About Adrenals

ADRENAL GLANDS

Anatomy 

There are 2 adrenal glands, left and right, each positioned at the back of the abdomen just above corresponding kidneys. A normal adrenal gland weighs 3-5 grams and measures 5 x 3 x 1 cm. They receive arterial blood supply from several small branches of the inferior phrenic artery, aorta and renal artery. Adrenals are not symmetrical, the right is more triangular and its short and wide adrenal vein drains medially into inferior vena cava, left more semilunar with the vein draining downwards into the left renal vein. Lymphatic capillaries of cortex follow arteries while the medulla lymphatics follow veins

Each adrenal gland is really two distinctive endocrine organs, one surrounding the other. The inner part is adrenal medulla (10%) which secretes catecholamines such as adrenaline and noradrenaline. Adrenal medullary hormones are not essential for life, but they prepare the individual to deal with emergencies (fight or flight) The outer part is called cortex (90%) and it secrets steroid hormones: mineralocorticoids (aldosterone), glucocorticoids (cortisol) and sex hormones, the first 2 are essential for survival. Secretion of cortisol is controlled primarily by ACTH from the part of the brain called anterior pituitary while secretion of aldosterone is a subject to independent control by circulating factor angiotensin II.

Physiology

Catecholamines are secreted from the adrenal medulla in response to nerve stimulus and they increase the rate and strength of heart beats and constrict most blood vessels. Their overall effect is to increase blood pressure.

Steroid hormones are secreted by 3 different zones of the adrenal cortex. Most external zone (glomerulosa) secretes aldosterone under the control of renin-angiotensin system. Aldosterone regulates concentration of sodium and potassium and is responsible for maintaining blood pressure. Too much aldosterone (hyperaldosteronism or Conns syndrome) leads to high blood pressure and low potassium.

Middle zone of adrenal cortex (fasciculata) secretes cortisol under the control of ACTH. Cortisol is responsible for regulating carbohydrates, protein and fat metabolism. Too much cortisol leads to Cushing syndrome if the over secretion is caused by adrenal adenoma, carcinoma or hyperplasia. Cushing disease is diagnosed if too much cortisol is the result of over secretion of ACTH by the pituitary tumour.

The inner zone secretes sex hormones and their excess causes masculinization.

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It is adrenal insufficiency which results from inadequate function of adrenal cortex. Hypoadrenalism might be due to its destruction by autoimmune process (Addison disease), surgical removal of both adrenal glands, malfunctioning pituitary or suppression of normal regulation by taking steroids tablets over a long period of time (i.e. hydrocortisone, dexamethasone, prednisolone). Chronic symptoms include anorexia, weight loss, muscle weakness and low blood pressure. Hypoadrenalism can present as an emergency with shock, severe hypotension and abdominal pain and can be triggered by infection or surgery. Adrenal insufficiency is treated with oral hydrocortisone and mineralocortocoids.

This condition is the result of autonomous excessive production and secretion of adrenal cortex hormone called aldosterone. Aldosterone is a mineralocorticoid and regulates concentration of sodium and potassium. Too much aldosterone leads to low potassium levels in the blood and high blood pressure, which very often is difficult to control even with 2 or 3 antihypertensive medications. Conns’ syndrome is the cause of high blood pressure in about 10% of patient with hypertension. It is usually assumed that 10% of general population is hypertensive, so it is easy to calculate that 1% of people might be affected by this condition.

Excessive secretion of aldosterone could be coming from one of the adrenal glands (usually adenoma) or both of them (usually hyperplasia). Diagnostic work up includes measuring blood pressure, potassium, aldosterone and renin blood levels. CT or MRI is necessary to identify the size and side of the nodule. Often adrenal venous sampling is necessary to establish whether excessive secretion of aldosterone comes from right, left or both adrenal glands. New nuclear scans such as methomidate can also provide this information.

The best treatment for Conns syndrome is laparoscopic adrenalectomy if the source of aldosterone production is only in one of the glands. Successful surgery will normally correct low potassium in nearly a 100% of patients and blood pressure in about 70%. Sometimes hypertension persists but requires fewer medications to control it. If disease affects both adrenals, long term treatment with antihypertensive medications is necessary.

