Hypertension in Children
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Direct answer
Blood pressure above the 95th percentile for age, sex and height on three separate occasions defines hypertension in a child, and unlike adults, childhood hypertension is usually secondary — renal parenchymal disease tops the list, with coarctation of the aorta, renovascular disease and endocrine causes behind it. Measure in the right arm with the correct cuff (bladder width about 40 per cent of the arm's circumference), confirm every abnormal reading, and check four-limb pressures in every hypertensive child to catch coarctation. Emergencies are brought down by no more than about a quarter in the first eight hours, because abrupt normalisation in a chronically vasoconstricted child risks neurological damage.
What you must remember
- Thresholds: average systolic and/or diastolic BP at or above the 95th percentile for sex, age and height on three visits; elevated BP sits between the 90th percentile (or 120/80 in adolescents) and the 95th.
- Stage 1 hypertension spans the 95th percentile up to 95th percentile plus 12 mmHg; stage 2 is beyond that — stage 2 or symptomatic hypertension deserves prompt evaluation.
- Technique: cuff bladder width 40 per cent of arm circumference and length 80–100 per cent; too small a cuff overestimates BP — the commonest cause of spurious "hypertension" in clinics.
- Cause ladder: renal parenchymal disease (glomerulonephritis, reflux nephropathy, polycystic disease) is the largest group; then renovascular (fibromuscular dysplasia), coarctation, endocrine (neuroblastoma, phaeochromocytoma, steroid excess), and monogenic forms such as Liddle syndrome.
- Essential hypertension clusters in overweight adolescents with family history and is a diagnosis of exclusion under ten years.
- Every hypertensive child needs four-limb blood pressures and femoral pulse palpation: upper-limb hypertension with delayed, weak femoral pulses means coarctation.
- Minimum work-up: urinalysis, electrolytes, creatinine, renal ultrasound with Doppler, and echocardiography — the last identifies coarctation and documents left ventricular hypertrophy as target-organ damage.
- Screen metanephrines for the triad of headache, sweating and palpitations; renin and aldosterone studies when hypokalaemic alkalosis appears.
- Chronic therapy: angiotensin-converting-enzyme inhibitors (especially with proteinuric renal disease or diabetes), calcium channel blockers such as amlodipine, beta-blockers and thiazides; start one drug low and titrate.
- Emergency drugs: intravenous labetalol or nicardipine infusion; avoid precipitous falls — reduce the pressure by no more than about 25 per cent over the first eight hours.
A typical exam case
A seven-year-old admitted with a convulsion is found to have a blood pressure of 170/115 mmHg. First ask what the percentile is: this is far beyond stage 2 for her age and size, and the seizure makes it a hypertensive emergency. Stabilise airway and seizure control, then bring pressure down deliberately — intravenous labetalol or nicardipine with intra-arterial or frequent non-invasive monitoring, targeting roughly a quarter reduction over the first eight hours. Meanwhile, the cause is being narrowed in parallel: urinalysis showing dysmorphic red cells and protein, with scarred kidneys on ultrasound and a reflux history, diagnoses reflux nephropathy as the driver.
Contrast the asymptomatic eleven-year-old with BP at the 97th percentile on three school screenings, BMI well above the 95th centile, a father on antihypertensives, normal urine and biochemistry, and left ventricular geometry at the upper limit. That child has primary (essential) hypertension: management begins with weight reduction, salt limitation, aerobic activity and a structured follow-up, escalating to amlodipine or an ACE inhibitor only if targets are not met over months. The third child is the boy with arm hypertension, absent femoral pulses and a systolic gradient between arms and legs — coarctation, treated surgically or by catheter; checking the legs was the whole question.
How the exam frames it
Questions concentrate on measurement method, secondary-cause logic and emergencies. A one-best-answer may show a clearly too-narrow cuff and ask why the reading is high — overestimation. Another asks the first investigation in a young severely hypertensive child: urine examination and renal imaging before endocrine panels. Stems with headache-sweating-palpitations point to catecholamine excess; a murmur between the scapulae points to coarctation. And the negative-marking favourite: how fast to lower BP in hypertensive encephalopathy — candidates who write "rapidly normalise" fail, because rapid correction provokes ischaemia of a chronically autoregulated brain.
Frequently asked questions
How is hypertension defined and staged in children?
As average systolic or diastolic pressure at or above the 95th percentile for age, sex and height on three separate occasions; stage 1 extends to the 95th percentile plus 12 mmHg, stage 2 beyond.
What is the commonest cause of hypertension in a young child?
Secondary renal disease — parenchymal disorders such as glomerulonephritis, reflux nephropathy or cystic disease — whereas essential hypertension grows likelier in overweight adolescents.
Why measure blood pressure in all four limbs?
To exclude coarctation of the aorta, which produces hypertension in the upper limbs with lower pressures and delayed or absent femoral pulses in the legs; it is mandatory in every hypertensive child.
Which drug classes are preferred for chronic paediatric hypertension?
ACE inhibitors (particularly with renal disease, proteinuria or diabetes), calcium channel blockers such as amlodipine, beta-blockers and thiazides, chosen for comorbidity and titrated as monotherapy first.