Hypertension in Children

Definition and Staging

• Defined statistically based on distribution in healthy children.
• Based on age, sex, and height percentiles (American Academy of Pediatrics 2017 Guidelines).
• Revised normative data excludes overweight/obese children, lowering diagnostic cut-offs by 2-3 mm Hg.

Clinic Blood Pressure Staging

Category	Children Aged 1 to 13 Years	Children Aged $\ge$ 13 Years
Normal BP	<90th percentile.	<120/<80 mm Hg.
Elevated BP	$\ge$ 90th percentile to <95th percentile.	120/<80 to 129/<80 mm Hg.
Stage 1 Hypertension	$\ge$ 95th percentile to <95th percentile + 12 mm Hg.	130/80 to 139/89 mm Hg.
Stage 2 Hypertension	$\ge$ 95th percentile + 12 mm Hg.	$\ge$ 140/90 mm Hg.

Ambulatory Blood Pressure Monitoring (ABPM) Staging

Category	Clinic SBP/DBP	Mean Ambulatory SBP/DBP
Normal	<95th percentile.	<95th percentile.
White Coat Hypertension	$\ge$ 95th percentile.	<95th percentile.
Masked Hypertension	<95th percentile.	$\ge$ 95th percentile.
Ambulatory Hypertension	$\ge$ 95th percentile.	$\ge$ 95th percentile.

Epidemiology and Disease Burden

• Prevalence increasing parallel to childhood obesity epidemic.
• ~11% children/adolescents possess abnormal BP; 3-4% have hypertension; 10% have elevated BP.
• Primary hypertension commonly affects older school-age children and adolescents.
• Secondary hypertension accounts for ~90% of cases in infants/young children.
• Tracks into adulthood; increases risk of premature cardiovascular/kidney disease.
• Children with BP >90th percentile exhibit 2.4-fold greater risk of adult hypertension.

Etiology and Pathophysiology

• Blood pressure product of cardiac output (CO) and peripheral vascular resistance (PVR).

Primary (Essential) Hypertension

• Multifactorial etiology: Obesity, insulin resistance, sympathetic nervous system activation, renin-angiotensin-aldosterone system (RAAS) disorders, altered sodium homeostasis, vascular smooth muscle reactivity.
• Elevated uric acid levels implicated.
• Associated with family history of hypertension.
• Salt-sensitive hypertension common; ameliorated by sodium restriction/weight loss.

Secondary Hypertension

Category	Associated Conditions
Renal (Most Common)	Chronic glomerulonephritis, pyelonephritis/renal scarring, congenital dysplastic/polycystic kidney disease, vesicoureteral reflux nephropathy, obstructive nephropathy, hemolytic-uremic syndrome (HUS), Wilms tumor, Ask-Upmark kidney.
Vascular	Coarctation of the aorta (thoracic/abdominal), renal artery stenosis, fibromuscular dysplasia, thrombosis, Takayasu arteritis, systemic lupus erythematosus vasculitis, Kawasaki disease.
Endocrine	Hyperthyroidism (systolic HTN/tachycardia), hypothyroidism, hyperparathyroidism (hypercalcemia), congenital adrenal hyperplasia (CAH), Cushing syndrome, primary aldosteronism, pheochromocytoma, neuroblastoma.
Monogenic/Genetic	Liddle syndrome, Gordon syndrome, apparent mineralocorticoid excess, glucocorticoid-remediable aldosteronism (low renin).
Neurologic	Increased intracranial pressure, Guillain-Barré syndrome, autonomic storm (spinal cord injury), familial dysautonomia, posterior fossa lesions, encephalitis.
Transient/Intermittent	Acute postinfectious glomerulonephritis, Henoch-Schönlein purpura, HUS, acute kidney injury, hypervolemia, pain/anxiety, hypercalcemia.
Drugs/Toxins	Cocaine, amphetamines, sympathomimetics, corticosteroids, oral contraceptives, calcineurin inhibitors (cyclosporine, tacrolimus), licorice, heavy metals (lead, mercury), Vitamin D intoxication.

Clinical Manifestations

Asymptomatic Presentation

• Usually asymptomatic in primary hypertension.
• Identified during routine preventive visits or pre-participation athletic screening.

Symptomatic Presentation

• Common with secondary hypertension or severe BP elevation.
• Symptoms: Headache, dizziness, irritability, epistaxis, anorexia, visual changes, seizures.
• Severe elevation consequences: Cardiac failure, pulmonary edema, kidney dysfunction.

Hypertensive Emergency and Encephalopathy

• Definition: Severe hypertension accompanied by acute target-organ injury.
• Encephalopathy (PRES - Posterior Reversible Encephalopathy Syndrome): Vomiting, high temperature, ataxia, stupor, seizures, visual disturbances (cortical blindness).
• Exam findings: Cranial nerve palsies, papilledema, retinal hemorrhages, rapid kidney function deterioration.

