The London Endocrine Centre

Adrenal Disease

WHAT ARE THE ADRENAL GLANDS?

The adrenal glands are ductless hormone (endocrine) organs that secrete hormones directly into the bloodstream. They are normally small golden-yellow triangle shaped glands located on top of each kidney. The gland consists of an outer part (cortex) and inner part (medulla).

The adrenal cortex is where steroid hormones are made principally cortisol, , testosterone, oestrogen, DHEA, and aldosterone. Cortisol is one of the body’s most important hormones; its principal role is to help the body respond to stress. Cortisol also contributes to other roles including:

The hormone aldosterone, together with the kidneys, regulates the balance of sodium and potassium in the body and plays a major role in maintaining normal blood pressure.

The adrenal medulla produces adrenaline (epinephrine) and noradrenaline (norepinephrine ), the ‘fight or flight’ hormones, the secretion of which increases in stressful situations.

Disorders of adrenal function can be broadly broken down into three groups:

DIAGNOSIS OF ADRENAL DYSFUNCTION

If there is a suspicion of a disturbance in adrenal function, it is possible to measure the levels of hormones such as cortisol, aldosterone, adrenaline, and ACTH in the blood, plasma, and/or urine. There are also supplementary tests that involve the injection of substances and the measurement of the hormonal response compared to the normal responses. For example an analogue of ACTH may be injected which should increase adrenal hormone output. If this does not happen then the adrenal gland may be failing. Conversely, a very potent steroid (dexamethasone) can be given to assess its ability to suppress the normal cortisol production in a patients suspected of having Cushing's syndrome.

If adrenal disease is suspected, imaging studies (e.g. abdominal x-ray, MRI, CT scan, arteriography, radionuclide scanning etc.) will be used to demonstrate an abnormality that may aid in the diagnosis.

ADDISON'S DISEASE: ADRENAL INSUFFICIENCY

Addison's disease - chronic adrenal insufficiency or hypocortisolism – is a failure of the adrenal gland to secrete sufficient cortisol. It is usually the consequence of adrenal disease and is characterised by:

Skin changes also are common in Addison's disease, with areas of hyperpigmentation or dark tanning that are mostly visible in skin creases, scars, toes, lips, mucous membranes, and skin pressure points such as around both large (e.g elbows, knees) and small (e.g. knuckles) joints.

CUSHING'S SYNDROME

The overproduction of cortisol by the adrenal glands leads to Cushing's syndrome but this can also, and more commonly, be caused by the prolonged and excessive intake of glucocorticoid drugs such as prednisolone, methylprednisolone, or dexamethasone. Glucocorticoids are often present in skin creams used for eczema or psoriasis and will be absorbed through the skin resulting in Cushing’s syndrome. The overproduction of cortisol by the adrenal glands can be caused by a pituitary tumor producing too much ACTH (adrenocorticotropic hormone) or due to a benign or malignant tumor outside the pituitary such as in the lung, thymus gland, or pancreas. The pituitary form of the disease is called Cushing's disease.

Cushing's syndrome is characterized by:

Women with Cushing's syndrome will usually have excess inappropriate hair growth on their face, neck, chest, abdomen and thighs that can be disfiguring. In women the menstrual periods may be irregular. Men may have decreased fertility and a reduced desire for sex.

CONN’S SYNDROME

Conn’s syndrome is a condition characterised by the excess production of aldosterone. This may be produced either by both adrenal glands that are dysfunctional or by a single adrenal benign tumour (adenoma). The hormone aldosterone plays a key role in the maintainance of normal salt balance in the blood. The excess production of aldosterone in Conn’s syndrome causes a high blood pressure typically but not necessarily with a low serum potassium. The disease can be treated medically but if caused by a single adenoma is cured by surgical removal of the affected adrenal gland (adrenalectomy), which today is generally performed via a key hole technique – a laparoscopic adrenalectomy.

PHAEOCHROMOCYTOMA

Pheochromocytomas are tumours of the adrenal medulla. Most phaeochromocytomas produce excess amounts of adrenaline or noradrenaline and as such may cause episodic severe elevations in blood pressure, which can be fatal. The typical symptoms of this disease include:

The diagnosis of a pheochromocytoma relies on having an index of suspicion that initiates the biochemical investigations. These include a 24 hour urine collections to measure levels of adrenaline and noradrenaline, and their breakdown products, metanephrines. Blood levels may also be measured but the episodic nature of the tumour secretion makes this less reliable. Indeed it is frequently necessary to measure the urinary catecholamines on several occasions to make the diagnosis. Once the biochemical diagnosis has been made localization studies are required to identify the site of the hormone overproduction. These include CT, ultrasound and MRI scans and radionucleide imaging.

Once diagnosed the biochemical effects of excess catecholamine secretion must be treated immediately in order to make the patient safe from the potentially fatal blood pressure fluctuations. This should be followed by surgery that usually takes the form of a laparoscopic (key hole) adrenalectomy.

Adrenal Surgery

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