Primary aldosteronism, also known as primary hyperaldosteronism, is characterized by the overproduction of the mineralocorticoid hormone aldosterone by the adrenal glands, when not a result of excessive renin secretion. Aldosterone causes increase in sodium and water retention and potassium excretion in the kidneys, leading to arterial hypertension (high blood pressure). An increase in the production of mineralocorticoid from the adrenal gland is evident. It is amongst the most common causes of secondary hypertension, renal disease being the most common.
Primary hyperaldosteronism has many causes, including adrenal hyperplasia and adrenal carcinoma. When it occurs due to a solitary aldosterone-secreting adrenal adenoma (a type of benign tumor), it is known as Conn's syndrome. In practice, however, the terms are often used interchangeably, regardless of the underlying physiology.