Hypertension and Renovascular Disease
Core concepts
Pediatric hypertension is defined using age-, sex-, and height-specific percentiles; values at or above the 95th percentile on repeated measurements require evaluation, and severe hypertension with end-organ symptoms is an emergency. Primary hypertension is more common in older adolescents with obesity and family history. Secondary hypertension is more likely in younger children, especially with renal parenchymal disease, renovascular stenosis, coarctation of the aorta, or endocrine causes. Renovascular disease may occur with fibromuscular dysplasia, neurofibromatosis, Williams syndrome, or umbilical artery catheterization in neonates. Suspect it when hypertension is severe, associated with hypokalemia, elevated renin, asymmetric kidney size, or poor response to therapy.
Traps
Do not rely on a single office reading; confirm with repeated measurements or ambulatory blood pressure monitoring. Four-limb blood pressures help detect coarctation. Renal ultrasound is a reasonable first imaging test but may miss renovascular disease; magnetic resonance angiography or captopril renography may be needed. ACE inhibitors and ARBs are effective in renovascular hypertension but are risky in bilateral renal artery stenosis or a solitary kidney because they can precipitate AKI. In hypertensive emergency, lower blood pressure gradually: aim for no more than a 25% reduction in the first 8 hours to avoid cerebral, optic, or myocardial ischemia.
Worked example / rule of thumb
An adolescent with severe hypertension, hypokalemia, high plasma renin, and a small right kidney on ultrasound likely has renovascular hypertension. Obtain vascular imaging and avoid ACE inhibitor monotherapy until bilateral disease is excluded. Rule: emergency = severe blood pressure plus encephalopathy, seizures, visual changes, heart failure, or renal injury; use titratable intravenous agents such as nicardipine, labetalol, or nitroprusside.