Testing for Adrenal Gland Function

Tests for High and Low Cortisol and Aldosterone

Adrenal Gland, CT scan
Adrenal Gland, CT scan. Getty Images/BSIP/UIG

You think that there may be something wrong with your adrenal. Have you been feeling tired? Are you feeling dizzy and lightheaded? You may need to have your adrenal gland tested. Understanding the different types of tests that your doctor can order is important in finding the most reliable test for you. 

There are three different ways that adrenal function can be evaluated: blood, urine and saliva testing.

The key is to understand how each test is used with regards to a specific adrenal gland problem. 

The adrenal glands may produce too much or too little cortisol, and they are guided by a cycle of cues. When your cortisol levels drop, the hypothalamus area of your brain releases corticotropin-releasing hormone (CRH). That tells the pituitary gland, also located in the brain, to release adrenocorticotropic hormone (ACTH), which is what stimulates the adrenal glands on top of the kidneys to produce and release cortisol. When something goes wrong in this sequence, you can end up with too much or too little cortisol being produced.

The secretion of each of the hormones isn't constant, it changes throughout the day and night, making testing dependent on timing, Your doctor will often look at the levels of hormones three ways -- in the blood, urine and saliva to be able to diagnose an adrenal condition.

It takes more than a single test for your doctor to be able to diagnose the source of a problem with your adrenal function.

Tests When Too Much Cortisol Is Suspected

Cushing syndrome is a condition of having an abnormally high cortisol production. A blood test can show whether cortisol is elevated, but it measures both protein-bound inactive cortisol as well as free active cortisol.

It is more of a snapshot view, as your levels vary within the day.

If it is high, your doctor will then measure 24-hour urinary cortisol, which is a better indicator of how your glands are functioning rather than the snapshot view of the blood test. Your doctor may also do a salivary cortisol test, which shows only the free cortisol. It is done near bedtime, at the time your levels should be lowest.

An overnight dexamethasone suppression test may also be done. In this test, you would have your blood drawn, then get a dose of a synthetic glucocorticoid. This should result in your cortisol levels dropping. You then have your blood drawn at intervals to see if cortisol levels drop as they should in normal function.

In Cushing syndrome, the pattern would be normal or high cortisol when waking up and no drop by bedtime. Your doctor would then analyze the pattern further and do additional tests to see where the problem lies - in the adrenal glands, pituitary gland or a tumor.

Tests When Low Cortisol Production Is Suspected

Addison disease and adrenal insufficiency are two conditions where cortisol is low.

If your blood cortisol level test results show it is low, your doctor may order an ACTH stimulation test. In this test, you receive an injection of synthetic ACTH. This should cause your cortisol levels to rise if everything is functioning normally. You will have blood drawn at intervals to check the cortisol levels.

If your cortisol levels don't respond to ACTH, it points toward a problem with the adrenal glands, which may be primary adrenal insufficiency or Addison disease. If your cortisol levels rise with ACTH, this points to a problem with the pituitary gland and secondary adrenal insufficiency.

Tests When High Aldosterone Is Suspected

Aldosterone is a hormone that regulates the salt balance in your blood, which influences your blood pressure and blood volume. In Conn syndrome, or primary hyperaldosteronism, the symptoms are high blood pressure and retaining sodium and potassium. If it is suspected, your doctor would order aldosterone and renin blood tests.

It is in the interpretation of how these two hormones interact together that your doctor can determine if you have this condition. Normally, when your blood pressure in the kidneys is low, renin is released, and it increases aldosterone. When renin drops, aldosterone drops. Benign adrenal tumors or overactive adrenals for unknown reasons can cause high aldosterone without high renin.

Secondary aldosteronism can be caused by anything that increases renin levels. This may be low blood flow to the kidneys and other reasons. In this condition, both renin and aldosterone would be high.

Salivary Testing in Alternative Health

Many alternative health care practitioners will advocate for salivary testing. They may think salivary testing of cortisol and other hormones represents the dynamic physiology and hormones in our body. Many doctors will not consider salivary testing by itself for their patients, although endocrinologists use salivary testing when evaluating for Cushing syndrome. Alternative health practitioners use salivary testing for examining adrenal fatigue, especially the salivary cortisol test.


Conn Syndrome, LabTestsOnline, American Association for Clinical Chemistry, February 26, 2013.

Cortisol, LabTestsOnline, American Association for Clinical Chemistry, October 30, 2015.

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