Adrenal Disorders Flashcards
What is the adrenal gland made up of?
Cortext
Medulla
Where is the capsule of the gland?
Outside of the gland
What are the three zones in the cortex?
Zona glomerulosa
Zona fasiculata
Zona reticularis
What are the cells in the medulla?
Chromaffin cells
Where are mineralocorticoids made?
Zona glomerulosa
What is an example of a mineralocorticoid?
Aldosterone
What regulate the zona glomerulosa?
Potassium
Where are glucocortioids made?
Zona fasciculata
What regulates the zona fasciculata?
ACTH
What is an example of a glucocorticoid?
Cortisol
What is made in the zona reticularis?
Adrenal androgens
What regulates the zona reticularis?
ACTH
Where is adrenaline made?
Medulla
What is on the top of the cortext?
Capsule
What is the rate limiting step in the synthesis of production of aldosterone?
Cholesterol to pregnenolone
What regulates aldosterone?
Renin-angiotensin system
Which organ regulates cortisol?
Hypothalamus
Which hormone does the hypothalamus release?
Corticotropin releasing hormone
Where does CRH act on?
Anterior pituitary
What does the anterior pituitary produce?
ACTH
Where does ACTH act on?
Adrenal cortext
Which part of the adrenal cortext does cortisol come from?
Zone fasciculata
When is cortisol at the peak?
9AM
What hormone is released when blood pressure falls?
Renin
Where does renin act?
Acts on angiotensinogen to produce more angiotensin I
What converts angiotensin 1 to angiotensin 2?
Angiotensin converting enzyme (ACE)
Where does angiotensin II act upon?
Adrenal cortex to product aldosterone
Also causes a direct vasoconstriction - increases BP
How does aldosterone cause a rise in BP?
Causes salt retention
Where is the receptor for steroids?
Intracellular.
Why might Cushing’s syndrome induce diabetes?
Excess cortisol increases blood sugar
Why might Cushing’s induce infection?
Decreased leukocyte migration due to reduced capillary dilation
Where are mineralocorticoid receptors located?
Kidneys
Salivary glands
Gut
Sweat glands
Why is hyperpigmentation in Addison’s disease?
Too much ACTH which breaks down into MSH which causes pigmentation
Where is the pigmentation in Addison’s disease most prominent?
Skin folds and creases
Buccal mucosa
What biochemistry points to Addison’s?
Decreased Na+
Increased K+
Hypoglycaemia
Does Addison’s have too much cortisol or too little?
Too little.
An adrenal insufficiency
What other autoimmune diseases are associated with Addison’s?
DM1
Pernicious anaemia
Autoimmune thyroiditis
What are the clinical features of Addison’s?
Anorexia and wt loss Fatigue Low BP Abdo pain D&V Hyperpigmentation
Which tests are done to confirm Addison’s?
Synacthen test.
Adrenal antibodies
Why does increased ACTH mean reduced cortisol?
Negative feedback loop.
Too much ACTH cuts out the adrenal cortex from producing cortisol
How is adrenal insufficiency managed acutely?
IV hydrocortisone
What is given as an aldosterone replacement?
Fludrocortisone
Why might steroids cause secondary adrenal insufficiency?
Too much cortisol turns off negative feedback therefore lack of ACTH
What is Cushing’s syndrome?
Excess cortisol secretion
What are the symptoms of Cushing’s syndrome?
Buffalo hump Moon face Central obesity Abdominal striae Skin atrophy Proximal myopathy
What is the primary cause of Cushing’s syndrome?
Pituitary adenoma
What is the definitive diagnostic test for Cushing’s syndrome?
Low dose dexamethasone suppression test.
What is involved in the low dose dexamethasone suppression test?
0.5mg every 6 hours for 48 hours.
Should be able to suppress below 50
What is the commonest cause of Cushing’s syndrome?
Steroids of any kind
What is the treatment of Cushing’s?
Long term steroids which cannot be stopped suddenly
When will extra doses of steroid be required for Cushing’s syndrome?
When ill or when having surgery
What does hypertension and hypokalaemia point towards?
Conn’s syndrome.
What is Conn’s syndrome?
Primary hyperaldosteronism
What is the name of the potassium channel which is common in Conn’s syndrome?
KCNJ5
What is the most common cause of Conn’s syndrome?
Adrenal adenoma
When is surgical removal of the adenoma not appropriate?
If bilateral adenomas
How is aldosterone excess confirmed?
Aldosterone:renin ratio
What is the commonest cause of a congenital adrenal hyperplasia?
21 alpha hydroxylase deficiency
There are higher levels of testosterone in congenital adrenal hyperplasia. What does this cause?
Phallic enlargement
Early development of pubic hair
Which hormones are not made in congenital adrenal hyperplasia?
Aldosterone
Cortisol
What is phaechromocytoma?
Tumour which produces catecholamine within the adrenal medulla
What are common symptoms of phaechromocytoma?
Headaches
Sweating
Palpitations
Hypertension
What biochemical abnormalities may be present in phaechromocytoma?
Hyperglycaemia
Low potassium
High haematocrit
Which scanning is sensitive only for phaechromocytomas?
MIBG scan
What reproductive abnormality is important to recognise in congenital adrenal hyperplasia?
Ambiguous genitalia
What does the angiotensin:renin ratio need to be before Conn’s can be diagnosed?
Over 750
What diagnostic test is done for Conn’s?
Saline suppression test.
2 litres of saline over 4 hours
What result from saline suppression can confirm Conn’s?
Aldosterone levels should fall by 50% if normal
How is Conn’s syndrome treated?
Surgical excision
What if there is a bilateral adrenal hyperplasia?
Surgical excision should be avoided and spironolactone given instead
What can be given if spironolactone cannot be tolerated
Eplerenone
What kinds of ectopic cancers can cause Cushing’s?
Lung, thymus or pancreas can release ACTH and cause increase in cortisoll
Why might libido decrease in Cushing’s?
ACTH also controls zona reticularis which controls sex hormones.
Which pro-hormone is made in the zona reticularis?
DHEA
Which cardiac receptors are acted on by adrenaline?
B1
If B1 receptors are activated what is the action?
Increased heart rate and force
Which vascular receptors are acted on by adrenaline?
alpha 1
If alpha 1 receptors are activated what is the action?
Vasoconstriction
True or False
Polyuria is unusual in phaechromocytoma
False.
Increased adrenaline means more gluconeogenesis and less insulin use so polyuria common
Which genetic disorder is phaechromocytoma linked with?
MEN2
How is phaechromocytoma treated?
Surgical removal of tumour
What other treatment should be given in phaechromocytoma?
Alpha and beta blockers