Aldosterone/renin ratio (ARR) is a screening test to detect primary aldosteronism in high-risk, hypertensive individuals.
To determine the ratio, blood levels of aldosterone and renin are measured and a calculation is done by dividing the aldosterone result by the renin result.
The ARR is considered the most reliable screening for primary aldosteronism, though it is not straightforward to interpret.
Anything that could interfere with the test, such as medications, posture, sodium intake, and plasma potassium, needs to be taken into account before the test to avoid false positives or false negatives.
Other tests, like suppression tests, are used to confirm the diagnosis after screening.