Pediatric Hypertension Workup

Updated: Mar 09, 2017
  • Author: Edwin Rodriguez-Cruz, MD; Chief Editor: Syamasundar Rao Patnana, MD  more...
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Workup

Laboratory Studies

In patients with hypertension, proceed from simple tests that can be performed in an ambulatory setting to complex noninvasive tests and finally to invasive tests. Findings from the patient’s history and physical examination dictate the appropriate choice of tests.

The complete blood cell (CBC) count may indicate anemia due to chronic renal disease. Blood chemistry studies may be helpful. An increased serum creatinine concentration indicates renal disease. Hypokalemia suggests hyperaldosteronism (see potassium).

Blood hormone levels may be measured. High plasma renin activity indicates renal vascular hypertension, including coarctation of the aorta, whereas low activity indicates glucocorticoid-remediable aldosteronism, Liddle syndrome, or apparent mineralocorticoid excess. A high plasma aldosterone concentration is diagnostic of hyperaldosteronism. High values of catecholamines (eg, epinephrine, norepinephrine, or dopamine) are diagnostic of pheochromocytoma or neuroblastoma.

On urine dipstick testing (see urinalysis), a positive result for blood or protein indicates renal disease. Urine cultures are used to evaluate the patient for chronic pyelonephritis. High urinary excretion of catecholamines and catecholamine metabolites (metanephrine) indicates pheochromocytoma or neuroblastoma. Urine sodium levels reflect dietary sodium intake and may be used as a marker to follow a patient after dietary changes are attempted.

Fasting lipid panels and oral glucose-tolerance tests are performed to evaluate metabolic syndrome in obese children. Drug screening is performed to identify substances that might cause hypertension.

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Echocardiography and Ultrasonography

Left ventricular hypertrophy (LVH) results from chronic hypertension. The finding of LVH on echocardiography confirms the chronicity of the hypertension and is an absolute indication for starting or intensifying treatment. LVH is symmetric, consisting of equivalent increases in in thickness for both the left ventricular portion of the ventricular septum and the left ventricular posterior wall. Left ventricular function must also be assessed.

Echocardiography is essential in the evaluation of suspected aortic coarctation. The aortic arch and its branches must be examined in precise anatomic detail. Doppler sonographic interrogation of the aortic arch should include pulse Doppler sampling from various portions of the aortic arch and continuous wave Doppler of the descending aorta. These data are useful in quantitating the severity of aortic obstruction. [18]

Abdominal ultrasonography may reveal tumors or structural anomalies of the kidneys or renal vasculature. Renal scarring suggests excessive renin release. Asymmetry in renal size suggests renal dysplasia or renal artery stenosis. Renal or extrarenal masses suggest a Wilms tumor or neuroblastoma, respectively.

On Doppler studies, asymmetry in renal artery blood flow suggests renal artery stenosis.

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Angiography

Angiography may reveal differences in the structure (diameter) of the renal vessels. Sampling of blood from renal arteries, renal veins, and aorta may reveal differences in renin secretion between the kidneys. A renin activity ratio of 3:1 between the kidneys is considered diagnostic of renal vascular hypertension.

On digital subtraction arteriography, asymmetry between the 2 renal arteries indicates renal artery stenosis.

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24-Hour Ambulatory Blood Pressure Monitoring (ABPM)

Ambulatory blood pressure monitoring (ABPM) displays blood pressure (BP) changes associated with physiologic activity and environmental stimuli during sleep as well as while awake, and it may serve to better assess the BP. The mean 24-hour BP (systolic and diastolic) are compared with gender- and height-specific 99th percentiles based data. ABPM is useful in the initial evaluation of elevated BP, to recognize subjects at risk, and in evaluating response to treatment. [13]

Monitoring of BP on a 24-hour basis may help in diagnosing so-called white-coat hypertension and provides information about the risk of target end-organ damage. White-coat hypertension is common because most children are uncomfortable at the physicians’ office, fearing invasive examinations, vaccinations, blood draws, and other factors. Use of 24-hour BP monitoring should be considered first in most uncomplicated cases of pediatric stage I hypertension.

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Other Tests

Cardiac catheterization is not necessary in the evaluation of aortic coarctation. However, it is an integral part of transcatheter interventions such as balloon angioplasty or stent therapy. [19]

Computed tomography (CT) and magnetic resonance imaging (MRI) with angiography can provide further anatomic definition of an aortic coarctation, but neither study is necessary for diagnosis.

Radionuclide imaging may be considered, with or without captopril; asymmetry suggests renal artery stenosis.

Polysomnography helps in identifying sleep disorders associated with hypertension. This test should be considered in obese children with a history of snoring, daytime sleepiness, or any sleep difficulties.

Retinal examination may reveal retinal vascular changes.

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