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. It does this by helping to balance the levels of two electrolytes in your blood, sodium and potassium.
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 helps keep more water in your bloodstream, which makes your blood pressure increase. When your blood pressure returns to normal, your ALD levels decrease.
Abnormal ALD levels can cause serious health conditions, including:
- High blood pressure
- Low blood pressure
- Complications from abnormal levels of sodium and potassium, which can affect your heart, kidneys and other parts of your body
ALD testing may be used with other tests to help diagnose adrenal gland disorders. It can also help find out if other medical conditions are affecting the way your adrenal glands work.
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.
Comparing renin and ALD levels helps show whether abnormal levels of ALD are caused by a problem with your adrenal glands or a problem with your kidneys or other parts of the system that triggers the production of ALD.
Other names: aldosterone, serum; aldosterone urine; aldosterone-renin ratio test; aldosterone-plasma renin activity
What is it used for?
An aldosterone (ALD) test is mainly used with a renin test to find out whether too much ALD is the cause of high blood pressure that:
- Happens with low potassium levels
- Doesn't improve with usual blood pressure medicines
- Develops at a young age
An ALD test is also used to help:
Why do I need an aldosterone test?
You may need this test if your health care provider thinks you may have too much or too little aldosterone (ALD).
Signs and 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
- Arrhythmia (a problem with the rate or rhythm of your heartbeat)
- Increased thirst and urination
Signs and symptoms of too little ALD (called hypoaldosteronism) include:
- Low blood pressure
- Test results that show high potassium and/or low sodium levels
- 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 aldosteronism (also called Conn syndrome). This disorder is usually caused by a benign (not cancerous) tumor on an adrenal gland that produces extra ALD.
- Secondary aldosteronism. This means that 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:
In general, lower than normal amounts of ALD may mean you have:
- Addison disease (also called adrenal insufficiency). With this condition, damage to your adrenal glands causes low ALD. The damage may be from conditions, such as:
- Congenital adrenal hyperplasia (CAH). This is a group of genetic disorders you're born with.
- Secondary adrenal insufficiency. This condition starts with a problem in your pituitary, a gland at the base of your brain that controls your adrenal glands.
- Tertiary adrenal insufficiency. With this condition, low ALD levels are 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.
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