A Tour around the Adrenal Gland

(Date of publication 15 August 2005)

In today's fervently age-conscious society, where maturity is widely regarded as a social handicap on a par with halitosis, why should women hoping to maintain their youthful good looks spend their days at sea level? And what could this possibly have to do with the adrenal gland? The answer is that women who live at high altitudes appear to age more quickly, because of lower levels of the adrenal hormones DHEA and DHEAS (dehydroepiandrosterone and dehydroepiandrosterone sulphate). However, a healthy adrenal gland does much more than act as endogenous botox...

This diagram shows the adrenal glands positioned at the upper pole of each kidney. Each one is buried in fat, as can be seen in this photograph, and is composed of an outer cortex and inner medulla. The cortex uses cholesterol to manufacture three types of steroid hormones: glucocorticoids, mineralocorticoids and androgens. Glucocorticoids have a potent anti-inflammatory effect on the body and depress the immune response, the most abundant example being hydrocortisone or cortisol, while the important mineralocorticoid aldosterone promotes the re-absorption of sodium ions by the kidney, to help maintain normal blood pressure. Microscopic examination reveals that the cortex has three concentric zones with different cellular arrangements. The medulla consists of neurons which form part of the sympathetic nervous system and release adrenaline and noradrenaline into the bloodstream, in preparation for 'fight or flight'.

Prolonged exposure to elevated levels of glucocorticoids, most commonly from taking steroids, can lead to Cushing Syndrome. The cause may also be endogenous – overproduction of glucocorticoids as a result of neoplasia. Sufferers develop multiple medical problems, including hypertension, obesity, osteoporosis, fractures, impaired immune function and wound healing, glucose intolerance, and psychosis. Some characteristic features of the condition are illustrated in these photographs: truncal obesity, 'moon' face and purple striae on the abdomen. Taking steroids can suppress the hypothalamo-pituitary-adrenal (HPA) axis for up to a year after their use has been discontinued to relieve symptoms. During this period the patient needs stress doses of steroids during an illness to prevent an adrenal crisis. If neoplasia is responsible, treatment may involve surgery, radiation or drug therapy.

Adrenal insufficiency, or Addison's Disease, occurs when the cortex does not produce enough cortisol and, in some cases, aldosterone. In addition to weight loss, muscular weakness, fatigue and low blood pressure, this condition often produces a distinctive darkening of the skin in both exposed and unexposed areas of the body, as here. Most cases of primary adrenal insufficiency, which originates in the gland itself, are the result of autoimmune disorders in which the cortex is attacked by the patient's own antibodies – signs and symptoms develop when more than 90% has been destroyed. Much more common, however, is insufficiency secondary to a lack of adrenocorticotrophic hormone (ACTH) from the pituitary gland. As insufficiency progresses slowly and insidiously, it is often ignored until an illness or accident causes a sudden deterioration – this is an addisonian crisis, which can be fatal. Treatment of Addison's Disease is by oral replacement therapy, but a crisis may require intravenous hydrocortisone, saline and dextrose.

In patients with Conn's Syndrome, or primary hyperaldosteronism, the retention of salt and loss of potassium by the kidney results in hypertension, which is usually unresponsive to standard medical therapy. The cause is over-production of aldosterone, most frequently by an adenoma – a cortical tumour that is typically benign – but sometimes by hyperplasia or malignancy. Surgical removal of the affected gland significantly improves or completely cures the hypertension in 80% to 90% of patients. If you are interested in the various operative procedures that may be employed, and the factors which influence the surgeon's choice of technique, the EndocrineWeb.com site has a great deal of relevant information.

Benign and malignant tumours of the adrenal cortex are briefly outlined here (ignore the title!), where the point is made that cortical cancers may become very large. The example in this photograph is many times the size of the original gland. The treatment of adrenocortical carcinoma depends upon the particular stage, from a single tumour of less than 5 centimetres (Stage I) to one that has spread into local tissues and lymph nodes, or has metastasised (Stage IV).

An important tumour of the medulla is the pheochromocytoma, usually benign, because it secretes adrenaline and noradrenaline. The increase in blood pressure that results can be very extreme. Typically, sudden hypertensive episodes lasting less than an hour are triggered by physical, emotional or pharmacological stimuli, including bending over, fear and tobacco. Foods rich in tyramine (e.g. beer, wine and cheese), from which adrenaline and noradrenaline are synthesised, are a particular culprit. Other symptoms can include a rapid pulse, palpitations, profuse sweating, headache and nausea. The success rate of surgical excision in relieving symptoms appears to depend upon whether the hypertension was sporadic (up to 95%) or long-lasting (75%).

Finally, this endocrine organ seems to be inextricably involved in Chronic Fatigue Syndrome. Sufferers have low levels of hydrocortisone and one small-scale study found their adrenal glands to be decreased in size by 50%. However, trials of replacement therapy have had mixed results, and one reported that adrenal gland suppression followed treatment – more research is definitely needed.

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