Aldosterone and renin

aldosterone renin ratio · ARR · renin test · aldosterone test

This blood test checks two substances that control blood pressure and salt in your body.

When blood pressure is high and hard to bring down with medicines, when potassium in your blood is low, or when something was found in an adrenal gland.

⏱ Duration: the blood draw takes a few minutes; results usually come in a few days

Be sure to tell your doctor

All blood pressure medicines and water pills. Many of them change the result
If you take hormonal birth control
If your potassium was low in past tests
If you eat a lot of licorice or drink drinks that contain it

How to prepare

Medicines. Many blood pressure pills affect this test. Your doctor may switch them ahead of time. Do not stop anything on your own.
Salt. Eat as usual. Do not cut down on salt on purpose unless the doctor says so.
Morning. Blood is usually taken in the morning after you have been up and about for around two hours. Then you sit for a few minutes. Check with the lab.
Clothing. A sleeve you can easily roll up above the elbow.

What to bring

Your referral or list of tests
Your ID
A list of all your medicines and doses
Your latest potassium results

How it goes

You sit quietly for a few minutes before the draw
A band is tied above your elbow, and you are asked to clench your fist a few times
The skin is wiped with antiseptic
A quick prick. Blood fills the tubes in a few seconds
The needle comes out, and a cotton pad is pressed on the spot

What you'll feel

A quick prick, like a pinch
Sometimes slight dizziness. Tell the nurse, and they will help you lie down

Afterwards

Press the cotton pad for 3 to 5 minutes
Take your medicines as your doctor told you
The doctor will review the result. Sometimes more tests are needed

Contact a doctor straight away if

The puncture site is very swollen, painful, and red
Severe headache, blood pressure much higher than usual, or weakness in an arm or leg: call emergency services

Common questions

Why is my doctor changing my pills before the test?

Some blood pressure medicines distort the result. The switch is only for the time of the tests.

What if my blood pressure goes up after the switch?

Do not go back to your old medicines on your own. Call your doctor and keep checking your blood pressure.