adrenal physiology Flashcards by Meg R

causes of primary insufficiency

addison’s disease
congenital adrenal hyperplasia (CAH)
adrenal TB/malignancy

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secondary (and tertiary) insufficiency

due to lack of ACTH stimulation
iatrogenic (excess exogenous steroid)
pituitary/hypothalamic disorders

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clinical features of addison’s disease

anorexia, weight loss
fatigue/lethargy
dizziness and low BP
abdominal pain, vomiting, diarrhoea
skin pigmentation

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commonest cause of PAI ?

addison’s

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cause of addison’s

autoimmune destruction of adrenal cortex (90% destrtoyed before symptomatic, autoantibodies positive in 70%)

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what other autoimmune diseases associated w/ addison’s ?

T1DM, autoimmune thyroid disease, pernicious anaemia

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diagnosis of adrenal insufficiency

“suspicious biochemistry” (decrease Na, increase K) (hypoglycaemia)

“short synacthen test” (measueing plasma cortisol before and 30 mins after IV/IM ACTH injection)

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what are ACTH levels in addison’s ?

should be high (causes skin pigmentation)

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renin/ aldosterone levels in addisons ?

inc renin dec aldosterone

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management of adrenal insufficiency

hydrocortisone as cortisol replacement
(iv first if unewell, usually 15-30mg daily in divided doses, try to mimic diurnal rhythm)

fludrocortisone as aldosterone replacement
(careful monitoring of BP and K)

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adrenal crisis management

fluids - normal saline
100mg iv - steroids hydrocortisone 50mg IM every 6hrs or 24hr infusion
treat underlying cause

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secondary adrenal insufficiency (lack or CRH/ACTH) causes

pituitary/hypothalamic disease, tumours
(surgery/radiotherapy to manage)

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more of a tertiary adrenal isufficiency

exogenous steroid use

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secondary adrenal insufficiency (lack or CRH/ACTH) clinical features

pale skin (no increase ACTH)
aldosterone production intact (regulated by RAS)

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SAI treatment

trear w/ hydrocortisone replacement (fludrocortisone unnecessary)

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cushing’s syndrome

excess cortisol secretion
high mortality

clinical features of cortisol excess

easy bruising
facial plethora
striae
proximal myopathy

endogenous cause of cushings

ectopic
ACTH independent (too much cortisol) adenoma, adrenal carcinoma

diagnosing cushing’s

establishing cortisol excess
overnight dexamethasone suppression test
24hr urinary free cortisol
late night salivary cortisol
low dose dexamethasone suppression test
repeat to confirm

diagnostic test for cushings syndrome

low dose dexanthesone suppresion ACTH and cortisol measured base line and 24hrs (2mg per day)

what is the commonest cause of cortisol excess

iatrogenic cushing’s syndrome

iatrogenic cushing syndrome happens due to…

prolonged high dose steroid therpay (asthma, RA, IBD, transplants)
chronic suppression of pituitary ACTH production and adrenal atrophy

adrenal suppression

atrophy of adrenal cortex

implications of adrenal suppression

unable to response to stress(illness, surgery)
need extra doses of steroid when ill/surgical procedure
cannot stop suddenly
gradually withdrawal of steroid therapy (if >4-6 weeks)

what are the endocrine causes of hypertension ?

too much aldosterone too much GH too much adrenaline and noradrenaline

hypertension and hypokalaemia raises the possibility of...?

primary aldosteronism

primary aldosteronism reflects...

autonomous production of aldosterone independent of its regulators (angiotensin II/potassium)

what appearance would sample have ?

fleshy appearance

what is commonest secondary cause of hypertension

primary aldosteronism (up to 10% of cases, 20% resistant hypertension)

clinical features of primary alodsteronism

significant hypertension hypokalaemia (in around 30%) alkalosis

subtypes of primary aldosteronism

adrenal adenoma (conn's syndrome) bilateral adrenal hyperplasia (commonest cause) rare causes (genetic mutations, unilateral hyperplasia)

diagnosing primary aldosteronism

1. confirm aldosterone excess measure plasma aldosterone and renin and express as ratio (ARR-aldosterone to renin ratio) 2. confirm subtype adrenal CT to demonstrate adenoma sometimes adrenal vein sampling to confirm adenoma is true source of aldosterone excess

management of PA

surgical (only if clear) - unilateral laparoscopic adrenalectomy ONLY IF ADRENAL ADENOMA (and excess confrimed in adrenal vein sampling) - cure of hypokalaemia - cures hypertension in 30-70% cases medical - in bilateral adrenal hyperplasia - use MR antagonists (spironolactone)