Adrenal disorders Flashcards
How does the adrenal gland develop embryologically?
Fetal medulla becomes encapsulated by fetal cortex
What is hyperaldosteronism?
Excess production of aldosterone by zona glomerulosa in adrenal glands
How are the causes of hyperaldosteronism categorised? What do they mean?
Primary - problem with adrenal cortex
Secondary - overactivity of RAAS
What are the causes of primary hyperaldosteronism? Which is the most common?
Bilateral idiopathic adrenal hyperplasia - most common
Conn’s syndrome
What is Conn’s syndrome?
Adrenal adenoma
secretes aldosterone
What are the causes of secondary hyperaldosteronism?
Renal artery stenosis
Renin producing tumour e.g juxtaglomerular tumour
How do you differentiate between primary and secondary hyperaldosteronism?
Primary
low renin levels
high aldosterone:renin ratio
Secondary
high renin levels
low aldosterone:renin ratio
What are the signs of hyperaldosteronism?
Hypertension
Hypernatraemia
Hypokalaemia
LV hypertrophy
How is hyperaldosteronism treated?
Conn’s syndrome - adrenal adenoma removed by surgery
Bilateral idiopathic adrenal hyperplasia + overactivity of RAAS - spironolactone
What does spironolactone do?
Mineralocorticoid receptor antagonist
What is Cushing’s syndrome?
Increased secretion of glucocorticoid cortisol
How are the causes of Cushing’s syndrome categorised?
External causes
Endogenous causes
What is the external cause of Cushing’s syndrome?
Prescribed glucocorticoids
What are the endogenous causes of Cushing’s syndrome?
Cushing’s disease
Adrenal Cushing’s
Non pituitary-adrenal tumours producing ACTH or CRH
What is Cushing’s disease?
Pituitary adenoma
secretes ACTH
What is Adrenal Cushing’s?
Adrenal tumour
produces excess cortisol
What is an example of a non pituitary-adenoma tumour that produces ACTH or CRH?
Small cell lung cancer
How do you differentiate between Adrenal cushing’s and Cushing’s disease/non pituitary-adrenal tumour?
Adrenal cushing’s - low ACTH
by negative feedback from excess cortisol
Cushing’s disease/non pituitary-adrenal tumour - high ACTH
being secreted by the tumour
What is the most common cause of Cushing’s syndrome?
What is the most rare cause?
Most common - external cause, prescribed glucocorticoids
Most rare - endogenous causes, non pituitary-adenoma tumour secreting ACTH or CRH
What are the signs and symptoms of Cushing’s syndrome?
Round pink face
Abdominal obesity
Buffalo hump
Skinny arms and legs
Purple striae on abdomen
Hypertension
Hyperglycaemia
What causes the pink round face in Cushing’s syndrome?
Redistribution of fat to face
What causes the abdominal obesity in Cushing’s syndrome?
Resdistribution of fat to abdomen
What causes the buffalo hump in Cushing’s syndrome?
Redistribution of fat to dorso-cervical fat pads
What causes the purple-striae on the abdomen in Cushing’s syndrome?
Cortisol stimulates proteolysis
proteins in skin break down, skin becomes thinner
leading to easy bruising
What causes the skinny arms and legs in Cushing’s syndrome?
Cortisol stimulating proteolysis in muscles
get wasting of muscles
What causes the hypertension in Cushing’s syndrome?
High levels of cortisol
may bind to aldosterone receptors
gives sodium and water retention
What causes the hyperglycaemia in Cushing’s syndrome?
Excess cortisol over-stimulates gluconeogenesis in liver
How is Cushing’s syndrome treated?
External causes - reduce dosage gradually, don’t stop suddenly
Endogenous causes - surgically remove the tumour
What is Addisons’s disease?
Condition of chronic adrenal insufficiency
What are the causes of Addison’s disease? Which is the most common cause?
Autoimmune destruction of adrenal cortex - most common cause
Infection - TB, fungal
Infiltration - amyloid, haemachromatosis
Malignancy
Genetic - congenital adrenal hyperplasia
Vascular - haemorrhage, infarction
Iatrogenic - adrenalectomy, drugs
What are the symptoms and signs of Addison’s disease?
Lethargy
Anorexia
Weight loss
Postural hypotension - dizziness
Increased skin pigmentation
Hypoglycaemia
Why is there increased skin pigmentation in Addison’s disease?
Decreased cortisol
reduced negative feedback on anterior pituitary
increased production of ACTH
requires POMC
broken down into ACTH and MSH (melanocyte stimulating hormone)
MSH binds to melanocrotin receptors on melanocytes
ACTH itself can bind to these and contribute
How is Addison’s disease treated?
