Overview
Definition:
Hypertension secondary to renal parenchymal disease in children refers to elevated blood pressure resulting from structural or functional abnormalities of the kidney parenchyma itself, rather than renovascular causes
This is a common cause of secondary hypertension in pediatric populations.
Epidemiology:
Secondary hypertension accounts for a significant proportion of hypertension in children, estimated at 60-80%
Renal parenchymal diseases are the leading cause, seen in approximately 50-75% of children with secondary hypertension
Prevalence varies with underlying etiology and geographic region.
Clinical Significance:
Untreated or poorly controlled hypertension in children can lead to serious long-term complications including left ventricular hypertrophy, stroke, renal damage, vision loss, and cardiovascular disease in adulthood
Early identification and management are crucial for preventing morbidity and mortality
Understanding this specific etiology is vital for pediatricians preparing for DNB and NEET SS exams.
Clinical Presentation
Symptoms:
Asymptomatic in many cases, detected on routine screening
Headaches, particularly morning headaches
Visual disturbances like blurred vision or transient visual loss
Irritability or behavioral changes
Seizures, especially in severe cases
Nocturia or enuresis
Nausea or vomiting
Shortness of breath due to fluid overload or heart failure.
Signs:
Elevated blood pressure readings, consistently above the 95th percentile for age, sex, and height
Bruit heard over the abdomen or flanks (less common in parenchymal disease compared to renovascular)
Signs of fluid overload: peripheral edema, pulmonary rales, jugular venous distension
Funduscopic examination may reveal papilledema, hemorrhages, or cotton wool spots in severe hypertension.
Diagnostic Criteria:
Diagnosis of hypertension in children is based on repeated blood pressure measurements exceeding established thresholds (e.g., ≥95th percentile) according to guidelines (e.g., AAP, ESC)
The diagnosis of secondary hypertension due to renal parenchymal disease is confirmed by identifying the underlying renal pathology and exclusion of other causes of secondary hypertension.
Diagnostic Approach
History Taking:
Detailed birth history (gestational age, complications)
History of urinary tract infections (UTIs), congenital anomalies of the kidney and urinary tract (CAKUT), hematuria, proteinuria, or flank pain
Family history of kidney disease or hypertension
Medications or exposure to nephrotoxic agents
Growth parameters (failure to thrive or growth deceleration)
Presence of systemic symptoms suggestive of underlying conditions (e.g., rash, joint pain in vasculitis)
Red flags: sudden onset hypertension, severe hypertension, resistant hypertension, evidence of target organ damage.
Physical Examination:
Accurate BP measurement in both upper and lower extremities
General examination: growth parameters, signs of dysmorphism
Cardiovascular examination: heart sounds, murmurs, edema
Abdominal examination: palpation for masses, renal bruits
Neurological examination: for signs of hypertensive encephalopathy
Funduscopic examination.
Investigations:
Urinalysis: proteinuria, hematuria, casts (red cell casts in glomerulonephritis, white cell casts in pyelonephritis)
Urine culture: to rule out infection
Renal function tests: serum creatinine, BUN, electrolytes (hyponatremia, hyperkalemia may be present)
Complete blood count: anemia may be present in chronic kidney disease
Serum albumin and calcium/phosphate levels
Imaging: Renal ultrasound is the initial imaging modality to assess kidney size, shape, echogenicity, and rule out structural abnormalities like hydronephrosis or cysts
Doppler ultrasound may be used if renovascular hypertension is suspected but less likely for primary parenchymal disease
CT or MRI may be indicated for detailed anatomical assessment if ultrasound is inconclusive
Radionuclide scans (e.g., DMSA) can assess renal scarring
Biopsy of the kidney may be required for definitive diagnosis of specific parenchymal diseases (e.g., glomerulonephritis, interstitial nephritis).
Differential Diagnosis:
Primary (essential) hypertension (less common in young children), renovascular hypertension, endocrine causes (pheochromocytoma, Cushing's syndrome, hyperaldosteronism), coarctation of the aorta, sleep apnea, drug-induced hypertension
Specific renal parenchymal diseases include glomerulonephritis (post-infectious, IgA nephropathy, lupus nephritis), chronic pyelonephritis with renal scarring, polycystic kidney disease, obstructive uropathy, interstitial nephritis.