Subclinical Target-Organ Damage (TOD)

• Left ventricular hypertrophy (LVH): Most common TOD; present in up to 40% of hypertensive children.
• Increased carotid intima-media thickness (cIMT).
• Retinopathy and microalbuminuria.
• Reduced neurocognitive performance; reversible with treatment.

Diagnostic Evaluation

Blood Pressure Measurement Protocol

• Recommended for all children $\ge$ 3 years during annual preventive visits.
• Check at every encounter if risk factors present (obesity, CKD, diabetes, aortic arch obstruction, taking BP-elevating meds).
• Check in children <3 years with specific risks: Prematurity, congenital heart disease, solid-organ transplant, malignancy, systemic illnesses (neurofibromatosis, tuberous sclerosis), increased ICP.
• Technique: Auscultation preferred. Resting seated position for 5-10 minutes. Right arm preferred. Measure at least twice and average.
• Cuff selection crucial: Inflatable bladder width ~40% of arm circumference; length covering 80-100% of upper arm circumference.
• Coarctation screen: Measure BP in both arms and one leg. Leg systolic BP normally 10-20 mm Hg higher than arm. Lower leg pressure suggests coarctation.

History and Physical Examination

System/Category	Findings & Potential Relevance
General	Pale mucous membranes, edema, growth retardation (Chronic kidney disease). Elfin facies, upturned nose (Williams syndrome). Webbed neck, wide carrying angle (Turner syndrome). Moon face, buffalo hump, striae (Cushing syndrome).
Habitus	Thinness (Pheochromocytoma, hyperthyroidism, severe renal disease). Obesity (Primary hypertension, Metabolic syndrome).
Head, Neck, Eyes	Fundal changes (chronic severe HTN), Proptosis (Hyperthyroidism), Goiter (Thyroid disease), Adenotonsillar hypertrophy (Sleep-disordered breathing).
Cardiovascular	Absent/diminished femoral pulses, radial-femoral delay, right arm > leg BP gradient (Aortic coarctation). Bruits over abdomen/great vessels (Arteritis/renovascular disease).
Abdomen	Hepatomegaly, abdominal mass (Neuroblastoma, Wilms tumor, polycystic kidneys), epigastric/renal bruit.
Genitourinary	Ambiguous/virilized genitalia (Congenital adrenal hyperplasia - 11$\beta$ or 17$\alpha$ hydroxylase deficiency).
Neuromuscular	Muscle weakness (Hyperaldosteronism, Liddle syndrome/hypokalemia). Cafe-au-lait spots, neurofibromas (Neurofibromatosis - associated with pheochromocytoma/renal artery stenosis).

Ambulatory Blood Pressure Monitoring (ABPM)

• Superior predictor of target-organ damage compared to clinic BP.
• Indications: Confirming hypertension diagnosis, diagnosing white coat or masked hypertension, assessing treatment effectiveness, evaluating high-risk populations (CKD, solid-organ transplant, diabetes, severe obesity).
• Detects abnormal diurnal patterns (lack of 10% nocturnal dip).

Laboratory and Imaging Studies

Tier	Indication	Recommended Studies
Tier 1 (All confirmed HTN $\ge$ 90th percentile)	Rule out renal disease/mineralocorticoid excess	BUN, Creatinine, Electrolytes (potassium), Urinalysis, Urine culture.
Tier 2 (Comorbidities / $\ge$ 95th percentile)	Identify hyperlipidemia, metabolic abnormalities	Fasting lipid panel, Fasting glucose, HbA1c, Liver function tests (for overweight/obese). Complete blood count (rule out chronic disease anemia).
Tier 3 (Target Organ Damage)	Assess LVH prior to initiating pharmacotherapy	Echocardiogram: Assess LV mass, function, screen for coarctation. LVH defined as LV mass >51 g/m2.7 (>8 yrs) or >115 g/BSA (boys <8 yrs) / >95 g/BSA (girls <8 yrs).
Tier 4 (Secondary Causes)	Identify renal scarring, structural anomalies, disparities	Renal Ultrasound (Indicated for all <6 yrs, or abnormal urinalysis/renal function).
Tier 5 (Specialized/High Suspicion)	Suspected renovascular disease, pheochromocytoma	Doppler ultrasonography, CT/MR Angiography (Renovascular). Plasma/urine catecholamines, Plasma renin/aldosterone, Plasma/urine steroids. Polysomnography (Sleep-disordered breathing).

Management Strategies

Treatment Goals

• General pediatric goal: Reduce BP <90th percentile for age/sex/height or <130/80 mm Hg (whichever is lower).
• Chronic Kidney Disease (CKD): Stricter goal; 24-hour MAP <50th percentile on ABPM.

