Transient hypertension can occur in a child as a result of stress, fear or pain. Blood pressure (BP) measurements repeated on several different occasions (at least three) are required to diagnose hypertension. The cuff bladder should cover at least 3/4 of the child’s arm length, and the child should be quiet and calm. In children with measured high BP, it is important to differentiate between those who have immediately dangerous hypertension and those who may have long-standing hypertension. In these patients a search for a possible underlying cause should be made. Table 9.3 shows the upper 95th centile measurements for blood pressure.
Causes of hypertension
The causes of hypertension break down into essential hypertension and secondary causes. Secondary causes fall into a few main groups, depending on the system of origin.
These include:
• Renal (75%): postinfectious glomerulonephritis, chronic glomerulonephritis, obstructive uropathy, reflux nephropathy, renovascular, hemolytic uremic syndrome, polycystic kidney disease
• Cardiovascular (15%): coarctation of the aorta
• Endocrine (5%): pheochromocytoma, hyperthyroidism, congenital adrenal hyperplasia, primary hyperaldosteronism, Cushing syndrome
• Other (5%): neuroblastoma, neurofibromatosis, steroid therapy, raised intracranial pressure.
History
The history essentially should contain details of the family history (e.g. pheochromocytoma) and of genitourinary symptoms.
The examination must include the height and weight, blood pressure measurements of both upper and lower limbs, and a full neurological examination. .
Causes of secondary hypertension
• Appearance: Cushingoid, obese
• Skin: café-au-lait spots, neurofibromas, hirsutism, vasculitis
• Fundoscopy: hypertensive retinopathy
• CVS examination: left ventricular hypertrophy, murmurs (particularly interscapular)
• Abdomen: renal/adrenal masses, renal bruits
Investigation
a. Initial investigations should include:
• urine analysis
• urine microscopy
• blood urea and electrolytes
• creatinine
b. Further investigations may include:
• urinary catecholamines
• chest X-ray
• ECG
• renal ultrasound
• gluconate scan
• plasma renin pre- and post-captopril
• thyroid function tests
• cortisol/aldosterone levels
• 17-hydroxyprogesterone
• renal angiography.
Management
a. Asymptomatic hypertension
No urgent treatment is required for asymptomatic hypertension. The child can be investigated and managed as an outpatient and should be referred to the general pediatric outpatient clinic.
b. Acute severe hypertension
These patients require admission to ICU for urgent treatment. Hypertensive encephalopathy presents as severe headache, visual disturbance and vomiting, progressing to focal neurological deficits, seizures and impaired conscious state, with grossly elevated BP, papilledema and retinal hemorrhages. These patients almost always have chronic renal disease and are on dialysis. The differential diagnosis includes uremic encephalopathy and metabolic disturbance. BP should be lowered in a controlled fashion, with anticonvulsants given for seizures.
Antihypertensives. The choice includes the drugs listed below, although this is not an exhaustive list:
• Intravenous labetalol: 0.2 mg kg−1 initially; later by i.v. infusion of labetalol 0.5–3 mg/Kg weight per hour. It should be avoided if there is heart failure, asthma or bradycardia.
• Intravenous hydralazine: 0.1 – 0.2 mg/Kg weight (max. 10 mg) stat, then 4–6 micro grams/Kg weight per minute (max 300 micrograms per min). It may cause tachycardia, nausea and fluid
retention.
• Oral captopril: 0.1 mg/Kg weight initially, increasing to a maximum of 1 mg/Kg weight (max. 50 mg). Thereafter 0.1–1.0 mg/Kg weight per dose 8-hourly. Captopril is usually effective within 30–60 minutes.
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