Definition

Conn’s syndrome, the most common form of primary aldosteronism, results from hypersecretion of aldosterone from an adrenal adenoma independent of stimulus.

Pathophysiology

Primary aldosteronism may also be caused by adrenocortical hyperplasia or rarely carcinoma. An increase in the plasma concentration of aldosterone and an increase in the urinary excretion of potassium with coexisting hypokalemia are pathognomonic of hyperaldosteronism.

Manifestations of the syndrome reflect the exaggerated effects of al-dosterone. Diastolic hypertension and hypernatremia are usually present. Aldosterone’s action of promoting renal excretion of K⁺ (or H⁺) in exchange for Na⁺ results in hypokalemic metabolic alkalosis. Hypertension associated with Conn’s syndrome results from aldosterone-induced sodium retention and subsequent increase in extracellular fluid volume. Primary aldosteronism accounts for approximately 1% of all cases of hypertension.

Primary aldosteronism is associated with low renin levels, a result of the elevated blood pressure’s negative feedback to the juxtaglomerular cells. With secondary hyperaldosteronism, the stimulus of excess aldosterone resides outside of the adrenal gland and is often associated with an increase in circulating renin levels.