Therapeutic Lifestyle Interventions (Primary Therapy)

• Indicated for all patients (elevated BP and hypertension).
• Dietary Modification: DASH diet implementation. High in fresh fruits, vegetables, fiber, nonfat dairy. Reduced total and saturated fats. Avoid sugar-sweetened beverages.
• Sodium Restriction: Limit to 1.2 g/day (4-8 years) and 1.5 g/day (older children). AHA recommends <1500 mg/day for high-risk patients.
• Physical Activity: 30-60 minutes (goal $\ge$ 5 hours/week) of moderate-to-vigorous aerobic exercise daily.
• Sedentary Limitation: Restrict recreational screen time to <2 hours/day.
• Weight Reduction: Primary therapy for obesity-related hypertension. Significant BP reduction achievable.

Pharmacologic Therapy

Indications

• Symptomatic hypertension.
• Stage 2 hypertension without modifiable risk factors.
• Secondary hypertension.
• Hypertension complicated by Target-Organ Damage (e.g., LVH).
• Presence of Diabetes Mellitus (Type 1 or 2) or Chronic Kidney Disease.
• Failure of non-pharmacologic interventions (3-6 months trial).

Stepped-Care Approach

• Step 1: Initiate single agent at lowest recommended dose.
• Step 2: Titrate dose every 2-4 weeks until BP goal achieved or maximum dosage reached.
• Step 3: Add second medication with complementary mechanism of action if single agent maxed out.
• Step 4: Add third agent of different class if dual therapy fails.

Common Outpatient Antihypertensive Agents

Drug Class	Agents	Pediatric Dosing	Clinical Comments
ACE Inhibitors (ACEi)	Captopril, Enalapril, Lisinopril	Captopril: 0.1-0.5 mg/kg/dose (max 6 mg/kg/day). Lisinopril: 0.07 mg/kg/day (max 40 mg/day).	Preferred in diabetes, proteinuria, CKD. Side effects: Dry cough, hyperkalemia, neutropenia. Teratogenic (avoid in females of childbearing age).
Angiotensin Receptor Blockers (ARB)	Losartan, Valsartan, Irbesartan	Losartan: 0.7 mg/kg/day (max 100 mg/day).	Alternative to ACEi. Preferred for diabetes/CKD. Teratogenic.
Calcium Channel Blockers (CCB)	Amlodipine, Isradipine, Nifedipine (ER)	Amlodipine: 0.1 mg/kg/day (max 10 mg/day). Isradipine: 0.05-0.15 mg/kg/dose.	Highly effective. Side effects: Headache, flushing, dizziness, peripheral edema, reflex tachycardia.
Beta-Blockers	Metoprolol, Atenolol	Metoprolol: 1-6 mg/kg/day (bid). Atenolol: 0.5-2 mg/kg/day.	Avoid in asthma/heart failure. May blunt hypoglycemia symptoms in diabetics.
Alpha/Beta Antagonists	Labetalol, Carvedilol	Labetalol: 1-3 mg/kg/day (bid) (max 1200 mg/day).	Useful in mixed therapy. Monitor for orthostasis.
Diuretics	Furosemide, Hydrochlorothiazide (HCTZ)	HCTZ: 0.5-1 mg/kg/day (qd). Furosemide: 0.5-6 mg/kg/day.	Add-on therapy. Side effects: Hypokalemia, dyslipidemia, hyperuricemia (HCTZ).
Central Alpha Agonists	Clonidine	Clonidine: 5-25 mcg/kg/day.	Sedation common. Abrupt cessation causes rebound hypertension.

Management of Hypertensive Emergencies

• Setting: Intensive Care Unit with continuous intra-arterial BP monitoring.
• Goal: Reduce BP by up to 25% over the first 8 hours (~10% in the first hour). Followed by gradual reduction over the next 24-36 hours. Rapid reduction precipitates cerebral ischemia.
• Volume Status: Assess and correct volume depletion (due to pressure natriuresis) to prevent precipitous BP fall upon vasodilation.

Intravenous Antihypertensive Agents for Severe Hypertension

Medication	Mechanism	Dose	Side Effects & Cautions
Labetalol	$\alpha$ and $\beta$ blocker	IV infusion: 0.25-3 mg/kg/hr. IV bolus: 0.2-1 mg/kg/dose.	Bradycardia, orthostatic hypotension, bronchospasm. Avoid in asthma.
Nicardipine	Calcium Channel Blocker	IV infusion: 0.5-4 mcg/kg/min.	Preferred agent due to efficacy and safety. Flushing, reflex tachycardia, phlebitis.
Sodium Nitroprusside	Direct Vasodilator	IV infusion: 0.5-8 mcg/kg/min.	Rapid onset (30 sec). Cyanide/thiocyanate toxicity (monitor in prolonged use/renal failure).
Esmolol	Selective $\beta 1$ blocker	IV loading: 100-500 mcg/kg. Infusion: 50-500 mcg/kg/min.	Rapid onset/short half-life (9 min). Profound bradycardia/hypotension.