Cushing's syndrome, which is rare in childhood, is caused by ACTH hypersecretion from a pituitary microadenoma, i.e. Cushing's disease, in the majority of cases. In two series of pediatric patients with Cushing's syndrome, hypertension was present in 47% and 75% of patients. (47, 48) Aldosterone and renin levels are usually normal (49, 50) and DOC levels are normal or minimally increased in Cushing's disease. (51) The elevation of blood pressure due to hypercortisolemia is mediated by multiple mechanisms; the most important being increased cardiac output (52) and activation of the renin-angiotensin system by increased hepatic production of angiotensinogen. (50)

Liddle’s syndrome is a rare autosomal dominant disease described by Liddle et al. in 1963 (53) causing arterial hypertension. Mutations in SCNN1B and SCNN1G, the genes that mapped to chromosome 16p12, have been described in Liddle’s syndrome patients. (3) The clinical and biochemical findings other than elevated blood pressure are chronic hypokalemia, increased urinary potassium excretion in conjunction with sodium retention, suppressed renin activity, aldosterone and angiotensin II. These presentations are similar to AME, but in contrast, Liddle’s syndrome is an autosomal dominant disorder that does not show a favorable response to spironolactone. (10)

Primary glucocorticoid resistance is another rare disorder, with autosomal recessive or dominant inheritance that is caused by inactivating mutations of the glucocorticoid receptor gene. (54) There is compensatory elevation of cortisol and ACTH in the absence of clinical features of Cushing's syndrome. Hypertension results from the action of cortisol on the MR receptor, as well as ACTH hyperstimulation of adrenal steroidogenic precursors with mineralocorticoid activity, such as compounds B and S.

Hypertension is associated with both hyperthyroidism and hypothyroidism. Hyperthyroidism can cause systolic hypertension due to tachycardia, increased cardiac output, increased stroke volume and decreased peripheral vascular resistance. (55, 56) Hypothyroidism results in diastolic hypertension, thought to be secondary to extracellular volume expansion and elevation in systemic vascular resistance.

Approximately one-third of patients with hyperparathyroidism have been reported to be hypertensive. The mechanisms are unclear and may not remit following successful parathyroidectomy.

Acknowledgment-The authors wish to express their appreciation to Brian Betensky for his editorial assistance in the preparation of this chapter.