Aldosterone Test

What is an aldosterone (ALD) test?

An aldosterone test measures the amount of aldosterone (ALD) in your blood or urine (pee). ALD is a hormone made by your adrenal glands, two small glands that sit above your kidneys. ALD helps keep your blood pressure stable by helping to balance the levels of two electrolytes in your blood, sodium and potassium.

Sodium helps your body keep more water in your bloodstream, which makes your blood pressure increase. Potassium, however, lowers your blood pressure by helping your blood vessels relax and your kidneys get rid of excess sodium. So, if your blood pressure gets too low, ALD signals your kidneys to release more sodium into your blood and to get rid of potassium through urine. This then raises your blood pressure. When your blood pressure returns to normal, your ALD levels decrease.

If your ALD levels are too high or too low, your blood pressure may also be too high or too low. This can cause serious health conditions. Abnormal ALD levels can also cause you to have abnormal levels of sodium and potassium, which can affect your heart, kidneys, and other parts of your body.

An ALD test is commonly combined with a test that measures renin levels in your blood. This is called an aldosterone-renin ratio test. Renin is a hormone that your kidneys make when your blood pressure gets too low. It’s part of a complex system that triggers your adrenal glands to make ALD.

Other names: aldosterone, serum; aldosterone urine; aldosterone-renin ratio test; aldosterone-plasma renin activity

What is it used for?

ALD testing is mainly used with renin testing to diagnose two types of adrenal gland disorders, which can cause abnormal ALD levels. These are:

• Primary aldosteronism (also called Conn syndrome), which is usually caused by a benign (not cancerous) tumor on an adrenal gland. This tumor produces extra ALD.
• Adrenal insufficiency (also called Addison disease), which usually happens when your adrenal glands have been damaged, causing them to produce lower levels of ALD. This damage may be caused by conditions such as an immune disorder (the most common cause), certain infections, and cancer cells in the adrenal glands. To diagnose Addison disease, your provider may use additional tests.

ALD testing can also help:

• Find the cause of abnormal sodium or potassium levels on an electrolyte test
• Discover the cause of orthostatic hypotension (a sudden drop in blood pressure that makes you dizzy when you get up from sitting or lying down)

ALD and renin testing can also help determine whether your kidneys are affecting your blood pressure. If your ALD levels are within a healthy range, it could mean that your renin levels are too high or too low.

Why do I need an aldosterone test?

You may need this test if you have signs or symptoms of high or low aldosterone (ALD) levels or high blood pressure that:

• Happens with low potassium levels
• Doesn't improve with usual blood pressure medicines
• Develops at a young age

Symptoms of too much ALD (called hyperaldosteronism or aldosteronism) include:

• High blood pressure
• Low potassium test results and/or high sodium test results
• Muscle weakness, cramps, and/or spasms
• Fatigue
• Headache
• Arrhythmia (a problem with the rate or rhythm of your heartbeat)
• Increased thirst and urination

Symptoms of too little ALD (called hypoaldosteronism) include:

• Low blood pressure
• Test results that show high potassium and/or low sodium levels
• Fatigue
• Muscle weakness
• Loss of appetite
• Weight loss
• Abdominal (belly) pain

What happens during an aldosterone test?

An aldosterone (ALD) test uses a sample of blood or urine. A test that compares your ALD and renin levels uses a blood sample.

During a blood test, a health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

The amount of ALD in your blood changes depending on whether you are standing up or lying down. So, you may be asked to lie down or stand for a period of time before the test. You may also be tested in both positions.

For an ALD urine test, your provider may ask you to collect all urine during a 24-hour period. You will be given a special container to collect your urine and instructions on how to collect and store your samples. Your provider will tell you what time to start. The test generally includes the following steps:

• Urinate (pee) in the toilet as usual. Do not collect this urine. Write down the time you urinated.
• For the next 24 hours, collect all your urine in the container.
• During the collection period, store the urine container in a refrigerator or cooler with ice.
• 24 hours after starting the test, try to urinate if you can. This is the last urine collection for the test.
• Return the container with your urine to your provider's office or the laboratory as instructed.

Will I need to do anything to prepare for the test?

Follow the instructions your provider gives you. You may need to stop taking certain medicines for a period of time before the test. This includes certain over-the-counter medicines. So, be sure to tell your provider everything you're taking. But don't stop taking any prescribed medicine unless your provider tells you to stop.

You may also be asked to limit the amount of salt you eat each day for about two weeks before your test. Your provider will explain how to limit salt in your diet.

You should not eat natural black licorice for at least two weeks before your test, because it can affect your results. Most licorice products in the United States don't contain natural licorice. But if you eat licorice, check the ingredients label to be sure.

Are there any risks to the test?

There is very little risk to having a blood test. You may experience slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

There are no known risks to having a urine test.

What do the results mean?

To understand what your test results mean, your provider will consider your aldosterone (ALD) levels along with the results of other tests. Ask your provider to explain what your results say about your health.

In general, higher than normal amounts of ALD may mean you have primary or secondary aldosteronism. With primary aldosteronism, a benign tumor on your adrenal gland makes extra ALD. With secondary aldosteronism, your adrenal glands are healthy, but another medical condition is causing them to make too much ALD.

Conditions that can cause high ALD levels include:

• Kidney disease
• Cirrhosis of the liver
• Heart failure
• Preeclampsia, a type of high blood pressure that happens in pregnancy
• Dehydration

In general, lower than normal amounts of ALD may mean you have:

• Addison disease (also called adrenal insufficiency).
• Congenital adrenal hyperplasia (CAH), a group of genetic disorders you're born with.
• Secondary adrenal insufficiency, a condition that starts with a problem in your pituitary, a gland at the base of your brain that controls your adrenal glands.
• Tertiary adrenal insufficiency, a condition caused by a problem in your hypothalamus, a gland that tells your pituitary when to signal your adrenal glands to make hormones. The most common cause is suddenly stopping steroid medicines after taking them for a long time. Steroids can cause hormonal changes that make your adrenal glands shut down. When you stop taking the steroids, your adrenal glands may be slow to start working again.

Low levels of ALD may also be linked to:

• Certain other health conditions, such as diabetes and lead poisoning
• Certain medicines, including non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, and some heart failure medicines

If you have questions about your results and treatment options, talk with your provider.

Learn more about laboratory tests, reference ranges, and understanding results.