Cushing syndrome results from chronic excess of hormone cortisol. This can happen when small tumour in the pituitary produces too much hormone ACTH, which in turn will stimulate adrenal glands to secrete too much cortisol. Another form of Cushing syndrome happens when adrenal gland itself undergoes pathological change. Commonest adrenal nodules causing over-secretion of cortisol are cortical adenoma (<6cm), carcinoma (>6cm) and hyperplasia (1cm). Adrenal tumours are more common in women with peak incidence in 4th and 5th decade.

Clinical features of Cushing syndrome are progressive and they can be present for several years before the diagnosis is made. Chronic excess of cortisol can cause weight gain with trunk obesity but thin limbs and moon like face, acne, excessive hair, muscle weakness, thin easily bruising skin and mood disturbance. In a long term it can cause high blood pressure, diabetes and osteoporosis.

Diagnostic work up usually includes careful examination, measuring blood pressure and levels of cortisol, ACTH and other hormones. It might be necessary to measure cortisol levels in the urine collected over 24h or perform dynamic test such as dexamethasone suppression test. MRI, CT venous sampling procedures of pituitary gland and adrenal are important to precisely localise source of cortisol over-secretion, size of the tumour and its relation to surrounding anatomical structures.

Cushing disease due to over-secretion of ACTH is treated by removing pituitary tumour through the nose. If this treatment is not successful it might be necessary to remove both adrenal glands, preferably by performing bilateral laparoscopic adrenalectomy. Cushing syndrome caused by adrenal adenoma or hyperplasia can be treated by unilateral laparoscopic adrenalectomy with very good long term results. Sometimes after this operation contralateral gland is not functioning well straight away and it is necessary for the patient to be treated with hydrocortisone for some months. Adrenal carcinoma is usually a big tumour and should be treated by open adrenalectomy and often post operative chemotherapy with mitotane is necessary.

Phaeochromocytomas are tumours which arise from adrenal medulla and secrete too much adrenaline, noradrenaline and dopamine. Paragangliomas are tumours arising from extra adrenal medullary tissue positioned along the aorta. Most of them are sporadic and unilateral but up to 25% of them could be bilateral and caused by a mutated gene, which can be inherited from one of the parents. It is difficult to predict their biological behaviour but 10 – 20% of them are malignant.

Patients present with headaches, sweating, hypertension and palpitations. Biochemical diagnosis is established by measuring catecholamines and metanephrines levels in urine and plasma. CT, MRI and MIBG (metaiodobenzylguanidine) scans are used to assess tumour location, size and detect possible metastases. Often genetic test is necessary to assess whether mutated gene is causing the disease. It is important to know this as inherited mutations are often associated with other endocrine abnormalities which will have to be investigated before surgery. If the genetic test is positive, other members of the family should undergo genetic screening.

All patients with phaeochromocytomas must be carefully prepared with medications to block a and sometimes b receptors to minimize the risk of hypertensive crisis during surgery. Excessive manipulation of the tumour can sudden rise of blood pressure leading to stroke or heart attack. It is important to work with an experienced anaesthetist who is able to control surges of blood pressure during dissection and hypotension after the removal of the tumour. Most of the adrenalectomies for phaeochromocytoma could be performed laparoscopically, only very large tumours require open adrenalectomy.

Diagnosis of adrenal diseases usually require blood or urine tests to assess the function of the gland. Very often some routine blood test such as full blood count, renal and liver function tests and inflammatory markers to evaluate general health are necessary. Special endocrine tests measure levels of hormones either in the urine or in the blood. Adrenal hormones secreted by cortex are cortisol, aldosterone and androgens. Medulla secretes adrenaline, noradrenaline and dopamine. Sometimes ACTH and renin, which are secreted by pituitary gland in the brain are measured. There might be a need to perform dynamic tests such as overnight dexamethasone suppression test (Cushing) or short Synacthen test (adrenal insufficiency). Adrenal vein sampling, performed by collecting venous samples directly from the veins draining the gland and measuring levels of hormones in them, is usually used in patients with Conns syndrome

Imaging scans are performed to assess the size and exact position of the adrenal mass as well as its relation to surrounding anatomical structures. Adrenal imaging is best performed by CT or MRI scans but often nuclear scans such MIBG or octreotride scintigraphy.

Adrenal incidentaloma is an incidentally detected adrenal lesion during the scans performed for reasons other than imaging adrenal gland. This incidental detection is becoming more common because of increased number of imaging procedures such as CT, MRI, ultrasound and PET scans. The incidence of adrenal incidentaloma is around 3 to 4%.

