Adrenal Disorders Flashcards by Sophie Pitcairn

What hormones does the medulla produce?

Norepinephrine and epinephrine

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What is the common approach for endocrine symptoms?

Clinical suspicion - test for assessing functional status - aetiology - if tumour - endocrine deficiency correction

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Describe the hypathalmo- hypopituitary axis

If under stress the hypothalamus produces CRH which acts on anterior pituitary to stimulate ACTH
This stimulates adrenal gland to release cortisol
There is a short and long negative feedback loop

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What enzyme is important in producing cortisol and aldosterone?

21-hydroxylase

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What are 3 adrenal disorders leading to hypofunction?

Adrenal destruction - most common
Adrenal Dysgenesis
Impaired steroidogenesis

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What disease causes primary adrenal insufficiency?

Addison’s disease - autoimmune destruction, invasion, infiltration, infection, iatrogenic

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What causes adrenal enzyme defects?

Congenital adrenal hyperplasia - 21 hydroxylase deficiency

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Describe autoimmune Addison’s disease

Positive adrenal autoantibodies
Lymphocytic infiltrate of adrenal cortex
Associated autoimmune diseases are common
More than 85% of adrenal failure

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What are some common symptoms associated with primary adrenal failure?

Weakness, fatigue, weight loss
Skin pigmentation or vitiligo
Hypotension
Unexplained vomiting and diarrhoea
Salt craving
Postural symptoms

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What are some possible clue to diagnosis of adrenal failure?

Disproportional between severity of illness and hypotension/ dehydration
Unexplained hypoglycaemia
Other endocrine features
Previous depression or weight loss

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How is adrenal insufficiency diagnosed?

Bloods - U+E, glucose and FBC (low Na and high K)
Random cortisol (>450nmol/l adrenal status uncertain)
Synacthen test - 250mg of tetracosactin IM or IV (ACTH)

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What tests should be done is adrenocortical insufficiency suspected?

Rapid ACTH stimulation test
If normal then excludes primary
If abnormal then Plasma ACTH
If elevated then primary
If supressed then secondary

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Describe glucocorticoid replacement

Hydrocortisone (20-30mg), prednisolone and dexamethasone
Given in divided doses to mimic normal diurnal variation - more given in morning

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Describe mineralocorticoid replacement

Synthetic steroid - fludrocortisone
Binds to mineralocorticoid (aldosterone) receptors
50-300 mg daily
Adjust dose according to clinical status, U+E and plasma renin level

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Who needs special care when treating hypofunction?

Hypo-adrenal patients on replacement steroids
Patients on steroids
Patients who have received previous 18/12 treatment

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What happens to treatment if minor short lived illness or stress?

Double glucocorticoid dose

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What happens to treatment if major illness or operation?

100mg hydrocortisone IV stat
50-100 HC via IV every 8hrs

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What are the 3 self acre rules for patients on steroids?

Never miss steroid dose
Double hydrocortisone dose in event of intercurrent illness
If severe vomiting or diarrhoea then call for help

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What are some causes of primary hyperaldosteronism?

Unilateral adenoma and bilateral hyperplasia

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What are some rarer endocrine causes for hypertension?

Pheochromocytoma, Cushing’s, acromegaly, hyperparathyroidism, hypothyroidism and congenital adrenal hyperplasia

What causes hypersecretion from cortex of adrenal gland?

Cushing’s syndrome - cortisol and androgens
Conn’s syndrome - aldosterone

What is a cause of hypersecretion from medulla of adrenal gland?

Pheochromocytoma - catecholamines

What are the side effects of Cushing’s syndrome?

Weakness of skin, muscle and bone
Hypertension and heart failure
Diabetes mellitus

Describe Cushing’s syndrome

Excess corticosteroids
Cortisol is a catabolic hormone so can cause tissue breakdown, sodium retention and insulin antagonism
Also immune system suppression

What are some signs of Cushing's syndrome?

Central obesity, proximal weakness, easy bruising, hypertension, purple striae, oedema, thin skin, and moon face

What can cause ACTH dependant or independent Cushing's disease?

Dependent - pituitary tumour or ectopic ACTH secretion Independent - adrenal tumour

What is the approach to hypersortisolism?

Overnight Dex test or 24hr urine free cortisol to screen and confirm To see if ACTH dependent - paired morn midnight ACTH cortisol To see if pituitary or not then high Dex test MRI and CT for localisation

What is the normal range for 24hr urinary free cortisol?

14-135 nmol/24hr

What is the treatment for Cushing's syndrome?

Surgery to remove causative tumour Medical RT Bilateral adrenalectomy

What is the medical treatment for Cushing's syndrome?

Adrenal hormone synthesis inhibitors - ketoconazole and Metyrapone Destroy adrenocortical cells - mitotane

Describe Conn's syndrome

Aldosterone excess production Adenoma or bilateral hyperplasia Aldosterone - water and sodium retention and K excretion

Describe the pathophysiology of primary hyperaldosteronism

Aldosterone producing tumour increases blood volume, blood pressure and urine K+ Renin gives angiotensinogen then angiotensin I then II So increased Aldosterone and decreased renin

What is the screening for hyperaldosteronism?

Plasma PA/PRA ration Primary hyperaldosteronism - Ratio is over 20 Secondary or essential - Ratio is under 20

What are 2 signs of hyperaldosteronism?

Hypertension and hypokalaemia

What does decreased plasma renin activity and increased aldosterone conc. suggest?

Primary hyperaldosteronism

What does increased PRA and PAC suggest?

Secondary hyperaldosteronism

What does decreased PRA and PAC suggest?

Congenital adrenal hyperplasia Cushing's syndrome DOC producing tumour

What is the conformation test for hyperaldosteronism?

24hr urine aldosterone . 12 ug/day Urinary sodium >200mEq During 4 days of salt loading

What tests help to establish aldosterone source?

CT scan of adrenal glands Upright posture test Plasma 18-hydroxycorticosterone

Describe pheochromocytoma

Rare tumour of adrenal glands producing too much catecholamines - norepinephrine and epinephrine Get hypertension, headache, sweating, palpitations, tremor, pallor and anxiety (paroxysmal attacks)

What are some types of pheochromocytoma?

MEN II MEN III Von Hippel Landau Syndrome

How is a suspected pheochromocytoma investigated?

24 hr urine - total metanephrines and catecholamines If normal then re check later If 2 fold elevation then CT/MRI for localisation Also consider 123-IMIBG scan

What is tested for in pheochromocytoma - genetic testing?

PHEOs/ PGLs - this leads to the metabolic problem giving tumour growth

What is the preoperative preparation for removal of pheochromocytoma?

Non selective alpha blocker Beta blockers may also be needed When trying to take tumour out - if touched could release large amounts of catecholamines into bloodstream

What test should be done if there is clinical suspicion of adrenal mass?

Free metanephrine in plasma or urine 1mg Dexamethasone suppression test If hypertension then K and ALD/PRA ratio

How is an adrenal mass tested to see if malignant or benign?

Unenhanced CT Chemical shift MRI Then delayed enhanced CT Surgery if malignant and if benign surgery depends on size (>6cm)

Why does a deficit in 21-hydroxylase cause adrenal hyperplasia?

Lack of enzyme inhibits synthesis of cortisol So removes negative feedback on ACTH and CRH Increased ACTH secretion is responsible for enlargement

Describe congenital adrenal hyperplasia

90% of cases are 21 hydroxylase deficiency Severe cases - neonatal salt losing crisis and ambiguous genitalia Incomplete - hirsutism and pseudo-precocious puberty