What are adrenal glands?
The adrenal glands are paired, mustard-coloured structures that are positioned superior and slightly medial to the kidneys in the retroperitoneal space. They are flattened and roughly pyramidal or crescent shaped and weigh approximately 4 gr each. The adrenal gland contains an outer (cortex) and an inner (medulla) zone. The adrenal glands are the factories of hormones and produce a number of hormones that are vital for the normal function of our body.
Most people-and depending on the underlying pathology- can live a completely normal life without any need for hormone supplementation even if one adrenal gland has to be removed (adrenalectomy).
Role of the adrenal glands
Each adrenal gland is composed of two distinct parts: the outer part called the adrenal cortex and the inner adrenal medulla. The adrenal glands secrete different hormones which act as ‘chemical messengers’. These hormones travel in the bloodstream and act on various body tissues to enable them to function correctly. All adrenocortical hormones are steroid compounds made from cholesterol.
The adrenal cortex produces three hormones:
- Mineralocorticoids: the most important of which is aldosterone. This hormone helps to maintain the body’s salt and water levels which, in turn, regulates blood pressure. Without aldosterone, the kidney loses excessive amounts of salt (sodium) and, consequently, water, leading to severe dehydration and low blood pressure.
- Glucocorticoids: predominantly cortisol. This hormone is involved in the response to illness and also helps to regulate body metabolism. Cortisol stimulates glucose production helping the body to free up the necessary ingredients from storage (fat and muscle) to make glucose. Cortisol also has significant anti-inflammatory effects.
- Adrenal androgens: male sex hormones mainly dehydroepiandrosterone (DHEA) and testosterone. All have weak effects, but play a role in Precocious puberty and early development of the male sex organs in childhood, and female body hair during puberty.
The adrenal medulla produces catecholamines:
Catecholamines include adrenaline, noradrenaline and small amounts of dopamine – these hormones are responsible for all the physiological characteristics of the stress response, the so called ‘fight or flight’ response.
Commonly, overproduction of aldosterone can occur, which causes a condition known as primary hyperaldosteronism. This causes high blood pressure, which is resistant to conventional blood pressure control tablets, and salt disturbances. High blood pressure may cause headaches and visual problems. Some studies have suggested that hyperaldosteronism may account for up to 5% of all people with high blood pressure and an even higher proportion of those who have treatment-resistant hypertension.
A keyhole operation to remove the adrenal gland that produces the excess aldosterone hormone is safe, with minimal morbidity and can have very beneficial effects on the health of the patients. A selected group of patients might even be completely cured from their hypertension after the adrenalectomy.
A keyhole operation to remove the adrenal gland that produces the excess cortisol is safe, with minimal morbidity and can have very beneficial effects on the health of the patients. Some patients might require life-long cortisol supplementation in the form of a tablet.
Tumours of the adrenal glands (adrenocortical cancer and metastasis to the adrenal gland)
Adrenocortical cancer is very rare and can present without any particular symptoms (picked up incidentally on a scan) or because of overproduction of hormones such as cortisol and androgens. The mainstay of the treatment of ACC’s is to remove the adrenal gland together with any involved organ in the proximity. Patients with ACC require life-long follow-up, genetic screening and might require further surgical or medical treatments (mitotane) as the cancer might come back in the same spot or metastasise to other places in the body.
A number of cancers from organs distant to the adrenals (kidney, lung, breast, bowel) can metastasise to the adrenal gland(s). In some cases and depending on the exact findings, it is possible to remove the affected adrenal gland that harbours the metastatic cells with a key-hole operation/adrenalectomy.
The treatment of each disorder varies according to the specific cause. Patients with any concerns about these conditions should seek advice from their doctor.
Tumours of the adrenal gland are mostly benign and do not result in over or underproduction of adrenal hormones. Most tumours are discovered incidentally when people undergo scans for various other reasons. Once detected, most adrenal nodules will require a specialist set of investigations and follow-up scans to ascertain the benign nature of the nodule.