An Aldosterone (AUS) test is a medical test to measure the level of the hormone aldosterone, primarily to screen for and diagnose conditions like primary aldosteronism. The “AUS” likely refers to it being a test performed in Australia, where a common confirmatory test is a saline infusion test done in a hospital setting to see if the body continues to produce too much aldosterone despite having an excess of salt. The initial screening test for primary aldosteronism is often an aldosterone-to-renin ratio (ARR) blood test, and further confirmatory tests, like the saline infusion test, are used to diagnose the condition