An Aldosterone Diagnostic Test measures the level of aldosterone, a hormone produced by the adrenal glands that plays a critical role in regulating blood pressure. It controls how the kidneys balance essential electrolytes, specifically by retaining sodium and excreting potassium.

Clinicians typically order this blood or 24-hour urine test to investigate primary aldosteronism (Conn's syndrome), unexplained high blood pressure, or low blood potassium levels. Because aldosterone levels fluctuate based on salt intake and body position, the test is frequently performed alongside a plasma renin activity (PRA) test to accurately evaluate underlying adrenal or kidney disorders.