adrenal incidentaloma
The Facts You Need To Know – Download Fact Sheet
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What is Adrenal Incidentaloma?
Since the early 1980’s, there has been widespread use of imaging of the chest and abdomen with CT and MRI for a variety of disorders. A very common finding is an unsuspected adrenal mass with a diameter of more than 1 cm, now referred to as an adrenal incidentaloma. The incidence increases with age, from 0.2% in childhood to 7% in old age. Once discovered, the evaluation of the mass centers on two concerns:
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Reveals an enlarged-right-adrenal mass.
https://www.researchgate.net/figure/Reveals-an-enlarged-right-adrenal-mass-s-o-Pheochromocytoma_fig2_377025363 |
Imaging
New techniques using CT and MRI have been very useful in separating benign from malignant adrenal tumors.
Hormonal evaluation
The adrenal glands make several hormones. The most important are cortisol and aldosterone from the adrenal cortex and epinephrine from the adrenal medulla.
Most adrenal incidentalomas do not produce an excess of any of these hormones and therefore do not cause any symptoms or signs of disease. Those that do produce excess hormone may lead to one of the following conditions:
Testing for hormone excess:
Management
If the adrenal mass is greater than 4 cm, especially if it has grown from a previous image, surgery is appropriate because there is a high risk of adrenal cortical carcinoma, a very aggressive cancer. For masses less than 4 cm, the management will depend on the results of the hormonal evaluation.
If all hormone testing is normal, follow up with another imaging in one year is typical, but if the mass is close to the threshold of 4 cm, a 6-month repeat is appropriate. However, since most small non-functioning adrenal adenomas do not grow significantly, it is currently acceptable to re-image and test again only if there is a clinical change.
If the cortisol testing suggests Cushing’s syndrome, further testing is required. Ultimately, if the diagnosis of Cushing’s from an adrenal adenoma is confirmed, surgery is indicated.
When the tests suggest MACS with no overt signs of Cushing’s, initial non-surgical management is appropriate, with regular repeat testing for blood and urine cortisol secretion. Since even slight persistent excess production of cortisol may have significant effects, there should be careful monitoring for hypertension, type 2 diabetes, elevated lipids, weight gain, osteoporosis, psychiatric changes, thin skin, and muscle wasting. Medical treatment for weight, diabetes, hypertension and osteoporosis may be adequate, but if these physical signs worsen and cortisol secretion increases, surgery may be considered.
Primary aldosteronism requires further testing prior to considering surgery as a potential cure. Pheochromocytoma is treated with surgery after medical management to minimize complications from excision of the tumor.
Why Consult an Endocrinologist?
Endocrinologists have the knowledge and experience to select the proper evaluation and interpretation of the results, which often require additional studies. They play an important role in referrals to appropriate surgical specialists and management of pre-op and post-operative hormonal effects of the tumor. Where non-surgical medical treatment is appropriate, endocrinologists are best equipped to guide treatment of MACS and to schedule follow up imaging when required. Experienced endocrinologists will provide advice to primary doctors and surgeons, avoiding unnecessary imaging and hormonal testing in the majority of cases of small non-functioning adrenal incidentalomas.
Written by Paul Margulies, MD, FACE, FACP, Medical Director, NADF
New techniques using CT and MRI have been very useful in separating benign from malignant adrenal tumors.
- Benign features: Fatty tumors and cysts are almost always benign.
- Tumor size: Very large tumors, especially 6 cm or greater, are at high risk of being malignant.
- Growth Rate: Rapid growth is a warning sign for malignancy.
- PET scans: This is usually done in follow up of a known malignancy. Intense uptake in the adrenal can be seen in adrenal cancer, but can also be caused by metastases to the adrenal from another malignancy.
Hormonal evaluation
The adrenal glands make several hormones. The most important are cortisol and aldosterone from the adrenal cortex and epinephrine from the adrenal medulla.
Most adrenal incidentalomas do not produce an excess of any of these hormones and therefore do not cause any symptoms or signs of disease. Those that do produce excess hormone may lead to one of the following conditions:
- An excess of cortisol would cause Cushing’s syndrome, but it might be subtle.
- An excess of aldosterone is called primary aldosteronism and will cause high blood pressure.
- An excess of epinephrine from an adrenal is called pheochromocytoma and will cause high blood pressure.
Testing for hormone excess:
- Cortisol: All adrenal incidentalomas should be tested for autonomous cortisol secretion with a basic 1 mg overnight dexamethasone suppression test measuring serum cortisol in the morning.
- If there is a failure to suppress, especially if there are signs of Cushing’s syndrome, further testing is necessary.
- If there is a partial suppression in the absence of overt Cushing’s it is called mild autonomous cortisol secretion or MACS. The prevalence of MACS in adrenal incidentalomas was thought to be 5 to 30%, but a recent study from the UK found 48% of benign adrenal adenomas had an abnormal dexamethasone suppression test.
- Additionally, low morning plasma ACTH and DHEAS levels are helpful to confirm autonomous function.
- Aldosterone: If hypertension or hypokalemia (low potassium) is present, blood testing for plasma aldosterone and plasma renin is necessary to rule out primary aldosteronism. The aldosterone-renin ratio is normally below 20 to 40. The prevalence in incidentalomas is 1.1 to 10%.
- Screening for pheochromocytoma tests for an excess of epinephrine by measuring the metabolites of epinephrine in blood or urine. This is called plasma or urinary fractionated metanephrines. Classic pheochromocytoma features are high blood pressure, palpitations, sweating and headaches, but these symptoms may be absent.
Management
If the adrenal mass is greater than 4 cm, especially if it has grown from a previous image, surgery is appropriate because there is a high risk of adrenal cortical carcinoma, a very aggressive cancer. For masses less than 4 cm, the management will depend on the results of the hormonal evaluation.
If all hormone testing is normal, follow up with another imaging in one year is typical, but if the mass is close to the threshold of 4 cm, a 6-month repeat is appropriate. However, since most small non-functioning adrenal adenomas do not grow significantly, it is currently acceptable to re-image and test again only if there is a clinical change.
If the cortisol testing suggests Cushing’s syndrome, further testing is required. Ultimately, if the diagnosis of Cushing’s from an adrenal adenoma is confirmed, surgery is indicated.
When the tests suggest MACS with no overt signs of Cushing’s, initial non-surgical management is appropriate, with regular repeat testing for blood and urine cortisol secretion. Since even slight persistent excess production of cortisol may have significant effects, there should be careful monitoring for hypertension, type 2 diabetes, elevated lipids, weight gain, osteoporosis, psychiatric changes, thin skin, and muscle wasting. Medical treatment for weight, diabetes, hypertension and osteoporosis may be adequate, but if these physical signs worsen and cortisol secretion increases, surgery may be considered.
Primary aldosteronism requires further testing prior to considering surgery as a potential cure. Pheochromocytoma is treated with surgery after medical management to minimize complications from excision of the tumor.
Why Consult an Endocrinologist?
Endocrinologists have the knowledge and experience to select the proper evaluation and interpretation of the results, which often require additional studies. They play an important role in referrals to appropriate surgical specialists and management of pre-op and post-operative hormonal effects of the tumor. Where non-surgical medical treatment is appropriate, endocrinologists are best equipped to guide treatment of MACS and to schedule follow up imaging when required. Experienced endocrinologists will provide advice to primary doctors and surgeons, avoiding unnecessary imaging and hormonal testing in the majority of cases of small non-functioning adrenal incidentalomas.
Written by Paul Margulies, MD, FACE, FACP, Medical Director, NADF
