Endocrine disordersDr. Dina Hassan Al-Saidi

Diabetes Mellitus• Diabetes mellitus (DM) is a disorder caused by an absolute or relative

lack of insulin: there can be a low output of insulin from the pancreas, or the peripheral tissues may resist insulin. In diabetes, with insulin lacking or its action blocked, glucose cannot enter cells and, without energy, weakness results. Glucose also then accumulates in the blood (hyperglycaemia) and spills over into the urine (glucosuria), taking with it, osmotically, a large amount of water (polyuria).

• This leads to dehydration and thus thirst and the need to drink excessively (polydipsia). As glucose is then no longer a viable energy source, fat and protein stores are metabolized with weight loss, peripheral muscle wasting and, in type 1 diabetes, the production of ketone bodies (acetoacetate, β-hydroxybutyrate and acetone.

• In severe cases, ketone bodies may be detected on the breath (in particular acetone) and accumulate in the blood (ketonaemia) as well as be excreted in the urine (ketonuria). The resultant metabolic ketoacidosis leads to a compensatory increase in respiratory rate (hyperventilation) and a secondary respiratory alkalosis.

• Chronic hyperglycaemia causes microvascular complications, and atherosclerosis, and is a leading cause of death and disability. Diabetes affects about 3–4% of the general population but may be recognized in only 75% of those individuals, yet it is a leading cause of death and disability.

• Risk factors for diabetes include family history; being overweight; inactivity; age (the risk of developing type 2 diabetes rises with age, especially after age 45) and race.

• Diabetes may be primary, or secondary to some other factors as shown in the Table. Type 2 is by far the most common type of diabetes.

Primary Type 1 – insulin-dependent (IDDM); juvenile onset Type 2 – non-insulin-dependent (NIDDM); maturity onset

Secondary Drugs (corticosteroids, thiazide diuretics, beta-blockers) Endocrine disorders (phaeochromocytoma, acromegaly, Cushing syndrome) Pancreatic disease (pancreatitis), haemochromatosis Pregnancy (gestational diabetes) usually represents type 2 diabetes exposed by the increased insulin resistance of pregnancy

Type 1 diabetes• formerly termed insulin-dependent (IDDM) or juvenile-

onset diabetes – is most commonly diagnosed at about 12 years of age and commonly presents before the third decade, but can appear at any age.

• it is characterized by antibodies directed against insulin and the pancreatic islets of Langerhans. It may have a viral (possibly Coxsackie or rubella) aetiology.

• Latent autoimmune diabetes in adults (LADA) is essentially a slow presentation of type 1 diabetes, which is seen in slimmer patients who progress quickly to insulin requirement. Anti-GAD (glutamic acid decarboxylase) antibodies may be helpful in the diagnosis.

Type 2 diabetes• formerly termed non-insulin-dependent (NIDDM) or

maturity-onset diabetes – accounts for 80–90% of diabetics. Generally it occurs in genetically predisposed individuals over the age of 40 who are typically overweight.

• Patients are insulin resistant and have diminished beta-cell function.

• Maturity-onset diabetes of the young (MODY) is caused by autosomal dominant mutations and so there is vertical transmission of diabetes within families. The phenotype varies from mild glucose intolerance to insulin-requiring diabetes, typically diagnosed before the age of 25 years.

Gestational diabetes• It is basically an insulin-resistant state

exposing future risk of type 2 diabetes.• Appears usually in second or third trimester

of pregnancy• Affects up to 5% of pregnant women.

Clinical features• Patients with diabetes may be asymptomatic and detected on

routine or opportunistic screening, or present in a variety of ways related to severity and degree of onset.

• Lethargy is the most common symptom but hyperglycaemia, polyuria and thirst (polydipsia) are prominent.

• Since glucose is lost as an energy source in type 1 diabetes, fats must be metabolized, leading to weight loss from fat breakdown to fatty acids and ketone bodies, which appear in the blood causing acidosis and hyperventilation, and in the urine (ketonuria) and to some extent in the breath (acetone).

