:** Increased intracranial pressure, Guillain-Barré syndrome
**Medications:** Steroids, sympathomimetics, oral contraceptives
**Obstructive Sleep Apnea:** A common contributor to resistant hypertension
**Genetic Syndromes:** Williams syndrome, neurofibromatosis
Distinguishing features often lie in the age of onset, severity of hypertension, presence of specific symptoms, and physical examination findings.
Ambulatory Blood Pressure Monitoring
Purpose:
ABPM is crucial for confirming the diagnosis of sustained hypertension, differentiating it from white-coat hypertension, identifying masked hypertension, and assessing the effectiveness of antihypertensive therapy
It provides a more comprehensive picture of a child's BP profile than office readings alone.
Indications:
Indications for ABPM in children include: Suspected white-coat hypertension (elevated clinic BP with normal home/ambulatory readings)
Suspected masked hypertension (normal clinic BP with elevated home/ambulatory readings)
Evaluation of resistant hypertension (BP above target despite ≥3 antihypertensive medications, including a diuretic)
Assessment of nocturnal dipping patterns
Monitoring antihypertensive treatment efficacy
Hypertension in children with specific comorbidities like diabetes or chronic kidney disease.
Interpretation:
ABPM data is interpreted by comparing average daytime, nighttime, and 24-hour BP readings to age-, sex-, and height-specific percentile charts
Key parameters include: **Average systolic and diastolic BP:** Compared to percentiles for age, sex, and height
**Blood Pressure Load:** Percentage of readings above the 95th percentile
**Diurnal Variation:** The normal pattern involves a significant drop in BP during sleep (nocturnal dipping), typically 10-20%
Non-dippers or extreme dippers may have increased cardiovascular risk
**Masked Hypertension:** Normal clinic BP, elevated 24-hour ABPM
**White-Coat Hypertension:** Elevated clinic BP, normal 24-hour ABPM
**Sustained Hypertension:** Elevated clinic BP and elevated 24-hour ABPM.
Secondary Causes Of Hypertension
Renal Parenchymal Disease:
Common causes include chronic glomerulonephritis, polycystic kidney disease, and chronic pyelonephritis
These conditions lead to impaired sodium excretion and activation of the renin-angiotensin-aldosterone system (RAAS)
Diagnosis relies on urinalysis, renal function tests, and renal imaging.
Renovascular Hypertension:
Narrowing of the renal arteries reduces blood flow to the kidneys, stimulating RAAS
Causes include fibromuscular dysplasia (most common in children and young adults) and atherosclerosis
Key features are often severe hypertension, a renal artery bruit, and electrolyte abnormalities (hypokalemia with secondary hyperaldosteronism)
Diagnosis is made via Doppler ultrasound, CT angiography, or MR angiography.
Endocrine Disorders:
These include primary aldosteronism (Conn's syndrome), Cushing's syndrome, pheochromocytoma, congenital adrenal hyperplasia, and hyperthyroidism
Each has specific hormonal profiles and clinical manifestations that guide diagnosis through targeted laboratory testing and imaging.
Coarctation Of The Aorta:
A congenital narrowing of the aorta, typically distal to the left subclavian artery
Presents with hypertension in the upper extremities and hypotension in the lower extremities, with diminished or absent femoral pulses
A continuous or systolic murmur may be heard in the back
Diagnosis is confirmed by echocardiography or cross-sectional imaging.
Other Causes:
These encompass genetic syndromes (e.g., Williams syndrome), neurological disorders, and various medications
A thorough history and physical examination, guided by suspected etiologies, are key to identifying these less common but treatable causes.
Management
Initial Management:
The initial management involves lifestyle modifications and pharmacological therapy
Lifestyle changes are fundamental and include dietary adjustments (reduced sodium intake, DASH diet), weight management, increased physical activity, and smoking cessation (for adolescents)
Pharmacological therapy is initiated based on the BP level and the presence of target organ damage or comorbidities
The choice of antihypertensive medication depends on the child's age, race, and the presence of secondary causes.
