Describe etiopathogenesis, grading, diagnostic evaluation and management of child with hypertension op thai pedia
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Based on the retrieved AAP 2017 guidelines ("Screening and Management of High Blood Pressure in Children and Adolescents") and comprehensive clinical knowledge, here is a detailed, structured answer aligned with the Thai Pediatric Society / OP Thai Pedia framework:
Hypertension in Children: Etiopathogenesis, Grading, Diagnostic Evaluation & Management
1. ETIOPATHOGENESIS
A. Classification by Etiology
Primary (Essential) Hypertension
- Most common in adolescents and older children (>10 years), especially overweight/obese
- No identifiable underlying cause
- Pathogenesis involves:
- Increased sympathetic nervous system activity → elevated cardiac output and peripheral resistance
- Renin-Angiotensin-Aldosterone System (RAAS) dysregulation → sodium retention, volume expansion
- Endothelial dysfunction → reduced nitric oxide (NO), increased endothelin
- Insulin resistance and hyperinsulinemia → sodium retention, sympathetic activation
- Genetic predisposition → polygenic; family history is a strong risk factor
- Obesity → adipokines (leptin, resistin) activate sympathetic axis; sleep apnea contributes
Secondary Hypertension
More common in young children (<6 years); always search for underlying cause.
| System | Causes |
|---|---|
| Renal (most common, ~70–80%) | Renal parenchymal disease (GN, chronic pyelonephritis, polycystic kidney disease, renal dysplasia), obstructive uropathy, hemolytic uremic syndrome, renal tumors |
| Renovascular | Renal artery stenosis (fibromuscular dysplasia, Takayasu arteritis, neurofibromatosis), renal vein thrombosis |
| Endocrine | Primary hyperaldosteronism, Cushing syndrome, congenital adrenal hyperplasia (11β-hydroxylase, 17α-hydroxylase deficiency), pheochromocytoma, hyperthyroidism, hyperparathyroidism |
| Cardiovascular | Coarctation of the aorta (classic cause in infants/young children) |
| Neurologic | Raised intracranial pressure, autonomic dysreflexia |
| Drugs/Toxins | Corticosteroids, cyclosporine, tacrolimus, cocaine, amphetamines, OCP, NSAIDs, decongestants |
| Monogenic syndromes | Liddle syndrome, Gordon syndrome (PHA2), apparent mineralocorticoid excess, glucocorticoid-remediable aldosteronism |
B. Pathophysiologic Mechanisms
- Volume overload (renal causes): ↑ sodium and water retention → ↑ preload → ↑ CO
- Elevated peripheral vascular resistance (renovascular, endocrine): vasoconstriction → ↑ afterload
- Neurogenic activation: SNS stimulation → ↑ HR, ↑ CO, vasoconstriction
- Hormonal excess: aldosterone → Na retention; catecholamines → vasoconstriction
2. GRADING / CLASSIFICATION
AAP 2017 Guidelines (Standard Used in Thailand)
Children <13 Years: Percentile-Based
| Category | Definition |
|---|---|
| Normal BP | SBP and DBP < 90th percentile |
| Elevated BP | SBP and/or DBP ≥ 90th to <95th percentile, OR ≥120/80 mmHg (even if <90th percentile) |
| Stage 1 Hypertension | SBP and/or DBP ≥ 95th to <95th + 12 mmHg, OR 130–139/80–89 mmHg |
| Stage 2 Hypertension | SBP and/or DBP ≥ 95th percentile + 12 mmHg, OR ≥140/90 mmHg |
BP percentiles are based on age, sex, and height percentile using AAP 2017 normative tables (derived from normal-weight children).
