Hypersecretion of aldosterone by the adrenal cor-tex (primary aldosteronism) can be due to a unilat-eral adenoma (aldosteronoma or Conn syndrome), bilateral hyperplasia, or in very rare cases carcinoma of the adrenal gland. Some disease states stimu-late aldosterone secretion by affecting the renin– angiotensin system. For example, congestive heart failure, hepatic cirrhosis with ascites, nephrotic syn-drome, and some forms of hypertension (eg, renal artery stenosis) can cause secondary aldosteronism. Although both primary and secondary aldosteron-ism are characterized by increased levels of aldo-sterone, only the latter is associated with increased renin activity. The usual clinical manifestations of mineralocorticoid excess include hypokalemia and hypertension, and an increased ratio of aldosterone– plasma renin activity has been noted in laboratory studies.
Fluid and electrolyte disturbances can be corrected preoperatively using spironolactone. This aldoste-rone antagonist is a potassium-sparing diuretic with antihypertensive properties. Intravascular volume can be assessed preoperatively by testing for ortho-static hypotension.