Medical Management:
Antihypertensive drug classes recommended for children include: **Diuretics:** Thiazide diuretics (e.g., hydrochlorothiazide, chlorthalidone) are often first-line agents, especially for primary hypertension
**ACE inhibitors (ACEIs) and Angiotensin II Receptor Blockers (ARBs):** Effective and well-tolerated, particularly useful in children with proteinuria or diabetes
Examples: Lisinopril, Enalapril (ACEIs)
Losartan, Valsartan (ARBs)
**Calcium Channel Blockers (CCBs):** Dihydropyridines (e.g., amlodipine) are effective for managing systolic hypertension
Non-dihydropyridines (e.g., diltiazem, verapamil) can also be used, especially if there is concomitant tachycardia or supraventricular arrhythmias
**Beta-blockers:** Less commonly used as first-line agents unless there is a specific indication like congenital heart disease or hypertrophic cardiomyopathy
Examples: Metoprolol, Atenolol
**Dosage adjustments are crucial** based on age, weight, and response
Treatment of secondary causes often resolves the hypertension, but some may require concurrent antihypertensive therapy.
Management Of Secondary Causes:
The management strategy is dictated by the specific secondary cause
**Renal artery stenosis:** Angioplasty or surgical revascularization may be considered
**Coarctation of the aorta:** Surgical repair or balloon angioplasty
**Pheochromocytoma:** Surgical resection, often preceded by alpha-adrenergic blockade
**Primary aldosteronism:** Aldosterone antagonists (spironolactone, eplerenone)
**Cushing's syndrome:** Surgical removal of the tumor or medical management to reduce cortisol production
Prompt identification and treatment of these causes can lead to normalization of blood pressure and prevent long-term complications.
Complications
Target Organ Damage:
Untreated or poorly controlled hypertension can lead to significant end-organ damage in children, mirroring adult complications
This includes: **Cardiovascular System:** Left ventricular hypertrophy (LVH), diastolic dysfunction, premature coronary artery disease, heart failure
**Renal System:** Proteinuria, hematuria, chronic kidney disease, end-stage renal disease
**Cerebrovascular System:** Stroke (ischemic or hemorrhagic), transient ischemic attacks
**Ocular System:** Hypertensive retinopathy (retinal hemorrhages, exudates, papilledema).
Long Term Sequelae:
Children with hypertension are at increased risk for developing sustained hypertension into adulthood, significantly raising their lifetime risk of cardiovascular events like myocardial infarction, stroke, and aortic dissection
Early detection and aggressive management can mitigate these long-term risks.
Prevention Strategies:
Prevention focuses on addressing modifiable risk factors from an early age: promoting healthy dietary habits (low sodium, fruits, vegetables), encouraging regular physical activity, maintaining a healthy weight, and avoiding exposure to tobacco smoke
Early screening for hypertension in at-risk children (e.g., those with obesity, family history, or congenital anomalies) is also crucial.
Key Points
Exam Focus:
Understand the definition of hypertension in children based on percentiles
Master the indications and interpretation of ABPM
Differentiate primary vs
secondary hypertension based on age and clinical features
Recognize common secondary causes and their key diagnostic clues (renal, endocrine, vascular)
Know the first-line antihypertensive agents for children
Recognize the importance of lifestyle modifications.
Clinical Pearls:
Always measure BP in both arms and legs in suspected cases of coarctation
Consider ABPM for any child with borderline elevated clinic BP or resistant hypertension
Think secondary cause in very young children or those with sudden onset of severe hypertension
Don't forget obstructive sleep apnea as a contributor to resistant hypertension
Treat the underlying secondary cause whenever possible for a potential cure.
Common Mistakes:
Diagnosing hypertension based on a single elevated reading
Using adult BP cuff sizes on children
Underestimating the prevalence of primary hypertension in older children/adolescents
Failing to investigate for secondary causes when indicated
Inadequate dosage titration of antihypertensive medications
Neglecting the importance of lifestyle modifications in management.