Aldosterone

The Aldosterone test (adrenal cortex hormone; mineralocorticoid) is used to assess whether aldosterone production is appropriate and to investigate causes of excess or deficiency. It is a key component of screening for primary hyperaldosteronism (Conn syndrome) and for distinguishing primary from secondary hyperaldosteronism, typically alongside plasma renin with calculation of the aldosterone–renin ratio. This assay also supports evaluation of resistant hypertension or hypertension with early onset and contributes to the assessment of suspected adrenal insufficiency or hypoaldosteronism.

Aldosterone regulates extracellular sodium and potassium balance and thereby influences intravascular volume and arterial pressure. Secretion increases in response to angiotensin II generated via renin when blood pressure or sodium levels fall, and it is suppressed when intravascular volume or dietary sodium is elevated. Interpretation is typically integrated with renin measurement: primary hyperaldosteronism features elevated aldosterone with suppressed renin; secondary hyperaldosteronism shows increased aldosterone with high renin; adrenal insufficiency (Addison disease) demonstrates low aldosterone with elevated renin.