A pheochromocytoma is a tumor arising from chromaffin cells that secretes excess catecholamines (norepinephrine, epinephrine, or both). It is one endocrine cause of hypeension, due to peripheral vasoconstriction and/or increased cardiac output. While most patients have higher than normal baseline plasma levels of catecholamines, it is not uncommon for paroxysmal symptomatic episodes to be superimposed upon the basal problem. These "attacks" may occur several times a week (or more often) and last for up to 15 minutes. During an attack, respiration can increase, the patient may become aware of a forceful pounding of the hea that progresses to include a throbbing headache, and peripheral vasoconstriction can raise body temperature and lead to reflex sweating. Marked anxiety may also accompany the episode. Diagnosis can be confirmed by measuring increased plasma or urinary catecholamines or their metabolites. 11-beta-hydroxylase deficiency is a congenital disorder than can cause hypeension due to excessive production of the weak mineralocoicoid, deoxycoicosterone, by the inner two zones of the adrenal coex. This results in excessive renal retention of sodium and water and subsequent hypeension. While the hypeension is usually present from bih, a late-onset variant of this disorder has been described in which the symptoms do not present until late childhood or adolescence. Virilization is also present due to excessive secretion of adrenal androgens. Conn's syndrome is another endocrine cause of hypeension. In this case, the increase in blood pressure is due to excessive renal retention of sodium and water resulting from the increased plasma concentration of aldosterone. The paroxysmal symptoms and increased catecholamines present in this patient are not present with primary hyperaldosteronism. Renin-secreting tumors are rare and can be confused with primary hyperaldosteronism. The excessive secretion of renin by the tumor can increase the formation of angiotensin II with subsequent hyperaldosteronism. Sodium and water retention, together with hypokalemia, are present. Increased plasma renin and plasma aldosterone are suggestive of a renin-secreting tumor, whereas primary hyperaldosteronism would present as increased plasma aldosterone, but decreased plasma renin. Ref: Lal G., Clark O.H. (2010). Chapter 38. Thyroid, Parathyroid, and Adrenal. In F.C. Brunicardi, D.K. Andersen, T.R. Billiar, D.L. Dunn, J.G. Hunter, J.B. Matthews, R.E. Pollock (Eds), Schwaz's Principles of Surgery, 9e.