Adolescents ≥13 Years: Simplified (Aligned with Adult JNC/ACC/AHA)
| Category | BP Value |
|---|---|
| Normal | <120/<80 mmHg |
| Elevated BP | 120–129/<80 mmHg |
| Stage 1 HTN | 130–139/80–89 mmHg |
| Stage 2 HTN | ≥140/90 mmHg |
Hypertensive Crisis
| Type | Definition | Features |
|---|---|---|
| Hypertensive Urgency | Severely elevated BP without acute end-organ damage | Headache, nausea; no target organ damage |
| Hypertensive Emergency | Severely elevated BP with acute target organ damage | Encephalopathy, seizures, papilledema, AKI, pulmonary edema, cardiac failure |
Severe HTN = BP ≥ 95th percentile + 12 mmHg (or ≥140/90 in adolescents)
3. DIAGNOSTIC EVALUATION
A. BP Measurement (Correct Technique Critical)
- Use auscultatory method (gold standard); oscillometric devices should be confirmed with auscultation
- Cuff size: bladder width 40% of arm circumference; length 80–100% of arm circumference
- Child must be seated, rested ≥5 min, right arm at heart level
- Confirm elevated readings on 3 separate occasions before diagnosing hypertension (except emergencies)
- Ambulatory BP Monitoring (ABPM): recommended to confirm diagnosis, identify white coat HTN, masked HTN, and nocturnal dipping pattern
B. History
- Age of onset, duration, severity
- Symptoms: headache, visual changes, chest pain, palpitations, sweating, flushing (pheochromocytoma), polyuria, polydipsia
- Past medical history: recurrent UTIs, renal disease, prematurity (renovascular risk), umbilical artery catheter (neonatal renal artery thrombosis)
- Drug history: steroids, stimulants, OCP, decongestants
- Family history: hypertension, cardiovascular disease, renal disease, endocrine disorders
- Diet: salt intake, energy drinks, licorice
- Obesity risk factors, obstructive sleep apnea
C. Physical Examination
| Finding | Suggested Cause |
|---|---|
| Obesity, acne, striae | Cushing syndrome |
| Elfin facies, hypercalcemia | Williams syndrome |
| Café-au-lait spots | Neurofibromatosis (RAS) |
| Ambiguous genitalia | CAH |
| Abdominal bruits | Renovascular HTN |
| Femoral pulses weak/delayed, BP difference arms vs. legs | Coarctation of aorta |
| Palpable kidneys | PKD, hydronephrosis, Wilms tumor |
| Thyroid enlargement/exophthalmos | Hyperthyroidism |
| Papilledema, retinal changes | Target organ damage |
| Left ventricular heave | LVH |
D. Initial Laboratory Investigations
All children with confirmed HTN:
| Investigation | Purpose |
|---|---|
| Urinalysis + urine microscopy | Renal parenchymal disease (RBCs, casts, proteinuria) |
| Urine protein/creatinine ratio | Quantify proteinuria |
| Serum electrolytes (Na, K) | Hyperaldosteronism (hypokalemia), Gordon syndrome |
| BUN, creatinine, eGFR | Renal function |
| Fasting glucose, lipid profile | Metabolic syndrome, risk stratification |
| CBC | Anemia (CKD), polycythemia |
| Renal ultrasound | Kidney size, echogenicity, masses, hydronephrosis |
E. Additional Investigations (Based on Clinical Suspicion)
| Indication | Investigation |
|---|---|
| Suspected renovascular | Doppler renal ultrasound → DMSA/MAG3 → MR angiography → CT angiography → Renal angiography (gold standard) |
| Suspected pheochromocytoma | 24-hour urine catecholamines/metanephrines, plasma free metanephrines |
| Suspected primary hyperaldosteronism | Plasma aldosterone:renin ratio, adrenal CT |
| Suspected Cushing | 24-hour urine free cortisol, dexamethasone suppression test |
| Suspected CAH | Serum 17-OHP, androgen levels |
| Suspected coarctation | Echocardiogram, CXR (rib notching), MRI aorta |
| Suspected monogenic HTN | Genetic testing |
F. Target Organ Assessment
| Organ | Investigation | Finding |
|---|---|---|
| Heart | Echocardiogram (before starting medications) | LVH: LVMI ≥51 g/m²·⁷ (boys), ≥44 g/m²·⁷ (girls) |
| Eye | Fundoscopy | Keith-Wagener-Barker changes: AV nicking, hemorrhages, papilledema |
| Brain | MRI (if hypertensive encephalopathy) | PRES (posterior reversible encephalopathy) |
| Kidney | eGFR, urine protein | CKD, microalbuminuria |
| Vessels | Carotid IMT | Subclinical atherosclerosis |
4. MANAGEMENT
A. Therapeutic Goals
- BP < 90th percentile (age/sex/height) in children <13 years with primary HTN or no risk factors
- BP < 130/80 mmHg in adolescents ≥13 years
- For CKD/proteinuria: BP < 50th percentile (more aggressive)
- Prevent/reverse target organ damage (especially LVH regression)
B. Non-Pharmacological (Lifestyle) Management
First-line for Elevated BP and Stage 1 HTN without comorbidities or target organ damage:
| Intervention | Detail |
|---|---|
| Weight reduction | Most impactful — 10% weight loss can reduce SBP by 8–12 mmHg |
| DASH diet | High fruits, vegetables, low-fat dairy; low sodium, low saturated fat |
| Sodium restriction | <2,300 mg/day; <1,500 mg/day in severe HTN |
| Physical activity | 60 min/day moderate-to-vigorous aerobic exercise; avoid isometric exercise |
| Screen time reduction | <2 hours/day |
| Smoking/alcohol cessation | In adolescents |
| Sleep hygiene | Address obstructive sleep apnea |
Trial period: 3–6 months for Stage 1 HTN without target organ damage. If no response → escalate to pharmacological therapy.
