Adrenal mass found by chance: follow-up tests
The adrenal glands are two small organs that sit on top of each kidney and make hormones such as cortisol, aldosterone and adrenaline. (MedlinePlus) An adrenal incidentaloma is a lump of 1 cm or more in an adrenal gland, found on a scan done for an unrelated reason. Modern CT and MRI scans find one in about 4 to 5% of adults and 7 to 10% of older adults. (ESE/ENSAT 2023, open-access review) This page covers the follow-up scans and hormone tests guidance lists, not surgery, biopsy or treatment.
The main guidance
The European Society of Endocrinology (ESE) and the European Network for the Study of Adrenal Tumors (ENSAT) updated their adrenal incidentaloma guideline in 2023; it is cited here through an open-access review published in 2025. (ESE/ENSAT 2023, open-access review) In the US, the American Association of Clinical Endocrinologists and American Association of Endocrine Surgeons (AACE/AAES) published guidance in 2009, and the American College of Radiology (ACR) updated its white paper on incidental adrenal findings in 2017; both are cited through a second open-access review from 2025. (Seow 2025 review)
Who it applies to
The definition leaves out masses found through planned screening of people with a genetic syndrome that raises the risk of adrenal tumors, and masses found while staging or checking a known cancer elsewhere in the body. (ESE/ENSAT 2023, open-access review) The review says children, young adults and pregnant people with an adrenal mass need prompt assessment, with MRI preferred over CT to avoid radiation. (ESE/ENSAT 2023, open-access review)
The scan: CT density and size
The first step is a CT scan without contrast. The density of the mass is measured in Hounsfield units (HU). A smooth, even mass of 10 HU or less is a fat-rich adenoma, which is benign, and needs no more imaging. (ESE/ENSAT 2023, open-access review) Masses above 10 HU need more checks, which can include a CT with contrast, MRI or PET-CT. (ESE/ENSAT 2023, open-access review) Size matters too: the review puts the risk of adrenal cancer at about 2% under 4 cm, 6% from 4.1 to 6 cm and 25% over 6 cm. (ESE/ENSAT 2023, open-access review)
The hormone tests
About 15% of adrenal masses found by chance make extra hormones, so the guidelines ask for hormone testing as well as the scan. (Seow 2025 review)
| Test | Who | What it looks for |
|---|---|---|
| Overnight 1 mg dexamethasone suppression test | Everyone with an adrenal incidentaloma (ESE/ENSAT 2023) | Too much cortisol. A morning cortisol of 50 nmol/L (1.8 µg/dL) or less after the test generally rules it out; above 138 nmol/L (5 µg/dL) shows clear cortisol excess; results in between are called possible autonomous cortisol secretion. |
| Aldosterone and renin (aldosterone-to-renin ratio) | People with high blood pressure or unexplained low potassium | Primary aldosteronism (too much aldosterone) |
| Plasma free or 24-hour urine metanephrines | Masses that are not clearly benign on CT; ESE 2023 dropped this test for masses under 10 HU | Pheochromocytoma (a tumor that makes adrenaline-like hormones) |
| Sex hormones and steroid precursors | Only when signs or the scan suggest it | Hormone changes linked to adrenal cancer |
Sources for the table: the ESE/ENSAT 2023 guideline as summarized in the Mirica review (ESE/ENSAT 2023, open-access review) and the change to metanephrine testing described in the Seow review. (Seow 2025 review) The review says people with mild autonomous cortisol secretion should be checked for high blood pressure, diabetes, high cholesterol, obesity and osteoporosis. (ESE/ENSAT 2023, open-access review) For blood pressure checks, see screenings if you have high blood pressure.
Repeat checks and when
- Clearly benign mass (10 HU or less, even): no repeat imaging. (ESE/ENSAT 2023, open-access review)
- Not clearly benign and being watched: a repeat scan at 6 to 12 months. Growth of more than 20% in size and at least 5 mm across counts as significant growth; below that, the guidance lists another scan after 6 to 12 months. (ESE/ENSAT 2023, open-access review)
- Hormone tests: not repeated routinely if the first tests were fully normal, unless new symptoms appear or related health problems get worse. (ESE/ENSAT 2023, open-access review)
- Autonomous cortisol secretion: the review describes yearly clinical follow-up for up to 5 years for people with related health problems. (ESE/ENSAT 2023, open-access review)
Routine age-based screening
An adrenal mass found by chance does not replace the routine screenings for your age. For other findings on a scan, see lung nodule found by chance: follow-up scans; for the rest, see screenings by age and gender.
Where they differ:
- Repeat scans for a benign-looking mass. AACE/AAES 2009 advised a repeat scan at 3 to 6 months, then yearly for 1 to 2 years, for masses under 4 cm and under 10 HU; the ACR 2017 white paper advised no follow-up imaging for masses of 10 HU or less, fat-containing myelolipomas, or masses stable for 1 year or more. (Seow 2025 review) ESE/ENSAT 2023 advises no repeat imaging for an even mass of 10 HU or less. (ESE/ENSAT 2023, open-access review)
- The CT cut-off. The guidelines use 10 HU. The 2025 Seow review proposes raising it to 20 HU for masses under 4 cm and dropping washout CT; this is a proposal, not a guideline. (Seow 2025 review)
- Metanephrine testing. Before its 2023 revision, the ESE guideline included this test for every adrenal mass; the 2023 version dropped it for masses under 10 HU. (Seow 2025 review)
Your doctor decides what your result means for you.
Questions people ask
Is an adrenal mass found by chance usually serious?
Usually not. The 2025 review of the ESE/ENSAT guideline says most are harmless adenomas that make no extra hormones, and puts the chance of adrenal cancer at about 2% for masses under 4 cm. (ESE/ENSAT 2023, open-access review)
Will I need more scans?
Not always. Under the ESE/ENSAT 2023 guideline, a smooth, even mass of 10 Hounsfield units (HU) or less on a CT without contrast needs no more imaging. Masses that are not clearly benign get a repeat scan at 6 to 12 months if they are being watched. (ESE/ENSAT 2023, open-access review)
Why are hormone tests advised?
About 15% of adrenal masses found by chance make extra hormones, and these can be missed on a scan. The guidelines recommend first-time hormone testing for these masses. (Seow 2025 review)
Which hormone tests are listed?
An overnight 1 mg dexamethasone suppression test for cortisol in everyone; aldosterone and renin in people with high blood pressure or low potassium; and metanephrines for masses that are not clearly benign on CT. (ESE/ENSAT 2023, open-access review) (Seow 2025 review)
Do the hormone tests need repeating every year?
Under the ESE/ENSAT 2023 guideline, no. If the first tests are normal, repeat hormone testing is not advised unless new symptoms appear or related health problems get worse. (ESE/ENSAT 2023, open-access review)
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- Kidney cyst found by chance: Bosniak follow-up
- Lung nodule found by chance: follow-up scans
- Screenings if you have high blood pressure
- Blood pressure readings: what they mean
- Checks if you have primary hyperparathyroidism
- After an abnormal screening result
- False positives and overdiagnosis
- Screenings by age and gender