Adrenal Incidentaloma

The adrenal gland sits on top of each kidney and secretes different hormones. Each person has two adrenal glands, one on the left and one on the right.

Download the adrenal incidentaloma information sheet.

An adrenal incidentaloma is a mass (tumour) of the adrenal gland that is found by accident on a scan performed for another reason, for example a CT scan looking for a cause for abdominal pain. As imaging scans have become better, the diagnosis of adrenal incidentalomas has become more common.

Around 1-6% of adults have an adrenal incidentaloma, and the chance of having an adrenal incidentaloma increases with age.1 Almost all adrenal incidentalomas are benign (not cancerous). Less than a third of adrenal incidentalomas produce hormones.2 Usually only one adrenal has an incidentaloma, but sometimes there can be one in each adrenal gland.

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Most people with an adrenal incidentaloma do not have any symptoms. If an adrenal incidentaloma is very large, it may cause abdominal pain or discomfort, but this is uncommon.

If an adrenal incidentaloma secretes hormones, it may cause symptoms, such as those listed below. However, these symptoms are not specific and could be caused by something else. It is important to discuss any symptoms you may have with your doctor.

• High blood pressure with or without low potassium levels in the blood
• Episodes of headache, heart beating fast, and sweating
• High blood sugars (diabetes)
• Bone fractures
• Weight gain despite no change to your lifestyle
• Thinning of your skin and easy bruising
• Muscle weakness

When an adrenal incidentaloma is identified, your doctor will refer you to an endocrinologist, or sometimes, an endocrine surgeon. There are two main things to check:

1) That it is not cancer: you can often tell if a tumour is non-cancerous by its appearance on CT imaging:

a. Size: Adrenal incidentalomas less than 4cm in diameter are less likely to be cancerous.

b. Density: Low density incidentalomas (less than 10 Hounsfield Units) are highly reassuring against cancer. For incidentalomas greater than 10 Hounsfield Unit density on a non-contrast scan, how easily contrast washes out of the incidentaloma can provide important information as to whether it may be cancerous or not

c. Further Imaging (if needed): In a minority of select cases, further specialised imaging may be required, for example PET or MRI, or repeat CT imaging after 3-6 months. In most cases, this is not required.

2) That it is not secreting excess hormones (see ‘What tests are required to assess if the adrenal incidentaloma is secreting excess hormones?’).

What tests are required to assess if the adrenal incidentaloma is secreting excess hormones?

There are three main sets of hormones that need to be checked, because the adrenal incidentaloma may be secreting excess amounts of these hormones. In addition to these blood tests, your doctor will ask you about related symptoms. The sets of hormones to be tested are:

1) Aldosterone and renin

• These hormones regulate blood pressure through salt and water balance in the body.
• They are checked on a blood test. Many medications interfere with the results of this blood test, causing either false negatives or false positives, so your doctor may transition you temporarily to alternative medications that do not interfere with this blood test.
• Excess aldosterone (usually accompanied by a suppressed renin) can lead to high blood pressure and low potassium and warrants further investigation to confirm whether its due to the adrenal incidentaloma.
• For information about primary aldosteronism (excess aldosterone due to the adrenal glands), see the primary aldosteronism factsheet on the Hormones Australia website.

2) Cortisol

• This is the stress hormone of the body, and it controls a range of processes including sugar and fat metabolism.
• It can be checked with a blood test, urine test, saliva test, or combination of these. The urine test involves a 24-hour urine collection. The saliva test involves swabbing the inside of your mouth for a saliva (spit) sample just before bedtime. The blood test involves taking tablets of a medication called dexamethasone at 11pm then getting a blood test done the next morning at 8-9am (known as dexamethasone suppression test).
• The test that is commonly performed when an adrenal incidentaloma is identified is the dexamethasone suppression test, but your doctor will advise which test(s) are the most appropriate for you.

3) Catecholamines (and its breakdown product metanephrines)

• These are the ‘fight and flight’ hormones of the body, for example adrenaline, and among many processes, they regulate blood pressure and heart rate.
• They are checked with a blood test, performed after sitting for 30 minutes, and/or a 24-hour urine collection.
• Excess metanephrines warrant further investigation to confirm whether its due to the adrenal incidentaloma or from another source.

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If the adrenal incidentaloma is not secreting any hormones and has no suspicious features on imaging, no further treatment or follow-up is required. If there are excess hormone production or any suspicious features on imaging, your doctor will discuss further tests and management with you.

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You should see a doctor if you have an adrenal incidentaloma. They may refer you to an endocrinologist for review of the adrenal incidentaloma’s appearance and to check if it is secreting any hormones.

Seeing your doctor or having a medical problem can be stressful. It often takes time for information to sink in, and it is common to feel overwhelmed by what is happening.

Sometimes it helps to write down questions before you go.

Some questions that might be useful for you are:

• How big is my adrenal incidentaloma and is it on the right or left side?
• Is my adrenal incidentaloma secreting hormones?
• Does my adrenal incidentaloma have any concerning features?
• What blood or urine tests are needed?
• Will I need to repeat imaging and if so, when?
• How long do I need to be followed up for?
• Do I need to see an endocrinologist or surgeon?

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Benign – a benign tumour is one that is not cancerous

Malignant – Contains cancerous cells.

Tumour – an abnormal swelling or growth in the body. Can be benign or malignant.

References

1. Kebebew E. Adrenal incidentaloma. N Engl J Med. 2021 Apr 22;384(16):1542-51.

2. Sconfienza E, Tetti M, Forestiero V, Veglio F, Mulatero P, Monticone S. Prevalence of functioning adrenal incidentalomas: a systematic review and meta-analysis. J Clin Endocrinol Metab. 2023 Jul;108(7):1813-23.

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Created by Dr Joanna Gong (Endocrinologist, Royal Melbourne Hospital and Baker Heart and Diabetes Institute)

Reviewed by Dr Angela Xun-Nan Chen (Endocrinologist, Westmead Hospital and The George Institute for Global Health), Professor David Torpy (Endocrinologist, Royal Adelaide Hospital and University of Adelaide), Dr Arunan Sriravindrarajah (Endocrinologist, Royal Prince Alfred Hospital) and the National Adrenal Diseases Foundation (patient advocates).

Last reviewed 10 June 2026