Firstly, once the diagnosis of adrenal mass is made, it is important to determine whether incidentally discovered adrenal mass is functioning and associated with excessive production and secretion of hormones and secondly, whether it’s malignant or benign.

Excessive production of adrenal hormones could be ascertained clinically by noting possible signs or symptoms such as high blood pressure, obesity, weakness or excessive hair. More often blood and urine tests are necessary to confirm this diagnosis. These tests include measuring the blood levels of cortisol, ACTH, catecholamines, potassium, aldosterone and renin. Sometimes it is necessary to perform dynamic tests such as overnight dexamethasone suppression test or short synacthen test. Over-secretion of cortisol or aldosterone causes respectively Cushing or Conns syndrome. Phaeochromocytoma is diagnosed if tumour secretes abnormal quantities of adrenaline and noradrenaline. Adrenal nodules which are functioning should be removed surgically, ideally by performing laparoscopic adrenalectomy.

Distinguishing between benign and malignant mass is more difficult. Typical radiological appearances often will strongly suggest either benign or malignant pathology. Previous history of cancer in other organs might raise a question of metastasis to the adrenal gland, even if it is a long time since the cancer was treated. Adrenocortical carcinoma arises from adrenal cortex itself and should be treated by resection. Examples of benign tumours are adrenal cyst, lipoma, adenoma, myelolipoma or hematoma. If doubts persist as to the nature of the adrenal mass, those which are bigger than 4 cm should be removed surgically. If they are smaller than 4 cm, CT or MRI scans should be repeated at 3, 6 and 12 months looking for increase in size. If previous scans are available, this information could be obtained by comparing current and old scans. Nodules which are increasing over time should be also removed because they could be cancers.

Commonest indications for adrenal surgery are:

  • Primary hyperaldosteronism also known as Conns syndrome (too much aldosterone)
  • Cushing syndrome (too much cortisol)
  • Phaeochromocytoma (too much adrenaline also could be malignant)
  • Adrenal cancer (risk of metastases and over-secretion of adrenal cortex hormones)
  • Metastases to adrenal from cancers in other parts of the body

Adrenocortical carcinoma is a rare but highly malignant tumour with poor prognosis. 60% of adrenal cancers are hormonally active and can cause Cushing or virilizing syndromes. Most of these tumours are large at diagnosis and an open approach should be used to resect them. Surgery often needs to be extensive with en block removal of adrenal and surrounding organs combined with removal of the lymph nodes. Tumour spillage must be avoided at all cost to prevent local recurrence. It is often necessary to have chemotherapy with drug called mitotane which can cause adrenal insufficiency and treatment with glucocorticoids might be necessary. Monitoring mitotane levels might be helpful and other forms of chemotherapy might be used.

Adrenalectomy is a surgical procedure during which one or rarely both adrenal glands are removed. It is not a common operation and should ideally be done only in centers performing at least 10 -15 cases per year. Adrenalectomy is not an operation for ‘an occasional adrenalectomist’. Looking after patients requiring adrenal surgery is a team exercise all cases must be discuss with the endocrinologist, radiologist and anaesthetist.

In the last 20 years a major change of paradigm for adrenal surgery took place in that open adrenalectomy has been largely replaced by laparoscopic approach. Adrenalectomy is ideally suited to laparoscopic surgery and a great majority of these procedures are performed using transperitoneal or retroperitoneal minimally invasive technique. Laparoscopic approach significantly reduces trauma of open incision and results in less pain, quicker recovery and better cosmetic results. It is performed through 3 or 4 small abdominal incisions 1 – 2cm long, which are used for long instruments to manipulate gland and a camera.

Open adrenelectomy is nowadays reserved for either very large or malignant tumours. These open operations are performed through larger abdominal incisions which are either longitudinal in a midline or horizontal across abdomen.

Commonest operation on the adrenal is removal of one of the glands and it is frequently performed for Conns and Cushing syndromes, phaeochromocytomas and other indications. Most of these operations are performed laparoscopically.

Sometimes removal of the part of the adrenal gland affected by the disease can be attempted. This is frequently considered when disease is bilateral or hereditary and the benefit of this approach is the preservation of some the adrenal function.

Bilateral adrenalectomy is an operation when both adrenal glands are removed. This is indicated in patients with Cushing disease if pituitary surgery failed to control excessive production of ACTH. It is also performed for bilateral phaeochromocytomas when no adrenal tissue can be spared.