• Diabetes is also associated with immune deficiencies, particularly polymorph dysfunction, leading to susceptibility to infections (mainly skin infections and mucosal candidosis).

• Type 1 diabetes develops most often in children and young adults. Symptoms usually develop over a short period. Excessive thirst and urination, constant hunger, weight loss, blurred vision and extreme fatigue are typical.

• Life-threatening diabetic coma (diabetic ketoacidosis) is a significant risk. Insulin is required daily for treatment, for life, and diet must be controlled. Hypoglycaemia is a risk.

• Type 2 diabetes develops most often in overweight patients. Symptoms usually develop gradually.

• Fatigue, frequent urination, unusual thirst, weight loss, blurred vision, frequent infections, and slow healing of wounds or sores are seen.

• Most patients with type 2 diabetes can be managed on diet and oral hypoglycaemic drugs. Many will eventually need insulin, but are often resistant.

• About 80% of people with type 2 diabetes have the metabolic syndrome that includes obesity, elevated blood pressure and high levels of blood lipids.

Acute complications of diabetes• Diabetes can lead to coma. Hypoglycaemic coma is the

main acute complication of diabetes, is growing in frequency with the trend towards tighter metabolic control of diabetes.

• Many insulin-treated patients are liable to hypoglycaemia, due to an imbalance between food intake and usage, and insulin therapy. Hypoglycaemia can be of rapid onset, and may resemble fainting.

• There is adrenaline release, leading to a strong and bounding pulse, sweaty skin, and often anxiety, irritability and disorientation, before consciousness is lost. Occasionally the patient may convulse.

• hypoglycaemia must be quickly corrected with glucose or brain damage can result.

• Glucose will cause little harm in hyperglycaemic coma but will improve hypoglycaemia.

• Never give insulin since this can cause severe brain damage or kill a hypoglycaemic patient. Assess the glucose level with a testing strip.

• If the patient is conscious, give glucose solution or gel (GlucoGel) immediately by mouth or 10 g sugar.

• if the patient is comatose, give 10–20 ml of 20–50% sterile dextrose intravenously or, if a vein cannot readily be found, glucagon 1 mg intramuscularly.

• On arousal, the patient should also be given glucose orally, usually in the form of longer-acting carbohydrate (e.g. bread, biscuits).

• Hyperglycaemic coma usually has a slow onset over many hours, with deepening drowsiness (but unconsciousness is rare, so an unconscious diabetic should always be assumed to be hypoglycaemic).

• signs of dehydration (dry skin, weak pulse, hypotension), acidosis (deep breathing) and ketosis (acetone smell on breath and vomiting) only in type 1 diabetes.

• If it is certain that collapse is due to hyperglycaemic ketoacidotic coma, the first priority is to establish an intravenous infusion line. This enables rapid rehydration to correct dehydration and electrolyte (especially potassium) losses, and the administration of insulin.

• Blood should be taken for baseline measurements of glucose, electrolytes, pH and blood gases. Raised plasma ketone body levels can be demonstrated with a testing strip such as Ketostix (Ames). Insulin is then started, such as 20 units i.m. stat.

• Medical help should be obtained as soon as possible.

Chronic complications of diabetes• Diabetes is associated with long-term

microvascular and macrovascular complications .• Diabetes is a leading cause of death and

disability due to premature cardiovascular disease: the risk of myocardial infarction is at least tripled.

• Renal and retinal complications are also incapacitating, as is gangrene of toes.

• Smoking increases the risk of many chronic complications.

General management• Glycosuria is usually indicative of diabetes,

but absence of glycosuria does not completely exclude it, and confirmation by blood glucose levels is essential.

