Aldosterone-renin ratio (ARR), plasma renin activity (PRA), plasma aldosterone
This test measures levels of the hormones aldosterone and renin in your blood.
Aldosterone and renin play important roles in the body. Aldosterone regulates your levels of potassium, sodium, and overall blood volume. High levels of aldosterone can lead to a condition called primary aldosteronism (PA), which causes high blood pressure. PA can then lead to a variety of other health conditions.
A high level of aldosterone typically causes a dip in renin level. The aldosterone and renin test looks at the ratio between these two hormones to help your doctor make a diagnosis.
You may need this test if your health care provider suspects that you have a high aldosterone level or PA. Besides high blood pressure, high aldosterone levels can damage your heart and vascular system as well as your brain and kidneys.
You may also have frequent blood pressure tests if you're at risk for PA. Your health care provider may do other blood tests to find the cause of high blood pressure or confirm the PA diagnosis.
Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.
In general, a high level of aldosterone and a low level of renin mean it's likely you have primary aldosteronism.
The test requires a blood sample, which is drawn through a needle from a vein in your arm.
Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.
A number of factors can affect your levels of aldosterone and renin. These include:
Time of day the test is done
Activity level during the day
Sodium (salt) intake
Aldosterone levels are highest in the morning, so you may need to have the test in the morning after you've been awake and moving around for about two hours.
Ask your health care provider if you have any food restrictions and if you need to stop taking your medication before the test. Be sure your doctor knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.