Test Details & Preparation

• Aldosterone and renin tests are used to evaluate whether the adrenal glands are producing appropriate amounts of aldosterone and to distinguish between the potential causes of excess or deficiency.


• Aldosterone and renin tests are useful in testing for primary aldosteronism, also known as Conn syndrome, which causes high blood pressure.


• A blood aldosterone test and a renin test are usually ordered together when someone has high blood pressure, especially if the person also has low potassium. Even if potassium is normal, testing may be done if typical medications do not control the high blood pressure or if hypertension develops at an early age.


• A blood sample is taken by needle from a vein in the arm to measure blood aldosterone and/or renin. Some doctors prefer 24-hour urine collection for aldosterone since blood aldosterone levels vary throughout the day and are affected by position. In some cases, blood is collected from the renal (for renin) or adrenal (for aldosterone) veins by insertion of a catheter.


• For a blood aldosterone and renin test, the doctor may ask you to be upright or lying down for a period of time (e.g., 15-30 minutes) prior to sample collection. You may also be instructed to avoid certain beverages, foods, or medications before the test.


• Primary aldosteronism (Conn syndrome) is caused by the overproduction of aldosterone by the adrenal glands, usually by a benign tumour of one of the glands. The high aldosterone level increases re-absorption of sodium (salt) and loss of potassium by the kidneys, often resulting in an electrolyte imbalance.


• Secondary aldosteronism, which is more common than primary aldosteronism, is caused by anything that leads to excess aldosterone, other than a disorder of the adrenal glands.


• Low aldosterone (hypoaldosteronism) usually occurs as part of adrenal insufficiency it causes dehydration, low blood pressure, a low blood sodium level, and a high potassium level.