Aldosterone Test
An aldosterone test measures the levels of the hormone aldosterone in your blood or urine to help diagnose adrenal gland disorders and investigate the causes of abnormal blood pressure.
What is an aldosterone (ALD) test?
An aldosterone (ALD) test measures the amount of aldosterone in your blood or urine. ALD is a hormone produced by your adrenal glands, which are two small glands located above your kidneys. This hormone helps keep your blood pressure stable by balancing the levels of two electrolytes: sodium and potassium.
When blood pressure drops, ALD signals the kidneys to release more sodium into the bloodstream and excrete potassium through urine. This process retains water in the bloodstream, causing blood pressure to rise. Once blood pressure returns to normal, ALD levels decrease.
Abnormal ALD levels can lead to serious health conditions, including:
- High blood pressure
- Low blood pressure
- Complications from electrolyte imbalances affecting the heart, kidneys, and other body systems
ALD testing is often combined with a renin test—a hormone produced by the kidneys—to form an aldosterone-renin ratio test. Comparing these levels helps determine if abnormal ALD is caused by the adrenal glands or by other parts of the body's regulatory system.
What is it used for?
The test is primarily used to determine if excess ALD is causing high blood pressure that is resistant to standard medication, occurs at a young age, or is accompanied by low potassium levels. It is also used to:
- Diagnose adrenal gland disorders
- Identify the cause of abnormal sodium or potassium levels
- Investigate orthostatic hypotension (dizziness upon standing)
Why do I need an aldosterone test?
Your provider may order this test if they suspect your ALD levels are too high (hyperaldosteronism) or too low (hypoaldosteronism).
Symptoms of high ALD (Hyperaldosteronism)
- High blood pressure
- Low potassium or high sodium levels
- Muscle weakness, cramps, or spasms
- Fatigue and headache
- Arrhythmia (irregular heartbeat)
- Increased thirst and urination
Symptoms of low ALD (Hypoaldosteronism)
- Low blood pressure
- High potassium or low sodium levels
- Fatigue and muscle weakness
- Loss of appetite and weight loss
- Abdominal pain
What happens during an aldosterone test?
The test uses either a blood sample or a 24-hour urine collection.
Blood Test
A professional will draw blood from a vein in your arm. Because ALD levels fluctuate based on posture, you may be asked to lie down or stand for a period before the sample is taken.
Urine Test
You will collect all urine over a 24-hour period in a provided container. You must store the container in a refrigerator or cooler with ice throughout the process and return it to the lab as instructed.
Preparation and Risks
Follow your provider's instructions regarding medications, as some may need to be paused. You may also be asked to limit salt intake for two weeks prior. Do not eat natural black licorice for at least two weeks before the test, as it can interfere with results. There is minimal risk to blood tests, typically limited to slight bruising or pain at the needle site; there are no risks associated with urine collection.
What do the results mean?
Results must be interpreted by your provider alongside other clinical data.
- Higher than normal ALD: May indicate primary aldosteronism (Conn syndrome), often caused by a benign tumor, or secondary aldosteronism caused by conditions like kidney disease, heart failure, cirrhosis, or dehydration.
- Lower than normal ALD: May indicate Addison disease (adrenal insufficiency), congenital adrenal hyperplasia (CAH), secondary or tertiary adrenal insufficiency, or Liddle syndrome. Low levels may also be linked to diabetes, lead poisoning, or the use of certain medications like NSAIDs.