Etiologies of Arterial Hypertension in Children
In children, secondary hypertension predominates as the primary etiology, with renal parenchymal disease and renovascular disorders being the most common causes, though primary (essential) hypertension is increasingly recognized, particularly in children over 5-6 years of age who are overweight or have a positive family history 1.
Age-Dependent Etiology Pattern
The underlying cause of hypertension in children follows a clear age-related pattern:
- Younger children (< 6 years): Secondary causes are overwhelmingly predominant, requiring thorough investigation for underlying pathology
- Older children and adolescents (≥ 6 years): Primary hypertension becomes more common, especially when obesity or family history is present 1, 2
Major Categories of Secondary Hypertension
Renal Causes (Most Common)
Renal parenchymal and renovascular etiologies represent the leading causes of secondary hypertension in children 1. These include:
- Chronic kidney disease
- Renal artery stenosis
- Polycystic kidney disease
- Glomerulonephritis
- Reflux nephropathy
Endocrine Causes
Adrenal disorders frequently underlie secondary hypertension 3:
Mineralocorticoid excess:
- Congenital Adrenal Hyperplasia (11β-hydroxylase deficiency - CYP11B1 mutations)
- Congenital Adrenal Hyperplasia (17-hydroxylase deficiency - CYP17A1 mutations)
- Familial Hyperaldosteronism (gene fusion of CYP11B1 and CYP11B2, or mutations in CLCN2, KCNJ5, CACNA1H, CACNA1D)
Glucocorticoid excess:
- Cushing's syndrome
Catecholamine excess:
- Pheochromocytomas/paragangliomas (may be part of familial syndromes with germline mutations)
Peripheral hormone pathway disorders:
- 11β-dehydrogenase type 2 deficiency (HSD-11B2 mutations)
- Glucocorticoid and mineralocorticoid receptor mutations (NR3C1, NR3C2)
Cardiovascular Causes
- Aortic coarctation or arch obstruction 4
- Other congenital heart defects
Obesity-Related Primary Hypertension
The childhood obesity epidemic has led to a rising incidence of primary hypertension 5, 2. This represents a shift in the epidemiologic landscape, with essential hypertension now constituting a substantial proportion of cases in school-age children and adolescents.
Clinical Approach to Identifying Etiology
High-Risk Populations Requiring Investigation
According to AAP guidelines, blood pressure should be checked at every encounter in children with 4:
- Obesity
- Medications known to increase BP
- Renal disease
- History of aortic arch obstruction or coarctation
- Diabetes
Diagnostic Workup Strategy
For secondary hypertension, antihypertensive treatment should be initiated at the outset along with evaluation 1. The workup should be guided by:
- Age of presentation: Younger age increases likelihood of secondary causes
- Severity of hypertension: Stage 2 hypertension warrants more aggressive investigation
- Presence of symptoms or signs: Target organ damage, growth abnormalities, specific syndromic features
Ambulatory blood pressure monitoring (ABPM) is strongly recommended for:
- Confirming persistent hypertension
- Identifying masked hypertension
- Detecting absence of nocturnal dipping (both are significant prognostic markers of cardiovascular morbidity) 1, 5
Important Caveats
- White coat hypertension must be excluded before extensive workup, as it is common in children 4
- ABPM provides superior diagnostic accuracy compared to office measurements and helps differentiate hypertension phenotypes 5
- The distinction between primary and essential hypertension is a diagnosis of exclusion—secondary causes must be systematically ruled out 2
Emerging Considerations
Novel insights into pathogenesis include the role of perinatal factors and cardiovascular biomarkers such as fibroblast growth factor 23, though these require further evaluation 5. The prevalence of pediatric hypertension is approximately 4-5% worldwide, with peak incidence at adolescence 1, 5.