• Diagnosis is from the presence of raised blood (venous plasma) glucose level

Test Confirms Diabetes Excludes Diabetes

Fasting plasma glucose (after a person has fasted for 8 h)

> 7.0 mmol/L < 6 mmol/L

Random blood glucose (taken any time of day)

≥ 11.1 mmol/L < 8 mmol/Lb

Plasma glucose taken 2 h after a person has consumed a drink containing 75 g of glucose in oral glucose tolerance test (OGTT)

> 11.1 mmol/L < 11.1 mmol/L

• A diagnosis of diabetes is made when any one of the above three tests is positive, with a second test positive on a different day (not needed if symptomatic).

• Pre-diabetes is the term given when there is either of the following:

1. An impaired glucose tolerance (IGT) test – blood glucose during the oral glucose tolerance test is higher than normal but not high enough for a diagnosis of diabetes (7.8–11.0 mmol/L).

2. An impaired fasting glucose (IFG; impaired fasting glycaemia) – fasting plasma glucose is higher than normal (6.1–6.9 mmol/L) but less than the level confirming the presence of diabetes.

• Patients with IGT and IFG are more likely to develop type 2 diabetes, and have an increased risk of cardiovascular disease.

Diabetes prevention1. Weight reduction and greater physical

activity.2. Diet may help diabetic control;

recommendations are to eat more starches such as bread, cereal and starchy vegetables. eat five portions of fruits and vegetables every day.

3. eat fewer sugars and sweets.

• Long-term assessment of glucose control is made by estimation of the blood level of glycosylated haemoglobin (HbA1c).

• HbA1c is normal adult haemoglobin that binds glucose, remains in the circulation for the life of the erythrocyte and therefore acts as a cumulative index of diabetic control over the preceding 3 months; the higher the glycosylated haemoglobin level, the greater the risk of chronic complications.

• Patients should have an HbA1c test every 3–6 months; glycosylated haemoglobin below 4.8% of total haemoglobin is normal. Fructosamine is an alternative assay of long-term diabetic control.

• Optimum control would be to aim to keep blood glucose levels at 4–7 mmol/L before meals (preprandial) and at no higher than 10 mmol/L 2 h after meals (postprandial) and HbA1c (long-term glucose level) optimally at 7% or less.

TreatmentType 1 diabetes• Basic treatment of type 1 diabetes is

subcutaneous insulin administration, the amount being balanced against food intake and daily activities, and home blood glucose testing.

• Insulin may be of human or animal (pork or beef) origin, and comes in various forms: short-acting, intermediate-acting or long-acting insulins; insulin analogues have been modified so as to produce very rapid-onset and very long duration of activity.

• Insulin is given by injection. There is no single standard for patterns of insulin administration. The dose varies widely between patients and also depends on the type of preparation, diet and exercise. Infections or traumas also raise insulin requirements.

The following three insulin regimes are in common use.• 1. Twice-daily doses of short- and intermediate-acting

insulin, often pre-mixed, given before breakfast and before the evening meal. The short-acting doses cover the insulin needs of the morning and evening. The intermediate-acting doses cover the afternoon and overnight.

• 2. Three times a day dosing; short-acting and intermediateacting insulin before breakfast, short-acting insulin before the evening meal and intermediate-acting insulin before bed.

• 3. Multiple daily doses: short-acting insulin used before each main meal and an intermediate- or long-acting insulin used before bedtime to give coverage overnight.

Type 2 diabetes • Basic treatment of type 2 diabetes is by controlled eating

and physical activity, and home blood glucose testing.• In some patients, hypoglycaemic drugs may also be

needed, which may be used as monotherapy or in certain combinations such as dual therapy (e.g. metformin plus a sulfonylurea or sitagliptin; or a glitazone plus sitagliptin).

• Intensive control of blood glucose and blood pressure lowers the risk of blindness, renal disease, stroke and myocardial infarction.

• Gastric bypass surgery provides long-term control for obesity and diabetes in adult-onset diabetes, and also alleviates some of the complications.

Dental Aspects

• There are no specific oral manifestations of diabetes mellitus but, even if well controlled, patients are predisposed to infections, and diabetics have more severe periodontal disease than controls

• If diabetic control is poor, oral candidosis can develop and cause, for example, angular stomatitis.