Lifelong glucocorticoid replacement e.g. hydrocortisone
Lifelong mineralocorticoid replacement e.g. fludrocortisone
How can Addisonian’s crises be prevented?
Increase dose of glucocorticoid replacement at times of stress e.g. illness
because cortisol would naturally increase
If vomiting, use injection instead of tablets
because can’t absorb tablets
What is an Addisonian crisis?
Life-threatening emergency
caused by adrenal insufficiency
What can trigger an Addisonian crisis?
Severe stress
- trauma
- infection
- over exertion
- abrupt steroid drug withdrawal
Why do Addisonian crises occur?
Cortisol is too low to cope with the stress
What are the signs and symptoms of Addisonian crisis?
Nausea, vomiting
Fever
Hypotension
Vascular collapse
How is Addisonian’s crisis treated?
Rehydration with fluids
IV hydrocortisone - cortisol replacement
Correction of hypoglycaemia
What inheritance pattern does congenital adrenal hyperplasia show?
Autosomal recessive
What is the cause of congenital adrenal hyperplasia?
Defect in 21-hydroxylase enzyme
What are the consequences of a lack of the enzyme 21-hydroxylase?
Low glucocorticoids e.g. cortisol
Low mineralocorticoids e.g. aldosterone
High androgens e.g. testosterone
pathway redirected to here
How does congenital adrenal hyperplasia present?
Hypoglycaemia
Hypotension
Hyponatraemia
Hyperkalaemia
Virilisation - male characteristics
ambiguity of genitalia
How is congenital adrenal hyperplasia managed?
Treat addisonian crisis
Long term replacement of glucocorticoids, mineralocorticoid
Determine sex of baby
What is a phaeochromocytoma?
Tumour of the adrenal medulla chromaffin cells
secretes catecholamines, mainly noradrenaline
What is a paraganglioma?
Extra-adrenal tumour
chromaffin tissue origin
What are the symptoms of phaeochromocytoma and paraganglioma?
Severe hypertension
Palpitations
arrythmias
Diaphoresis - excessive sweating
Hyperglycaemia
Weight loss
Headaches
How are phaeochromocytomas and paragangliomas managed?
Alpha blockers - phenoxybenzamine
Beta blockers
In which order should alpha and beta blockers be given? Why?
Alpha before beta
Because otherwise get vasoconstriction only, makes hypertension worse
What tests are done when an adrenal hormone deficiency is suspected?
Electrolytes
9am cortisol
Stimulation test
What is the stimulation test for cortisol deficiency?
Inject synthetic ACTH, called synacthen
Cortisol should increase in response
What are the test results when there is an adrenal hormone deficiency?
Electrolytes - hyponatraemia, hyperkalaemia
9am cortisol - low
Stimulation test - cortisol remains low
What are the tests done when an adrenal hormone excess is suspected?
Electrolytes
Midnight cortisol
Suppression test
What is the suppression test for excess cortisol?
Give dexamethasone steroid drug
Should negatively feedback on anterior pituitary, decreasing ACTH secretion
Cortisol should decrease
What are the test results when there is an adrenal hormone excess?
Electrolytes - hypernatraemia, hypokalaemia
Midnight cortisol - high when it should be low
Suppression test - cortisol remains high
What tests are done to assess adrenal medulla function?
24h urine catecholamimes e.g. adrenaline, noradrenaline
24h urine metanephrines
Plasma metanephrines
What are metanephrines?
Metabolites of adrenaline and noradrenaline
Called metadrenaline and normetadrenaline
What are the test results of adrenal medulla function with phaeochromocytoma?
24h urine catecholamines - high
24h urine metanephrines - high
Plasma metanephrines - high
What scans are done to look for adrenal tumours?
CT scan
MRI scan
PET scan
What are the causes of adrenal hormone deficiency?
Addison’s disease
ACTH deficiency from hypopituitarism
Steroid induced ACTH suppression
What are the symptoms of ACTH deficiency?
Similar to primary adrenal failure - Addison’s disease
Except no hyperpigmentation as ACTH not raised
No hyperkalaemia as no mineralocorticoid deficiency
Hyponatraemia due to reduced cortisol meaning reduced diuresis
What are some examples of steroid drugs that suppress ACTH?
Dexamethasone
Prednisolone
What are steroid drugs used to treat?
Inflammatory disorders
- asthma
- inflammatory bowel disease
- rheumatoid arthritis
Suppress immune response to organ transplantation.