Hypertension
The prevalence of hypertension in childhood is low (1% to 3%), and the majority of affected children have only mild elevations of blood pressure (BP), which are thought to be early manifestations of primary hypertension. A minority of hypertensive children (about 10%) have more marked elevations in BP, and these individuals often have secondary hypertension. Of those children who have a definable cause for their hypertension, 80% to 90% have renal or renovascular disease as an underlying cause. Therefore, the strategy for evaluating a child for secondary causes of hypertension generally is aimed at finding renal or renovascular disease as well as less common causes. The major conditions associated with sustained hypertension are listed in Table 1; causes of acute hypertension are listed in Table 2.
Measuring Blood Pressure
A number of children who do not actually have hypertension exhibit "high" BP upon the initial examination. Many of these children are large for their chronologic age, and usually their BP has been measured with an inappropriately small cuff. Falsely elevated pressures may be obtained with a cuff that is too small, but falsely positive low BP is rare, even if the cuff is too large. When used on an upper extremity, the BP cuff should cover at least two thirds of the upper arm; the internal bladder should encircle at least 80% of the arm circumference to avoid inaccurately high readings.
Renovascular disease: a common cause of secondary hypertension