• Severe dentoalveolar abscesses with fascial space involvement in seemingly healthy individuals may indicate diabetes. Any such patients should be investigated to exclude it and other immune defects.

• In patients with insulin-treated diabetes, circumoral paraesthesia is a common and important sign of impending hypoglycaemia.

• Neuropathy may occasionally cause cranial nerve deficits and occasionally there is swelling of the salivary glands (sialosis) due to autonomic neuropathy.

• A burning mouth sensation in the absence of physical changes may be possible. A dry mouth may result from dehydration.

• The main hazard is hypoglycaemia, as dental disease and treatment may disrupt the normal pattern of food intake.

• Prevent this by planning, such as by administering oral glucose just before the appointment if a patient has taken his or her medication but has not had the appropriate meal.

• Furthermore, particularly before surgical procedures, the patient’s blood glucose level may be tested using a point of care device prior to treatment, and oral glucose given if the level is too low – less than about 5 mmol/L (180 mg/dl).

• If normal eating will not be resumed at lunchtime, a post-operative blood glucose level may be taken and further glucose given.

• In a well-controlled diabetic patient, providing that normal diet has, and can, be taken, it is feasible to carry out even minor surgical procedures, such as simple single extractions under LA, as long as the procedure is carried out within 2 h of breakfast and the morning insulin injection.

• More protracted procedures, such as multiple extractions, must only be carried out in hospital.

• Poorly controlled diabetics (whether type 1 or 2) should also be referred for improved control of their blood glucose before non-emergency treatment is performed.

• Drugs should be sugar-free, avoiding those that can disturb diabetic control: steroids, which increase blood glucose; and doxycycline, tetracyclines and ciprofloxacin, which enhance insulin hypoglycaemia.

• Acetaminophen/paracetamol or codeine are the analgesics of choice.

• Non- steroidal anti-inflammatory drugs (NSAIDs) should be used with caution in view of renal damage and risk of gastrointestinal bleeding, especially as many diabetics are already on low-dose aspirin for prophylaxis of ischaemic heart disease.

• The dentist should manage infections aggressively, as people with diabetes may be immunocompromised

• Amoxicillin is the antibiotic of choice.

• Local analgesia can usually be safely used in diabetics; the dose of adrenaline is unlikely to increase blood glucose levels significantly.

• Conscious sedation with benzodiazepines can usually be safely used.

• Autonomic neuropathy in diabetes can cause orthostatic hypotension; therefore the supine patient should be slowly raised upright in the dental chair.

• Routine non-surgical procedures or short minor surgical procedures under LA can be carried out with no special precautions apart from ensuring that treatment does not interfere with eating.

More protracted procedures, such as multiple extractions, must only be carried out in hospital, with the following precautions

• Pre-operative assessment : before the operation, the patient should be put on soluble insulin and stabilized. Insulin may need to be given twice or three times daily, and control is confirmed by estimation of blood glucose

• The operation should be carried out early in the morning and booked first in the list, so that any delays in the operation schedule will not impair diabetic control

• At 8.00–9.00 am blood should be taken for glucose estimation and an intravenous infusion set up giving glucose 10 g, soluble insulin 2 units and potassium 2 mmol/h (GIK infusion), until normal oral feeding is resumed – at which time the patient can be returned to the pre-operative insulin regimen

• Blood glucose should be monitored at 2–4-hour intervals until the patient is feeding normally

• The patient is put on an insulin sliding scale from the morning of the day of operation until the normal feeding regimen is possible.

• General anaesthesia for the diabetic patient may be complicated especially by hypoglycaemia, chronic renal failure, ischaemic heart disease or autonomic neuropathy. Severe autonomic neuropathy can lead to postural hypotension and impaired ability to respond to hypoglycaemia, and carries a risk of cardiorespiratory arrest under GA.

Adrenal Cortex• The adrenal cortex produces a series of corticosteroids,

mainly cortisol (hydrocortisone) and corticosterone (the glucocorticoids), and aldosterone (the mineralocorticoid).

