Overview
Definition:
Pediatric hypertension (HTN) is persistently elevated blood pressure (BP) readings in children, defined as systolic and/or diastolic BP greater than or equal to the 90th percentile for age, sex, and height on at least three separate occasions
Workup aims to identify the etiology, which is frequently secondary in children, unlike essential HTN in adults.
Epidemiology:
The prevalence of HTN in children varies, with estimates ranging from 3-5% in the general pediatric population to over 30% in obese children
Secondary causes account for approximately 80-90% of childhood HTN, with renal and renovascular causes being the most common.
Clinical Significance:
Untreated pediatric HTN can lead to significant long-term morbidities, including left ventricular hypertrophy, cardiac events, renal damage, retinopathy, and neurocognitive deficits
Early identification and management are crucial to prevent these complications and promote healthy cardiovascular development.
Clinical Presentation
Symptoms:
Asymptomatic in many cases
Headaches, often occipital and worse in the morning
Visual disturbances
Dizziness
Nausea or vomiting
Fatigue
Irritability
Chest pain
Shortness of breath
Seizures (in hypertensive emergencies).
Signs:
Elevated blood pressure readings consistently above the 90th percentile for age, sex, and height
Bruits over the abdomen (suggestive of renovascular disease)
Diminished femoral pulses (coarctation of the aorta)
Funduscopic changes (papilledema, hemorrhages, exudates)
Signs of underlying pathology (e.g., edema in renal disease, abdominal mass in a tumor).
Diagnostic Criteria:
Diagnosis is based on standardized BP measurement protocols in children, typically using auscultatory methods with appropriately sized cuffs
Guidelines from organizations like the American Academy of Pediatrics (AAP) define HTN based on age- and sex-specific percentiles
Stage 1 HTN is defined as BP between the 90th and 95th percentile, while Stage 2 HTN is BP at or above the 95th percentile, often with target organ damage.
Diagnostic Approach
History Taking:
Detailed birth history (prematurity, low birth weight)
Family history of HTN, renal disease, or endocrine disorders
Diet (high sodium intake)
Medications (NSAIDs, steroids, oral contraceptives)
Symptoms suggestive of secondary causes: urinary tract infections, flank pain (renal parenchymal disease), recurrent infections, fever (renal infection), abdominal masses (tumors), neurological symptoms (CNS involvement).
Physical Examination:
Accurate BP measurement in all four limbs
Assess for coarctation of the aorta (femoral pulses, arm-leg BP differential)
Palpate abdomen for masses or organomegaly
Auscultate for abdominal bruits
Examine fundi for hypertensive retinopathy
Assess for edema, auscultate heart and lungs.
Investigations:
Initial investigations include urinalysis (proteinuria, hematuria, casts), complete blood count (anemia, infection), electrolytes (serum sodium, potassium, chloride, bicarbonate), BUN, creatinine, and urine electrolytes to assess renal function and rule out electrolyte imbalances
Renal ultrasound is crucial to assess kidney size, echogenicity, presence of structural anomalies, hydronephrosis, and to screen for renovascular disease (Doppler assessment)
Plasma renin activity and aldosterone levels are essential for evaluating hyperaldosteronism and secondary hyperaldosteronism due to renovascular hypertension
Further investigations may include a voiding cystourethrogram (VCUG) if recurrent UTIs are suspected, CT angiography or MR angiography for detailed evaluation of renal arteries, and endocrine workup (e.g., metanephrine levels for pheochromocytoma, cortisol for Cushing's syndrome) if clinically indicated.
Differential Diagnosis:
Primary (Essential) Hypertension: Less common in young children, typically in adolescents with risk factors like obesity
Renal Parenchymal Disease: Glomerulonephritis, chronic kidney disease, polycystic kidney disease
Renovascular Hypertension: Renal artery stenosis (atherosclerotic, fibromuscular dysplasia, congenital)
Endocrine Causes: Primary hyperaldosteronism (Conn's syndrome), Cushing's syndrome, pheochromocytoma, congenital adrenal hyperplasia
Coarctation of the Aorta: Classic cause of upper extremity HTN
Obstructive Sleep Apnea: Increasingly recognized cause, especially in obese children.
Renal Ultrasound And Renin Aldosterone
Renal Ultrasound Role:
A primary imaging modality for pediatric HTN workup
It helps detect structural abnormalities (e.g., renal hypoplasia, dysplastic kidneys, hydronephrosis, cysts), assess kidney size and echogenicity (suggestive of chronic damage), and identify signs of obstruction
Doppler ultrasound is vital for evaluating renal artery patency and flow, screening for renal artery stenosis (RAS) by assessing flow velocity, acceleration, and resistance indices.
Interpreting Renal Ultrasound:
Normal kidney size, smooth renal contour, and normal echogenicity are expected
Small, echogenic kidneys with blunted calyces suggest chronic renal disease
Hydronephrosis indicates obstruction
Absent or diminished Doppler signals, abnormal flow velocities, or delayed acceleration in the renal arteries can be indicative of RAS.
