adrenal disorders Flashcards
addison’s disease what it is and most common cause
primary adrenal failure
TB= commonest worldwide
autoimmune =commonest UK
destroy adrenal cortex
symptoms addison’s
pigmentation
autoimmune vitiligo (patches of skin that lost colour)
no cortisol or aldosterone= low BP
what is POMC
Pro-opio-melanocortin
cleaved to become ACTH/aMSH(a-melanocyte stimulating hormone)
consequence of adrenocortical failure
low BP (postural hypotension)
hyponatraemia
hyperkalaemia
Low glucose due to glucocorticoid deficiency
High ACTH causing increased pigmentation
Eventual death due to severe hypotension
Tests for addison’s
biochemistry: low Na/high K
9am cortisol=low (ACTH=high)
short synACTHen test
give 250ug synacthen IM
measure cortisol response (no response=addisons)
treatment for primary adrenocortical failure - what needs replacing
-replace cortisol-
with hydrocortisone three times daily (10 + 5 + 2.5)
or
Prednisolone 3mg daily
-replace aldosterone
Fludrocortisone 50 to 100 mcg daily
-no need to replace adrenal sex steroid
what to replace aldosterone
fludrocortisone 50-100mcg daily
not aldosterone as half life too short for safe once daily administration
what does 11bHSD do and what does it stand for
11b-hydroxysteroid dehydrogenase
converts cortisol into cortisone(inactive) to protect aldosterone receptors (MR)
cause of cushing’s
taking too many steroids(glucocorticoids)
pituitary dependent cushing’s disease
ectopic ACTH from lung cancer
adrenal adenoma secreting cortisol
investigations for cushing’s
24hr urine collection for urinary free cortisol
blood diurnal cortisol level
low dose dexamethasone suppression test
how to do dexamethasone suppression test to test for cushing’s
dexamethasone=artificial glucocorticoid.
healthy- cortisol suppressed to zero.
cushing’s- failure to suppress cortisol
treatment for cushing’s drug list
metyrapone
ketoconazole
osilidrostat
metyrapone MOA, use , SE
MOA: inhibit 11b-hydroxylase
use: control symptoms prior to surgery + better post-op recover.
Control symptoms after radiotherapy.
SE: hypertension on LT use
hirsutism
ketoconazole MOA, use , SE
MOA: block 17a-hydroxylase- inhibit cortisol production
use: similar to metyrapone
control symptoms prior to surgery
SE: live damage- monitor liver function weekly, clinically and biochemically
osilidrostat MOA
MOA- block 11b + 17a hydroxylase- inhibit cortisol production
additional (more surgical treatment for cushing’s
Depends on cause
Pituitary surgery (trans-sphenoidal hypophysectomy)
Bilateral adrenalectomy
Unilateral adrenalectomy for adrenal mass
what is conn’s syndrome
Benign adrenal cortical tumour (zona glomerulosa)
Aldosterone in excess
effects of conn’s syndrome
Increases:
renal sodium reabsorption
renal potassium excretion
blood pressure
conn’s syndrome diagnosis
primary hyperaldosteronism
renin-angiotensin system should be suppressed
conn’s syndrome treatment
MR antagonist ie
spironolactone
epleronone
what spironolactone do: MOA and SE
MR antagonist
blocks sodium resorption+ potassium excretion in kidney tubules (potassium sparing diuretic)
SE:
gynaecomastia
epleronone- what is it
MR antagonist
similar affinity to spironolactone
less binding to androgen- better tolerated (less gynaecomastia)
phaeochromocytomas what is it
adrenal MEDULLA tumour
secrete catecholamines
(adrenaline and nor-adrenaline)
clinical features of phaeochromocytomas
(episodic/severe) Hypertension in young people (after abdominal palpation)
Severe hypertension can cause MI/stroke
High adrenaline can cause ventricular fibrillation + death
medical emergency
management of phaeochromocytomas
surgery-
careful with prep as anaesthetic can cause hypertensive crisis
1) Alpha blockade(alpha receptors on arteries cause vasoconstriction)
—plus IV fluid if needed
2) Beta blockade prevent tachycardia