• Corticosteroids are an essential part of the body’s response to stresses such as trauma, infection, GA or operation, pain, stress, fever, burns and hypoglycaemia.

• At such times, there is normally raised adrenal corticosteroid production and the size of the response is proportional to the degree of stress.

ADRENOCORTICAL DISORDERS• Adrenocortical hyperfunction may lead to

release of excessive: 1. glucocorticoids (Cushing disease) 2. mineralocorticoids (Conn syndrome or

hyperaldosteronism) 3. androgens (congenital adrenal hyperplasia).

CUSHING DISEASE• Cushing disease is caused by excess aglucocorticoid

production by adrenal hyperplasia secondary to excess ACTH production by pituitary basophil adenomas.

• The most obvious feature is central obesity, affecting the abdomen and also the face (moon face). interscapular region (buffalo hump) and trunk, but with relative sparing of the limbs.

• Hypertension is common. Breakdown of proteins with conversion to glucose (gluconeogenesis) leads to hyperglycaemia and possibly diabetes mellitus, osteoporosis, muscle weakness, thinning of the skin, purpura and purplish skin striae .

• The diagnosis is confirmed by a raised plasma cortisol level and absence of the normal diurnal variation in cortisol levels, normally highest in the morning around 8.00 am and lowest at midnight.

• Another useful screening test is to measure plasma cortisol at 8.00–9.00 am after giving 1 mg dexamethasone orally at midnight to suppress the adrenal glands temporarily; in health, cortisol levels fall but in Cushing syndrome there is no such fall (low-dose overnight dexamethasone suppression test).

Dental aspects • Local analgesia is preferred for pain control. Conscious sedation

can be given, preferably with nitrous oxide and oxygen. GA must be carried out in hospital. Management complications may include:

1. the need for corticosteroid cover; patients, once treated, are maintained on corticosteroid replacement therapy and then are at risk from an adrenal crisis if subjected to operation, anaesthesia or trauma

2. hypertension3. cardiovascular disease4. diabetes mellitus 5. psychosis 6. vertebral collapse or myopathy causing limited mobility 7. multiple endocrine adenomatosis (MEA)

• There are no specific oral manifestations of Cushing disease, but patients have been referred for a suspected dental cause of the swollen face

HYPERALDOSTERONISM• Primary hyperaldosteronism (Conn syndrome) arises

from an adrenal cortex benign tumour or hyperplasia. • Secondary hyperaldosteronism arises from activation

of the renin–angiotensin system in cirrhosis, nephrotic syndrome, severe cardiac failure or renal artery stenosis.

• High aldosterone secretion leads to potassium loss (hypokalaemia) – causing muscle weakness and cramps, paraesthesia, polyuria and polydipsia, and, since it is associated with a metabolic alkalosis, may lead to tetany – and sodium retention (causing hypertension but rarely oedema).

• Amiloride, or the aldosterone antagonist spironolactone, is given until the affected adrenal gland can be excised.

• Dental aspects : - Local analgesia is used for pain control. Conscious

sedation may be helpful, especially if there is hypertension.

- GA must as always be carried out in hospital. In the untreated patient, hypertension and muscle weakness are the main complications.

-Competitive muscle relaxants may be dangerous, as they can cause profound paralysis.

- If bilateral adrenalectomy has been carried out, the patient is at risk from collapse during dental treatment and therefore requires corticosteroid cover.

ADRENOCORTICAL HYPOFUNCTION• Adrenocortical hypofunction is due most

commonly to adrenocorticotropic hormone (corticotropin) deficiency caused by the suppression of adrenocortical function following the use of systemic corticosteroids (secondary hypoadrenocorticism); occasionally by acquired adrenal disease (primary hypoadrenocorticism); and rarely, due to a congenital defect in corticosteroid biosynthesis (congenital adrenal hyperplasia)

Primary hypoadrenocorticism (Addison disease)• Primary hypoadrenocorticism is rare and caused by

autoantibodies to the adrenal cortex, causing adrenocortical atrophy and failed hormone secretion – cortisol (hydrocortisone) and aldosterone.

