Patients suspected of having primary hyperaldosteronism based on signs, symptoms, or resistant hypertension should be tested. The best screening tests to determine if a patient has primary hyperaldosteronism are simple blood tests that measure the levels of potassium, aldosterone, and renin in the blood. Patients with primary hyperaldosteronism will classically have high aldosterone levels and suppressed renin levels (i.e. very low). They will often also have low potassium levels. If the screening tests suggest primary hyperaldosteronism, then additional testing may be performed to confirm the diagnosis.