Endocrine 3 Flashcards
2 areas of adrenals?
inner medulla (neural crest origin) outer cortex (more glandular)
3 zones of cortex?
glomerulosa
fasciculata
reticularis
what for glomerulosa make?
aldosterone (mineralocorticoids)
what does fasciulata make?
glucocorticoids (eg cortisol)
what does reticularis make?
androgens
what does medulla make?
adrenaline
noradrenaline
where are most androgens made, what does this mean?
gonads
so adrenal problems foesnt really affect androgen function
what are cortex products derived from?
cholesterol
fasciculata hormones feed back to where?
pituitary (ACTH production)
where does glomerulosa hormones feed back to?
RAAS system (kidney??)
pathology causing lack of cortex hormones?
addisons disease (primary adrenal failure)
tumours (metastatic lung malignancy commonly)
TB
adrenal haemorrhage
haemochromatosis
what happens in addisons disease?
autoimmune destruction of all 3 zones of adrenal cortex
addisons phenotype?
pigmentation hair loss weight loss (cortisol is an anabolic hormone) postural hypotension hypoglycaemia diarrhoea lethargy
why does pigmentation occur in addisons?
pituitary produces ACTH to try and correct lack of cortisol from adrenals which also produces MSH as same pre-cursor
aldosterone function?
maintain high enough blood pressure by increasing reabsorption of sodium
causes potassium loss (sodium potassium pump)
addisons biochemistry?
hyponatraemia
hyperkalaemia
hypoglycaemia
addisons diagnosis (dynamic testing)?
synACTHen test
synthetic ACTH given at 0 mins, should cause a rise in cortisol to >550 at 1 hr
measure ACTH at time 0, in primary adrenal problem it will be eelvated or inappropriately normal
imaging in addisons?
CT
replacement in addisons?
hydrocortisone (20mg split into 3 times through day)
fludrocortisone (once daily)
main adrenal hormones which can be in excess?
aldosterone
cortisol
catecholamines
adrenal hormone deficiency usually affects all hormones, excess usually affects only one at a time, T/F?
true
Summarise RAAS?
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what is conns syndrome?
aldosterone excess (due to adenoma)
conns phenotype?
hypertension (aldosterone doesnt stop when BP is adequete so RAAS never switched off)
conns biochemistry?
hypokalaemia (K+ removed in exchange for Na+)
dont get hypernatraemia as water follows the Na+ so its normal concentration
how is conns confirmed?
aldosterone:renin ratio
(aldosterone will be high and low renin)
(body trying to stop production by stopping renin)
how can conns be confirmed with dynamic testing?
give lots of Na+ (generally given 2L of NaCl to drink in clinic) which will suppress RAAS in normal people but not in conns
imaging in conns?
CT
conns management?
surgery to remove adenoma
spironolactone - aldosterone antagonist (can cause gynaecomastia)
adrenal cushings biochem?
dexamethasone suppression test would give a low ACTH as its not a pituitary problem
adrenal cushings?
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what drug can be used in cushings if not fit for surgery?
mityrapone??
excess catecholamines (medulla hormones?
phaeochromocytoma (tumour involving chromaffin cells in adrenal medulla)
phaeochromocytoma phenotype?
headache
hypertension (episodic, sometimes hypotension, postural hypotension is common)
palpitations
sweating
phaeochromocytoma testing?
24 hr urinary metanephrines (breakdown products of adrenaline/noradrenaline)
how are catecholamines made?
synthesised from amino acid tyrosine
how is phaeochromocytoma managed?
surgery
need to give alpha blockers then beta blockers for 6 weeks before surgery with rehydration
why must you alpha block first?
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imaging in phaeochromocytoma?
CT
10% rule in phaeochromocytoma?
10% are bilateral
10% are malignant
10% are genetic
10% are extra-adrenal
nuclear medicine scan in phaeochromocytoma?
can tell whether functionally active and can look for metastases
uses adrenaline precursor MIBG