• Lack of cortisol predisposes to hypotension and hypoglycaemia, but stimulates the hypothalamopituitary axis causing release of pro-opiomelanocortin which has ACTH and melanocyte- stimulating hormone (MSH) activity and can cause hyperpigmentation.

• Lack of aldosterone leads to sodium depletion, reduced extracellular fluid volume and hypotension

• The lack of adrenocortical reserve makes patients vulnerable to any stress such as infection, trauma, surgery or anaesthesia, though they may be asymptomatic otherwise.

• An acute adrenal crisis (Addisonian crisis or shock) is thus characterized by collapse, bradycardia, hypotension, profound weakness, hypoglycaemia, vomiting and dehydration.

• Patients with hypoadrenocorticism also suffer from fatigue and weakness, lethargy, weight loss, anorexia, nausea, vomiting, diarrhoea, hyperpigmentation, dizziness and postural hypotension.

• Diagnosis of hypoadrenocorticism is confirmed by: hypotension; sometimes low plasma sodium and raised potassium; plasma glucose assay (hypoglycaemia is common); and low plasma cortisol levels and depressed cortisol responses to ACTH stimulation.

• In hypoadrenocorticism the basal plasma cortisol level is usually lower than 6 mg/100 ml.

• Most patients are treated with oral hydrocortisone and fludrocortisone.

• Dental aspects:• Conscious sedation should generally be

avoided unless the patient has had corticosteroid cover. GA is obviously a matter for the expert anaesthetist in hospital.

• Brown or black pigmentation of the mucosa is seen in over 75% of patients with Addison disease, but is not a feature of corticosteroid-induced hypoadrenocorticism or of hypoadrenocorticism secondary to hypothalamopituitary disease.

• Hyperpigmentation is related to high levels of MSH and affects particularly areas normally pigmented or exposed to trauma (e.g. in the buccal mucosa at the occlusal line, or the tongue, but also the gingivae

SYSTEMIC CORTICOSTEROID THERAPY

• Corticosteroids have a negative feedback control on hypothalamic activity and ACTH production and there is thus suppression of the HPA axis and the adrenals may become unable to produce a steroid response to stress. When the adrenal cortex is unable to produce the necessary steroid response to stress, acute adrenal insufficiency (adrenal crisis) can result, with rapidly developing hypotension, collapse and possibly death.

• Suppression of the HPA axis becomes profound if corticosteroid treatment has been prolonged and/or the dose of steroids exceeds physiological levels (more than about 7.5 mg/day of prednisolone). Adrenal suppression is less when the exogenous steroid is given on alternate days or as a single morning dose (rather than as divided doses through the day)

• However, adrenal function may even be suppressed for up to a week after cessation of steroid treatment lasting only 5 days. If steroid treatment is for longer periods, adrenal function may be suppressed for at least 30 days and perhaps for 2–24 months after the cessation of treatment.

• Patients on, or who have been on, corticosteroid therapy within the past 30 days may be at risk from adrenal crisis, and those who have been on them during the previous 24 months may also be at risk, if they are not given supplementary corticosteroids before and during periods of stress such as operation, GA, infection or trauma.

• Although the evidence for the need for steroid cover may be questionable, medicolegal and other considerations suggest that one should act on the side of caution and fully inform and discuss with the patient, take medical advice in any case of doubt and give steroid cover unless confident that collapse is unlikely.

Dental Aspects

• Adrenocortical function may be suppressed if: • the patient is currently on daily systemic corticosteroids at doses above 5 mg prednisolone

• corticosteroids have been taken regularly during the previous 30 days

• corticosteroids have been taken for more than 1 month during the past year.

• During intercurrent illness or infection, after trauma, or before operation or anaesthesia, these patients may require a higher steroid dosage.