Renin Aldosterone Significance:
Measuring plasma renin activity (PRA) and aldosterone levels is crucial in identifying specific hormonal causes of HTN
High PRA with high aldosterone suggests secondary hyperaldosteronism, often due to renal artery stenosis or renin-secreting tumors
Low PRA with high aldosterone points towards primary hyperaldosteronism (e.g., adrenal adenoma, bilateral adrenal hyperplasia)
Normal or low PRA and low aldosterone suggest other causes of HTN.
Renin Aldosterone Interpretation:
In renovascular hypertension, renal artery stenosis leads to decreased renal perfusion, stimulating renin release from the juxtaglomerular apparatus, which in turn stimulates aldosterone secretion
This results in sodium and water retention, further exacerbating hypertension
Specific diagnostic algorithms exist for interpreting these hormone levels in conjunction with other clinical and laboratory findings.
Management
Initial Management:
Lifestyle modifications are fundamental, including dietary sodium restriction, weight management for overweight/obese children, and regular physical activity
Pharmacological management is initiated when BP remains elevated despite lifestyle changes or when HTN is severe.
Medical Management:
Antihypertensive agents are chosen based on the underlying cause and the child's age and comorbidities
First-line agents often include ACE inhibitors or ARBs (especially if renovascular or renal parenchymal disease is present), calcium channel blockers, and diuretics (thiazide diuretics)
Beta-blockers may be used for specific indications
Dosing must be carefully titrated to achieve target BP goals, which are often lower in children with secondary HTN or target organ damage
Specific pediatric dosing guidelines must be followed.
Surgical Management:
Surgical intervention is considered for specific secondary causes
Revascularization (angioplasty with stenting or surgical bypass) is the treatment for significant renal artery stenosis
Nephrectomy may be indicated for unilateral renal disease with refractory HTN or if the affected kidney is non-functional
Adrenalectomy may be performed for adrenal tumors causing HTN.
Supportive Care:
Close monitoring of BP, adherence to medications, and regular follow-up appointments are essential
Education of the child and family regarding the condition, treatment, and importance of lifestyle changes is critical for long-term management and prevention of complications.
Complications
Early Complications:
Hypertensive encephalopathy (seizures, altered mental status)
Hypertensive retinopathy (visual impairment, papilledema)
Acute kidney injury
Myocardial infarction or stroke (rare in children but possible with severe HTN or underlying risk factors)
Aortic dissection.
Late Complications:
Left ventricular hypertrophy leading to diastolic and systolic dysfunction
Chronic kidney disease and renal failure
Atherosclerosis and premature cardiovascular disease
Retinopathy leading to vision loss
Neurocognitive impairment.
Prevention Strategies:
Early detection through regular BP screening in children
Prompt identification and treatment of secondary causes of HTN
Strict adherence to prescribed antihypertensive medications and lifestyle modifications
Regular follow-up to monitor BP control and prevent target organ damage.
Prognosis
Factors Affecting Prognosis:
The prognosis depends largely on the underlying etiology of HTN, the severity and duration of untreated HTN, and the presence of target organ damage at diagnosis
Early diagnosis and effective management, particularly of secondary causes, lead to a significantly better outcome.
Outcomes:
With timely and appropriate management, many children can achieve normal or near-normal BP levels, with reversal or stabilization of target organ damage
However, some children may develop long-term complications despite treatment, especially if HTN was severe or prolonged before diagnosis.
Follow Up:
Lifelong follow-up is often required
Pediatric patients diagnosed with HTN need regular monitoring of BP, renal function, electrolytes, and cardiovascular status
The frequency of follow-up will depend on the severity of HTN, the underlying cause, and treatment response
Transition to adult care with adult nephrologists or cardiologists is crucial.
Key Points
Exam Focus:
Remember that most pediatric HTN is secondary, with renal and renovascular causes being paramount
Renal ultrasound is a cornerstone investigation for structural anomalies and RAS screening
Renin-aldosterone levels are key for differentiating hyperaldosteronism and assessing the renin-angiotensin system's role
Identify classic presentations of specific secondary causes.
Clinical Pearls:
Always measure BP in both arms and legs to rule out coarctation
A high index of suspicion for secondary HTN is warranted in children presenting with HTN, especially if they have a significant family history, abnormal physical findings, or evidence of target organ damage
Use age- and height-appropriate cuff sizes for accurate BP measurement.
Common Mistakes:
Attributing all pediatric HTN to essential hypertension without adequate workup
Inadequate BP measurement technique or cuff size
Missing subtle signs of secondary causes
Delaying or omitting crucial investigations like renal ultrasound and renin-aldosterone panels when indicated
Inadequate follow-up and adherence counseling.