C. Pharmacological Management
Indications for immediate drug therapy:
- Symptomatic HTN
- Stage 2 HTN
- HTN with target organ damage (LVH, retinopathy, CKD)
- HTN with diabetes mellitus
- Persistent Stage 1 HTN despite lifestyle modifications (≥6 months)
- Secondary HTN not corrected by treating the cause
First-Line Antihypertensive Agents in Children
| Drug Class | Examples | Notes |
|---|---|---|
| ACE Inhibitors (ACEi) | Enalapril, Lisinopril, Ramipril | Preferred in CKD with proteinuria, diabetes; contraindicated in bilateral RAS and pregnancy |
| ARBs | Losartan, Valsartan, Irbesartan | Alternative to ACEi; same indications; better tolerability (no cough) |
| Calcium Channel Blockers (CCB) | Amlodipine (DHP), Nifedipine | First-line in most children; safe, well-tolerated |
| Thiazide Diuretics | Hydrochlorothiazide, Chlorthalidone | Useful in volume-dependent HTN; caution in renal disease |
| Beta-Blockers | Atenolol, Metoprolol, Labetalol | Useful in high-output states, coarctation post-repair, migraine; avoid in asthma |
Special Situations
| Situation | Preferred Agent |
|---|---|
| CKD with proteinuria | ACEi or ARB |
| Coarctation of aorta | Beta-blocker or CCB (post-surgical) |
| Pheochromocytoma | Alpha-blocker (Phenoxybenzamine) first, then beta-blocker |
| Primary hyperaldosteronism | Spironolactone / surgery |
| Renovascular HTN | ACEi/ARB (with caution if bilateral) or CCB; revascularization |
| Obesity-related HTN | ACEi/ARB, CCB |
| Diabetes | ACEi or ARB |
D. Hypertensive Emergency Management
Goal: Reduce BP by no more than 25% of the planned reduction in the first 8 hours, then gradually over 24–48 hours. Avoid rapid overcorrection (risk of cerebral ischemia/watershed infarction).
| Drug | Route | Dose | Notes |
|---|---|---|---|
| Labetalol | IV infusion | 0.25–3 mg/kg/hr | Alpha + beta blocker; first-line |
| Sodium Nitroprusside | IV infusion | 0.5–8 µg/kg/min | Very potent; monitor cyanide toxicity |
| Nicardipine | IV infusion | 1–3 µg/kg/min | CCB; smooth, titratable |
| Hydralazine | IV bolus | 0.1–0.5 mg/kg/dose | Useful in neonates/infants |
| Enalaprilat | IV | 0.005–0.01 mg/kg/dose | ACEi; avoid in bilateral RAS |
| Nifedipine (sublingual) | SL/oral | 0.25 mg/kg | Used in urgency, not emergency (unpredictable) |
E. Follow-up
| BP Category | Follow-up Schedule |
|---|---|
| Elevated BP | Recheck in 1–3 months (lifestyle counseling initiated) |
| Stage 1 HTN (asymptomatic) | Recheck in 1–2 weeks; if confirmed, evaluate and manage |
| Stage 2 HTN | Evaluate and initiate treatment within 1 week |
| Hypertensive emergency | Immediate inpatient management |
Monitoring on medications:
- Electrolytes, BUN/Cr 1–2 weeks after starting ACEi/ARB or diuretic
- Echocardiogram at baseline and after 6–12 months of therapy (to assess LVH regression)
- Annual ABPM once stable
Summary Algorithm (Thai Pedia / OP Context)
Child with elevated BP reading
↓
Confirm on 3 occasions (correct technique, appropriate cuff)
↓
Classify: Elevated / Stage 1 / Stage 2
↓
History, PE, Basic Labs + Renal USS
↓
├── Age <6 yrs / Stage 2 / abnormal labs → Secondary workup
└── Age >6 yrs / Obese / FHx → Primary HTN likely
↓
Target organ assessment (Echo, fundoscopy, urine protein)
↓
├── Stage 1, no TOD → Lifestyle × 3–6 months
└── Stage 2, TOD, symptoms, DM, CKD → Pharmacotherapy + Lifestyle
↓
Goal: BP < 90th percentile (<13 yrs) or <130/80 (≥13 yrs)
Key References:
- AAP Clinical Practice Guideline: Screening and Management of High Blood Pressure in Children and Adolescents (Flynn et al., Pediatrics 2017) — the primary guideline adopted in Thai pediatric practice
- Nelson Textbook of Pediatrics, 21st Edition — Chapter on Systemic Hypertension
- Thai Pediatric Society / OP Thai Pedia standards align with AAP 2017 with local adaptations
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