• Steroid supplementation should be considered before stressful procedures. It is recognized that dentoalveolar or maxillofacial surgery may result in stress, but most other forms of dental treatment cause little response.

• The blood pressure must be carefully watched during surgery and especially during recovery, and steroid supplementation given immediately if the blood pressure starts to fall.

• Minor operations under LA may be covered by giving the usual oral steroid dose in the morning and giving oral steroids 2–4 h pre- and post-operatively (25–50 mg hydrocortisone or 20 mg prednisolone or 4 mg dexamethasone) or by giving intravenous 25–50 mg hydrocortisone immediately before operation.

• Intravenous hydrocortisone must be immediately available for use if the blood pressure falls or the patient collapses.

• Cover for major operations can be provided by giving at least 25–50 mg hydrocortisone sodium succinate intramuscularly or intravenously (with the pre-medication) and then 6-hourly for a further 24–72 h.

• Drugs, especially sedatives and general anaesthetics, are a hazard and it is extremely important to avoid hypoxia, hypotension or haemorrhage. Patients may also require special management as a result of diabetes, hypertension, poor wound healing or infections.

• Aspirin and other NSAIDs should be avoided as they may increase the risk of peptic ulceration.

• Topical corticosteroids for use in the mouth are unlikely to have any systemic effect but predispose to oral candidosis.

• Susceptibility to infection is increased by systemic steroid use and there is a predisposition to herpes virus infections (particularly herpes simplex).

• Passive immunization with varicella zoster immunoglobulin is indicated for non-immune patients on systemic corticosteroids (or who have been on them within the previous 3 months), if exposed to chickenpox or zoster. Immunization should be given within 3 days of exposure.

• Long-term and profound immunosuppression may lead to the appearance of hairy leukoplakia, Kaposi sarcoma, lymphomas, lip cancer or oral keratosis or other oral complications

SECONDARY ADRENOCORTICAL INSUFFICIENCY Secondary adrenocortical insufficiency can

also be caused by ACTH deficiency as a result of hypothalamic or pituitary disease. It is then associated with other endocrine defects, but no hyperpigmentation (ACTH levels are low) and blood pressure is virtually normal (aldosterone secretion is normal).

Adrenal Medulla

• The adrenal medulla secretes the catecholamines norepinephrine (noradrenaline) and epinephrine (adrenaline) in response to hypotension, hypoglycaemia and other stress, their release being regulated by the central nervous system.

PHAEOCHROMOCYTOMA

• Phaeochromocytomas are rare, usually benign tumours, most commonly in the adrenal medulla (producing epinephrine) but others arise in other neuroectodermal tissues such as paraganglia or the sympathetic chain and produce norepinephrine or dopamine.

• Typical features are episodes of anxiety, headache, epigastric discomfort, palpitations, tachycardia, arrhythmias, hypertension, sweating, pyrexia, flushing and glycosuria.

• Diagnosis is supported by finding excessive urinary catecholamines and their metabolites such as vanillylmandelic acid (VMA) or metanephrines.

• The tumour is excised after the blood pressure has been controlled with an alpha- blocking agent (e.g. phenoxybenzamine) and a beta-blocker.

• Dental aspects :• Acute hypertension and arrhythmias may

complicate dental treatment. • Elective treatment should therefore be

deferred until after surgical treatment of the phaeochromocytoma.

• If emergency care is required, the blood pressure should first be controlled with alpha- (such as phenoxybenzamine or prazosin) and then beta-adrenergic (such as propanolol) blockers.

• Patients who have had adrenal surgery may suffer from hypoadrenocorticism, since the adrenal cortex is inevitably damaged at operation. These patients therefore require steroid cover at operation.

• Local analgesia is then generally safe and epinephrine in modest amounts is unlikely to have any significant adverse effect. Conscious sedation may be desirable to control anxiety and endogenous epinephrine production.

• General anaesthesia must only be given in hospital; neuroleptanalgesia using a combination such as droperidol, fentanyl and midazolam may be the most satisfactory choice.