Aldosterone Test (Hypoaldosteronism)

WeightQ&AMeongsiljang Veterinary Advisory Board

An aldosterone test is a blood test that measures the concentration of this adrenal hormone to diagnose hypoaldosteronism. I’ll walk you through the testing procedure, how to interpret the results, and what preparation is needed.

What Is an Aldosterone Test?

A dog undergoing an aldosterone test with its veterinarian

The aldosterone test measures the concentration of aldosterone, a hormone secreted by the adrenal glands, in the blood to diagnose hypoaldosteronism. What’s truly important is that this test is rarely interpreted in isolation; it’s typically evaluated alongside an ACTH stimulation test. Your veterinarian may recommend this test if your pet is experiencing recurring lethargy, vomiting, weight loss, and abnormal electrolyte levels (sodium and potassium).

Why Measure Aldosterone?

Aldosterone is secreted by the adrenal cortex and helps the body retain sodium while excreting potassium. When there is a deficiency of this hormone, a condition called hypoaldosteronism (a form of Addison's disease) develops, leading to elevated potassium levels and decreased sodium levels in the blood. As a result, the heart rate slows down, and the risk of dehydration and shock increases. Therefore, directly measuring these levels is crucial for diagnosis.

Comparison of Key Aldosterone-Related Tests

Item	Baseline aldosterone	ACTH stimulation test	Electrolyte panel
Measurement target	Blood aldosterone concentration	Cortisol and aldosterone before and after stimulation	Sodium, potassium, chloride
Number of blood draws	Once	Twice (before and after injection)	Once
Time required	About 10 minutes	About 1–2 hours	About 10 minutes
Main use	Supportive diagnosis	Confirmatory test	Screening

The actual test combination is decided by the veterinarian based on symptoms and the results of the initial blood test.

How the Test Is Performed

The test begins with drawing a small amount of blood from the front leg or jugular vein. If an ACTH stimulation test is also performed, a second blood sample is taken one hour after administering synthetic ACTH. Since the samples are sent to an external specialized laboratory, results typically take 2–5 days. Bringing a familiar blanket or treats can help keep your pet calm and reduce stress on the day of the test.

A cat being drawn for blood to test adrenal hormones.

Go to the Vet Immediately If You See These Symptoms

If your pet has experienced repeated vomiting and diarrhea, severe lethargy, loss of appetite, and weight loss for more than two weeks, along with occasional collapsing or trembling, it could be an Addisonian crisis. This is an emergency situation that can lead to cardiac arrest. If your pet hasn’t eaten for over 24 hours or appears extremely weak and limp, please take them to a 24-hour veterinary clinic immediately.

Pre-Test Preparation and Medications to Watch

- Fasting: Typically, an 8- to 12-hour fast is required (water is allowed freely). - Medication discontinuation: Medications such as steroids and diuretics can affect test results, so be sure to inform your veterinarian of any medications your pet is currently taking. - Condition check: Avoid strenuous exercise and bathing the day before the exam. - Cat-specific considerations: Cats may experience fluctuating test values due to stress, so maintaining a quiet environment is essential.

Pre-aldosterone test preparation checklist for your pet

How to Interpret the Results

- Normal range: Reference values vary slightly by laboratory, but for dogs, baseline levels typically range from 14 to 957 pmol/L, and post-stimulation levels from 197 to 2103 pmol/L. - Low levels: This raises suspicion of hypoaldosteronism (Addison’s disease), often prompting confirmatory testing. - High levels: This may suggest primary hyperaldosteronism (reported in both dogs and cats, but more common in cats) or a tumor. Results must always be interpreted by a veterinarian in conjunction with clinical signs and electrolyte levels.

Management After Diagnosis

Once hypoaldosteronism is confirmed, lifelong supplementation with mineralocorticoids (via injection or oral medication) and glucocorticoids is required. Your veterinarian will determine the dosage and administration schedule based on your pet’s weight, symptoms, and electrolyte levels. Regular electrolyte monitoring is essential, and temporary dosage adjustments may be needed during stressful situations such as surgery, travel, or moving. With proper management, this condition allows for a normal life expectancy.

Breed and Age Considerations

In dogs, the risk is known to be slightly higher in Standard Poodles, Portuguese Water Dogs, Nova Scotia Duck Tolling Retrievers, Bearded Collies, Great Danes, West Highland White Terriers, Rottweilers, and Springer Spaniels. The condition typically appears in dogs from young age through middle age, and tends to be reported more frequently in females than in males. However, because the exact age of onset and sex ratio vary considerably among individuals and studies, it is difficult to draw definitive conclusions, so please treat this information as a general reference. In cats, primary hyperaldosteronism (Conn’s syndrome) is more common than hypoaldosteronism, with hypertension and hypokalemia serving as key indicators, typically in senior cats around 12 years of age.

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently Asked Questions

How much does the test cost?

Costs vary significantly depending on the clinic and the specific combination of tests, so it’s difficult to give a single, definitive price. Since many veterinarians recommend pairing the basic aldosterone test with an ACTH stimulation test and an electrolyte panel, I suggest contacting your clinic in advance to get a detailed cost estimate.

Is this test included in the health checkup?

This specialized test isn’t included in a routine health checkup. It’s performed as an additional, tailored examination when symptoms are suspected or when abnormal sodium or potassium levels are detected in a basic blood test.

Can a single test confirm the diagnosis?

A basic aldosterone test alone is not enough to confirm a diagnosis; it must be interpreted alongside ACTH stimulation tests and cortisol measurements. If borderline results are obtained, we may recommend retesting after a certain period.

Will my pet be uncomfortable after the examination?

The amount of blood drawn is small, so most pets recover right away. However, since the ACTH stimulation test requires staying at the clinic for 1–2 hours, it’s a good idea to discuss with your veterinarian beforehand whether sedation might be helpful for anxious pets.

Can hypoaldosteronism be cured?

This condition is managed through lifelong hormone supplementation rather than being cured. With consistent medication and monitoring, your pet can enjoy a normal daily life and lifespan without significant issues.

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References

[1] Feldman EC, Nelson RW, Reusch CE, Scott-Moncrieff JCR. Canine and Feline Endocrinology, 4th Edition, Chapter 12: Hypoadrenocorticism

[2] Ettinger SJ, Feldman EC, Cote E. Textbook of Veterinary Internal Medicine, 8th Edition

[3] Plumb DC. Veterinary Drug Handbook (수의약리학 교과서)