Health Centres - Adrenal adenomas
What is an adrenal adenoma?
The adrenal glands are situated over the top of each kidney.
Adrenal adenomas are benign (non-cancerous) tumours of the adrenal gland. They arise from the outer layer of the gland, called the adrenal cortex.
The adrenal cortex normally makes hormones that belong to the steroid family.
If an adrenal adenoma produces hormones, it is called 'functioning', though this term makes them sound healthy when in fact such adenomas often produce excessive amounts of steroid hormones.
If an adenoma does not produce a hormone it is termed 'non-functioning'.
Adrenal adenomas are often found by chance during a scan of the body for an unrelated condition. However, all adrenal masses (lumps) need careful evaluation to ascertain their nature, especially to see whether they are producing hormones.
If an adrenal adenoma that is producing hormones is not treated, it can have serious consequences (see figure and case illustration below).
Case illustration
In this MRI scan the image cuts through the abdomen at the level of the adrenal glands, just above the kidneys. It is presented as if looking up from the patient's feet, so the spine is in the lower middle of the picture and right and left are transposed.
The arrow shows a lump in the right adrenal gland. This was a chance discovery when the patient had scans because of jaundice due to a small cancer of the opening of the bile duct from the liver .
The liver (L) and spleen (S) are shown. Examination of the patient by the author revealed clinical signs of Cushing's syndrome, which was subsequently confirmed by biochemical tests.
The adenoma was producing cortisol and this was blocked for six weeks, with the drug metyrapone, to allow the tissues to recover from Cushing's syndrome and to improve wound healing.
The patient then had an operation to remove both the right adrenal gland and the cancer. Because of the overproduction of cortisol from the tumour, the patient's otherwise healthy left adrenal gland had reduced its cortisol production to a level that would have been too low to supply the body's cortisol needs immediately after the tumour removal. This would have been a dangerous situation called hypoadrenalism and it was avoided by giving the patient synthetic cortisol (hydrocortisone) until the gland began to function normally again. This took six months in this patient, who has subsequently done well.
What causes adrenal adenomas?
Adrenal adenomas are more common in some inherited diseases, including multiple endocrine neoplasia type I, Beckwith-Wiedemann syndrome and the Carney complex.
Also, patients with genetic defects of the body systems that manufacture steroid hormones (eg congenital adrenal hyperplasia), especially those whose condition is poorly controlled, may have a higher risk of adrenal adenomas. However, most adrenal adenomas are not linked with an inherited disease.
The likelihood of developing an adenoma increases with age. Benign adrenal adenomas are found in 1 to 32 per cent of people at autopsy, with most studies showing a detection rate of about 5 per cent.
About 6 per cent of patients over 60 years of age harbour an adrenal adenoma. No other predisposing factors have been defined, and prevention is not possible.
What are the symptoms?
Most patients with an adrenal adenoma will have no symptoms caused by the adenoma. However, even in symptom-free patients, proper investigations reveal that many adrenal adenomas produce abnormal amounts of steroid hormones to some degree.
The commonest abnormality is the production of too much cortisol, a steroid hormone involved in the response to stress and energy balance.
Adenomas that produce massive amounts of steroid hormones will cause obvious symptoms. Large amounts of cortisol will cause Cushing's syndrome, too much aldosterone causes Conn's syndrome, and an excess of male sex steroids causes acne and hair growth.
Very rarely, bleeding can occur into adenomas and cause pain in the flanks or back.
How are adrenal adenomas diagnosed?
Most adrenal adenomas are discovered by chance when an abdominal computed-tomography or magnetic-resonance imaging scan is done for unrelated symptoms.
Studies have found that CT scanning identifies a so-called incidental adrenal lump in about 0.3 to 11 per cent of people. As many as 80 per cent of people with such masses will have a benign non-functioning adenoma.
What else could it be?
More rarely, a mass in the adrenal gland is cancer that has spread from another part of the body, usually the lung or bowel (ie 'metastatic' cancer).
Generally, the origin of the cancer is clear from the clinical examination or from simple tests such as a chest X-ray.
In addition, the CT or MRI appearance of metastatic cancer in the adrenal gland can be distinguished from a benign adrenal adenoma by use of specialised radiology.
An adrenal mass might also be a cancer of the adrenal cortex (adrenocortical carcinoma). Although they are very rare, these cancers are often large and can produce a combination of hormones.
Adrenal masses can also arise from the inner part of the adrenal gland, called the adrenal medulla, which is part of the nervous system and produces the 'fight-or-flight' hormones adrenaline and noradrenaline.
Tumours of the adrenal medulla are called phaeochromocytomas, and they also can be distinguished from adenomas by specialised scanning techniques as well as by blood and urine tests for adrenaline and noradrenaline.
What can your doctor do?
Adrenal masses require specialised scans and hormone investigations, and most patients should be referred to an endocrinologist. The endocrinologist will look for signs of Cushing's syndrome, Conn's syndrome, hair growth, acne, and will check the blood pressure.
A general examination will be performed to search for cancerous growths elsewhere.
The endocrinologist will also carry out specialised tests to check different hormone levels. Patients on the oral contraceptive pill will be advised to stop taking it six weeks before any blood tests are done because the female sex hormones in the pill make interpretation of the blood levels of steroid hormones very difficult. They would be advised to use barrier methods (eg condoms with spermicidal creams) instead.
Tests will usually include:
- a 24-hour urine collection for adrenaline and noradrenaline.
- blood tests for:
potassium (a type of salt, the balance of which in the body is controlled by the adrenal gland hormones)
- renin and aldosterone activity (both are hormones involved in blood pressure control. Renin is influenced by posture, so is measured when lying down)
- male sex hormones (testosterone, 17-hydroxyprogesterone, dihydroepiandrostenedione, and androstenedione)
- female sex hormones (oestradiol and progesterone).
- a 'low-dose dexamethasone suppression test'. This test checks the body's control of cortisol secretion. It involves taking the drug dexamethasone (a synthetic steroid) by mouth then having blood taken for cortisol levels. Normally the body would reduce its own production of cortisol as a response to the extra steroid of the dexamethasone dose. An adrenal adenoma however keeps on producing cortisol despite the dexamethasone.
Additional scans may be needed, including a chest X-ray and an MRI scan of the adrenal glands.
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