The Aldosterone-to-Renin Ratio (ARR) test measures the levels of aldosterone (a hormone produced by the adrenal glands) and plasma renin activity (an enzyme released by the kidneys) in the blood. By calculating the ratio between these two, the test helps evaluate how well the adrenal glands and kidneys are regulating blood pressure and electrolyte balance.
A high ARR often points to primary aldosteronism (also called Conn’s syndrome), a treatable condition in which the adrenal glands produce too much aldosterone independently of renin. This is one of the most common curable causes of secondary hypertension.
Doctors typically order this test for patients with:
- Resistant or difficult-to-control high blood pressure
- Low blood potassium (hypokalemia)
- Suspicion of an adrenal disorder
Results can confirm primary aldosteronism, guide further confirmatory testing, and inform treatment decisions (such as medication or surgery). Early diagnosis and management can significantly lower the risk of heart disease, stroke, and other complications linked to long-term uncontrolled hypertension.
