Introduction
Normal blood pressure in children varies according to age, gender, and height of a child. There are normal values of systolic and diastolic BP which are recorded in a large number of school children and like growth charts, percentile charts of BP are available for different ages as per the 3rd Task for blood pressure in children which is compiling data from the USA and Europe. If 3 separate BP recordings of a child are above the 95th centile for age, gender, and height it is designated as hypertension or high BP.
Causes of Hypertension
Causes of Hypertension in children in 80 - 85% of cases are due to kidney diseases like glomerulonephritis, urinary tract infections or pyelonephritis, collagen vascular diseases such as lupus erythematosus, hemolytic uremic syndrome, renal tumors like Wilm's tumor, congenital anomalies such as polycystic kidney disease or hereditary causes such as Alport's syndrome. Renal artery stenosis or aortoarteritis are renovascular causes of hypertension. Less than 5% are due to endocrinal disorders such as Cushing's or adrenal hyperplasia and adrenal tumors i.e. pheochromocytoma or neuroblastoma.
Coarctation of the aorta and patent ductus arteriosus is in less than 3% hypertensives and rare cases of meningitis, encephalitis, brain tumors are CNS causes. Less than 1 - 2% of hypertensive children are due to essential or primary hypertension in the preadolescent age group.
Symptoms of Hypertension
Symptoms of hypertension are nonspecific in young children. Irritability, excessive crying, failure to gain weight, poor feeding, low-grade fever are the only symptoms in children younger than 2 - 3 years. Later on, headache, vomiting, palpitations, giddiness, are present. In severe and acute cases, signs and symptoms of encephalopathy, cardiac failure, blindness or renal failure occur when it is called hypertensive crisis which requires hospitalization. BP recording is the only method by which hypertension is detected in children with vague symptoms.
Hypertension (High BP) - Investigations
Investigations in a case of hypertension should start with urine examination, urine culture, renal function tests, and ultrasonography of kidneys because 80 - 85% cases are due to renal diseases. Special tests like tests for SLE, hormonal assay to rule out endocrinal causes, radionuclide studies, doppler studies, and renal angiography/aortography to rule out adrenal, renovascular causes are invasive and expensive and should be done after common causes are ruled out.
Hypertensive Crisis
Hypertensive crisis is when hypertension increases to be severe enough to cause CNS, CVS, kidney or retinal involvement, and quick control of BP is required to save the child and prevent permanent damage to these organs. The aim is to lower BP to 2/3 of its peak level using rapidly acting drugs for 24 - 48 hrs like sublingual nifedipine, IV Sodium nitroprusside, IV Labetalol, or hydralazine. Subsequently, oral medications can be used to bring BP to normal levels by 1 - 3 weeks. The very rapid reduction can result in poor perfusion of the brain, coronary arteries, kidney, etc. Simultaneously investigations, to arrive at the cause of hypertension should be started so that treatment can be offered.
Hypertension (High BP) - Treatment
Treatment of hypertension is urgently required to control BP in hypertensive emergencies to prevent damage to the brain, heart, kidney, and retina.
In cases with chronic hypertension which is moderate or severe, oral medicines are used depending on the cause. Diuretics are used in renal diseases with sodium and water retention. b blockers and vasodilators like propranolol, hydralazine, and recently even calcium channel blockers (nifedipine) and ACE inhibitors (enalapril) are used if hypertension is not controlled by diuretics, b blocker/vasodilator combinations. Initially, a single drug should be used and the dose increased every 1 - 3 weeks and if after 2 - 3 weeks BP is still above the 50th centile, the new drug is added. Chronic hypertension may require treatment for years.
Mild to moderate hypertension with minimum symptoms may be controlled by nonpharmacologic measures like weight reduction in obese children, diet control (low salt, high potassium, high calcium & magnesium, and low-fat diet), exercises - yoga, lifestyle modification, reduction of stress, etc.
Hypertension (High BP) - Complications
Long term complications of hypertension are cerebrovascular stroke, cardiovascular damage resulting in left ventricular dysfunction/failure, renal failure, and retinopathy or blindness.