Adrenal surgery is performed under general anaesthetic.  No food or drink is allowed for 6 hours before the procedure.  Sometimes patients need a special preoperative treatment with medications to make an operation safer.

The laparoscopic adrenalectomy is performed through 3 or 4 small incision used for long instruments and camera. Open adrenalectomy is performed through larger abdominal incisions. The incisions vary in length depending on the size of the adrenal mass and the size and shape of your abdomen. 

Sometimes it is necessary to spend first postoperative night on the Intensive Care Unit to monitor your blood pressure and other parameters but most patients will return to their rooms after surgery

After the operation you will be moved to recovery room and then return to your ward where regular blood pressure, pulse and oxygen levels will be checked.  There will also be a drip in your arm through which fluids and other medications will be given as necessary. Sometimes it is necessary to spend first postoperative night on the Intensive Care Unit to monitor your blood pressure and other parameters.

You might experience some pain, discomfort and stiffness around the incisions after the operation. In the majority of patients’ pain can be adequately controlled with tablets but sometimes injections are necessary.  After surgery you will be encouraged to perform gentle leg exercises to prevent formation of blood clots and deep breathing to improve ventilation of your lungs.

Immediately after the operation you might feel sore and uncomfortable and have some discomfort when swallowing.  These changes are temporary and self limiting and you will be able to swallow, eat and drink few hours after the operation. 

The average stay in hospital after laparoscopic adrenalectomy is 1night.  Patients who had open surgery stay in the hospital for 3 or 4 days but sometimes longer hospitalisation is necessary to allow full recovery. However, you will probably need another 7-14 days off work to recover from it.

After a bilateral adrenalectomy lifelong replacement of glucocorticoids and mineralocorticoids is always necessary. Medications need to be taken 3 times a day and the dose might have to be adjusted if you are unwell with infection or another surgery is planned. You will be given emergency supply of hydrocortisone injections in case of any unforeseen events and you should be wearing a bracelet indicating that your own adrenals do not work properly.

After removal of only one adrenal gland most of patients do not require medications but occasionally the contralateral gland does not function straight away and medications are necessary for few months.

Most adrenal operations are straightforward and associated with few problems, however all operations carry the risk and complications specific for adrenal surgery include:

  • Wound infection
  • Post-operative bleeding
  • Damage to organs surrounding adrenal such as liver, kidney, pancreas, spleen, large or small bowel. If the damage is detected during the laparoscopic surgery and can not be repaired using this minimally invasive approach, a conversion to open surgery is necessary. This happens in about 1% of operations
  • Unsightly scar
  • Miscellaneous problems due to anaesthesia, but these are very rare.

The position of the scars will be explained to you by the surgeon.  In laparoscopic surgery small 1-2 cm incisions are used, left adrenalectomy requires 3 and right 4 incisions. Open adrenalectomy is performed through larger abdominal incisions. The incisions vary in length depending on the size of the adrenal mass and the size and shape of your abdomen.  They are either longitudinal in a midline or horizontal across abdomen.

Scars after adrenalectomy usually heals very well and most of the time are not very noticeable. The scar may become relatively thick and red for a few months after the operation before fading to a think white line.  Very rarely some patients develop a thick, exaggerated scar but this is uncommon.

The most important way to look after your wound is to keep it clean and dry.  During the first week the scar might be a little bit swollen and tender to touch but this should settle.  To make the scar look and heal better you can rub a small amount of cream, such as E45 or vitamin E cream which can soften the scar and improve healing.

Wound infections after adrenal surgery are very infrequent and affect about 1% of patients. Wound infection usually occurs 3-4 days after surgery and presents with red and tender swelling around scar, fever and general unwellness. It is very important to contact your surgeon as soon as you realise that infection might be developing. Urgent treatment with antibiotics is usually needed but in very rare situation an operation to evacuate infected fluid is necessary. Patients with Cushing syndrome are at the increased risk of infection because their immunological responses are compromised by too much cortisol.

Adrenal is a very vascular gland and many arteries and veins supplying it have to be sealed during surgery. Post-operative bleeding is nowadays very rare and affect fewer than 1% of patients. If this happens patient needs to be taken back to theatre to evacuate the clot and stop bleeding. This is why we recommend you should stay in the hospital overnight as this complication is extremely rare after 24 hours. Patients taking medications interfering with blood clotting (aspirin, warfarin) must stop them before surgery.

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