Management
Initial Management:
Immediate control of severe hypertension (hypertensive urgency/emergency) with intravenous antihypertensive agents (e.g., nicardipine, labetalol, hydralazine) to prevent acute target organ damage
Identification and treatment of any precipitating factors or infections.
Medical Management:
Pharmacological therapy is crucial and tailored to the specific renal parenchymal disease and the degree of hypertension
Common classes of antihypertensives include: ACE inhibitors (e.g., enalapril, ramipril) or ARBs (e.g., losartan, valsartan) are often first-line as they also offer renal protection
Calcium channel blockers (e.g., amlodipine, nifedipine)
Diuretics (e.g., furosemide, hydrochlorothiazide) are useful for volume management and in patients with reduced GFR
Beta-blockers (e.g., propranolol, atenolol) may be used, especially if there is a cardiac component
Combination therapy is often required
Dosage adjustments are necessary based on renal function
Treatment aims to reduce BP to target levels (e.g., <90th percentile for age in most cases, lower if target organ damage is present).
Surgical Management:
Rarely indicated for hypertension directly due to parenchymal disease, unless there is a surgically correctable associated anomaly like severe hydronephrosis or a localized mass causing pressure effects
Management is primarily medical and focused on treating the underlying renal pathology.
Supportive Care:
Dietary modifications: low-sodium diet is essential
Fluid management to avoid overload
Regular monitoring of blood pressure, renal function, and electrolytes
Education of the child and family about the condition, treatment adherence, and lifestyle modifications
Referral to a pediatric nephrologist and possibly a cardiologist or ophthalmologist for management of complications.
Complications
Early Complications:
Hypertensive encephalopathy (seizures, confusion, coma)
Acute pulmonary edema
Acute kidney injury
Retinopathy (hemorrhages, exudates, papilledema)..
Late Complications:
Chronic kidney disease progression to end-stage renal disease requiring dialysis or transplantation
Left ventricular hypertrophy
Cardiovascular disease (e.g., myocardial infarction, stroke)
Visual impairment or blindness
Poor growth and development.
Prevention Strategies:
Early detection of renal parenchymal disease through screening of at-risk children
Prompt diagnosis and treatment of UTIs and other renal insults
Strict adherence to antihypertensive medication regimens and regular follow-up
Lifestyle modifications including salt restriction and weight management.
Prognosis
Factors Affecting Prognosis:
Severity of the underlying renal disease
Degree of hypertension and its control
Presence of proteinuria and its progression
Early initiation of treatment
Presence of co-morbid conditions
Adherence to treatment.
Outcomes:
With timely diagnosis and effective management, blood pressure can be controlled, and the progression of renal damage can be slowed or halted in many cases
However, some children may develop progressive renal insufficiency and require renal replacement therapy
Long-term cardiovascular outcomes are improved with good BP control.
Follow Up:
Lifelong follow-up is generally required
This includes regular BP monitoring, assessment of renal function (serum creatinine, GFR, urinalysis), electrolyte balance, and screening for cardiovascular complications
Frequency of follow-up depends on the stability of the condition and severity of the renal disease.
Key Points
Exam Focus:
Recognize renal parenchymal disease as the leading cause of secondary hypertension in children
Key investigations include urinalysis, renal function tests, and renal ultrasound
ACE inhibitors and ARBs are often first-line due to dual benefit
Strict BP control is paramount to prevent long-term complications.
Clinical Pearls:
Always measure BP in both arms and legs in a child with suspected hypertension
A low-sodium diet is fundamental
Monitor for signs of fluid overload
Educate parents on medication adherence and the importance of regular follow-ups
Remember that hypertension can be a harbinger of underlying serious renal pathology.
Common Mistakes:
Attributing hypertension solely to essential hypertension in a child without thorough investigation
Delaying referral to a pediatric nephrologist
Inadequate BP control leading to target organ damage
Underestimating the impact of dietary salt intake
Failing to adjust medication doses based on renal function.