In evaluating a hypertensive child, it is important for clinicians to utilize proper tools to measure and interpret the blood pressure (BP) readings. The preferred method of BP measurement is auscultation using a mercury sphygmomanometer connected to the appropriate size cuff. Systolic blood pressure (SBP) is determined by the onset of the "tapping" Korotkoff sounds (K1) while diastolic blood pressure (DBP) is defined as the fifth Korotkoff sound (K5), or the disappearance of Korotkoff sounds. Use of the automated devices can be used for BP measurement in newborns and young infants, in whom auscultation is difficult. An elevated BP reading obtained with an oscillometric device should be repeated with auscultation. To determine percentile of blood pressure, the values are compared to normal blood pressure in children and adults adjusted for age, sex and height. Hypertension is defined as average SBP and/or DBP that is ≥95th percentile for gender, age, and height on ≥3 occasions. Elevated BP must be confirmed on repeated visits before characterizing a child as having hypertension. (1)

Blood pressure is regulated through the interaction of intravascular volume, cardiac output and peripheral resistance. Steroid hormones are involved in blood pressure regulation by affecting any or all of these parameters. Glucocorticoids directly accentuate the response of vascular smooth muscle to pressor agents via glucocorticoid receptors to increase vascular tone. Cortisol also binds to the type I mineralocorticoid receptor (MR), thereby increasing sodium reabsorption. Mineralocorticoids primarily act via the MR to promote sodium reabsorption, with subsequent water retention and intravascular volume expansion. These hemodynamic changes then affect peripheral resistance and cardiac output, which in turn influence blood pressure. Cortisol is the main product of the middle zona fasciculata (ZF) in the adrenal cortex (Figure 1) and is under direct control of adrenocorticotropin hormone (ACTH).

Cortisol is the main product of the middle zona fasciculata (ZF) in the adrenal cortex (Figure 1) and is under direct control of adrenocorticotropin hormone (ACTH).

The production of aldosterone by the zona glomerulosa (ZG) is principally modulated by the renin-angiotensin system and serum potassium (Figures 2a, 2b). Minor regulators include ACTH from the pituitary gland, atrial natriuretic factor from the heart, and dopamine secreted locally in the adrenal. Because aldosterone enhances the reabsorption of sodium, there is an osmotic reabsorption of water through sodium-permeable channels in the apical membranes of the epithelial cells lining the distal tubules and collecting ducts in the kidney. This results in an expanded blood volume and suppression of renin secretion. Aldosterone also increases potassium excretion. Endocrine hypertension in children is usually mediated by the mineralocorticoid activities of cortisol and aldosterone as well as their adrenal steroidogenic precursors with mineralocorticoid activity. This chapter describes the most common causes of endocrine hypertension in children and some conditions with similar presentation.