What Is an Aldosterone Test?
An aldosterone (ALD) test measures the amount of ALD in your blood. It’s also called a serum aldosterone test. ALD is a hormone made by the adrenal glands. The adrenal glands are found on top of your kidneys and are responsible for producing several important hormones. ALD affects blood pressure and also regulates sodium (salt) and potassium in your blood, among other functions.
Too much ALD can contribute to high blood pressure and low potassium levels. It’s known as hyperaldosteronism when your body makes too much ALD. Primary hyperaldosteronism could be caused by an adrenal tumor (usually benign, or noncancerous). Meanwhile, secondary hyperaldosteronism could be caused by a variety of conditions. These include:
- congestive heart failure
- some kidney diseases (e.g., nephrotic syndrome)
- excess potassium
- low sodium
- toxemia from pregnancy
What Does an Aldosterone Test Diagnose?
An ALD test is often used to diagnose fluid and electrolyte disorders. These may be caused by:
- heart problems
- kidney failure
- diabetes insipidus
- adrenal disease
The test can also help diagnose:
- high blood pressure that is hard to control or occurs at a young age
- orthostatic hypotension (low blood pressure caused by standing up)
- overproduction of ALD
- adrenal insufficiency (under active adrenal glands)
Preparing for Aldosterone Testing
Your doctor may ask you to have this test at a certain time of day. The timing is important, as ALD levels vary throughout the day. Levels are highest in the morning. Your doctor may also ask you to:
- change the amount of sodium you eat (called sodium restriction diet)
- avoid strenuous exercise
- avoid eating licorice (licorice can mimic aldosterone properties)
- These factors can affect ALD levels. Stress may also temporarily increase ALD.
A number of medications can affect ALD. Tell your doctor about all medications you are taking. This includes supplements and over-the-counter drugs. Your doctor will tell you if you need to stop or change any medications before this test.
Medications that can affect ALD include:
- nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen
- diuretics (water pills)
- oral contraceptives (birth control pills)
- angiotensin-converting enzyme (ACE) inhibitors, such as benazepril
- steroids, such as prednisone
- beta blockers, such as bisoprolol
- calcium channel blockers, such as amlodipine
How Aldosterone Testing Is Done
ALD testing requires a blood sample. The blood sample can be taken in your doctor’s office or it can be performed in a lab.
First, an area on your arm or hand will be disinfected. An elastic band will be wrapped around your upper arm to make blood collect in the vein. A small needle will be inserted into your vein and this may be slightly to moderately painful. It may cause a stinging or pricking sensation. Blood will be collected in one or more tubes.
The elastic bland and the needle will then be removed and pressure will be applied to the puncture to stop bleeding. This also helps prevent bruising. A bandage will be applied. The puncture site may continue to throb, but this goes away within a few minutes for most people.
The risks of having your blood drawn are low. It’s considered a non-invasive medical test. Possible risks of having your blood drawn include:
- multiple needle pricks due to trouble finding a vein
- excessive bleeding
- lightheadedness or fainting
- hematoma (blood pooling under the skin)
- infection at the puncture site
Interpreting Your Results
Your doctor will review the information collected by the test. They’ll reach out to you at a later date to discuss your results.
High levels of ALD are called hyperaldosteronism. This can increase blood sodium and lower blood potassium. Hyperaldosteronism can be caused by:
- renal artery stenosis (narrowing of the artery that supplies blood to the kidney)
- congestive heart failure
- kidney disease or failure
- cirrhosis (scarring of the liver)toxemia of pregnancy
- a diet extremely low in sodium
- Conn syndrome, Cushing’s syndrome, or Bartter syndrome (rarely)
Low ALD levels are called hypoaldosteronism. Symptoms of this condition include:
- low blood pressure
- low sodium levels
- low potassium levels
Hypoaldosteronism can be caused by:
- adrenal insufficiency
- Addison’s disease, which affects adrenal hormone production
- hyporeninemic hypoaldosteronism (low ALD caused by kidney disease)
- a diet very high in sodium (more than 2,300 mg/ day for those age 50 and under; 1,500 over age 50)
- congenital adrenal hyperplasia (a congenital disorder in which infants lack the enzyme needed to make cortisol, which can also affect ALD production.)
After the Test
Once your doctor has reviewed your results with you, they may order other tests to help diagnose the over-production or under-production of ALD. These tests include:
- plasma renin
- renin-ALD ratio
- andrenocorticotrophin (ACTH) infusion
- intravenous (IV) saline infusion
These tests will help you and your doctor learn more about what’s causing the issue with your ALD. This will help your doctor find a diagnosis and come up with a treatment plan.