4 - adrenal Flashcards
what hormones are secreted where in adrenal glands?
adrenal medulla:
chromaffin cells= secrete adrenaline & noradrenaline
adrenal cortex:
zona glomerulosa = mineralocorticoids (aldosterone)
zona fasciculata = glucocorticoids (cortisol + corticosterone)
zona reticularis = androgens (testosterone)
what are the hormones of adrenal cortex all made from?
cholesterol as a basic 1st step for all of them - they go through different pathways
what is different about aldosterone regulation?
not regulated by hypothalamus or anterior pituitary stuff - by RAAS pathway
*reminder RAAS increases BP, increases Na and lowers K+
what is RAAS pathway?
renin released from kidneys which converts angiotensinogen to angiotensin I
angiotensin I converted to angiotensin II by ACE
angiotensin II tells adrenal gland to make aldosterone which increases BP, increases Na, lower K+
what is addison’s disease?
primary adrenal insufficiency = autoimmune destruction of adrenal cortex meaning low cortisol + low aldosterone
what is presentation of addison’s disease? biochem results?
- anorexia & weight loss
- fatigue & lethargy
- dizziness & low BP
- abdominal pain, vomiting, diarrhoea
- skin pigmentation (from high ACTH)
biochem results = low Na, high K, hypoglycaemia (in kids)
what is diagnostic test for addison’s?
short synacthen test (when give synthetic ACTH which should make cortisol above 250 but in addison’s above 550 = super high)
what would renin & aldosterone levels be like in addison’s? symptoms of this?
high renin, low aldosterone
*patients really crave salt
what is treatment of adrenal insufficiency? (like addison’s etc)
*if acute and also for chronic ongoing management
if acute = urgent hydrocortisone!!, 15-30mg
for chronic aldosterone replacement = fludrocortisone
what are important SICK day rules for adrenal insufficiency?
*in adrenal insufficiency they take fludrocortisone (to replace aldosterone)
- when ill, we use loads more cortisol so need to double the fludrocortisone
- if severely ill then need IV hydrocortisone throughout illness
*basically just need to remember to properly replace cortisol and aldosterone when ill and if pregnant etc. they should always carry medical alert badge
what is treatment if adrenal crisis?
adrenal crisis = life threatening emergency!!
give immediate IV hydrocortisone 100mg and 0.9% saline (then replace electrolyte)
*if in doubt = TREAT!!
what is secondary adrenal insufficiency? most common cause? treatment?
adrenal glands not making enough hormones because of problem further up line in pituitary or hypothalamus
steroids = most common cause
treat = hydrocortisone (cortisol replacement)
*don’t need aldosterone replacement as regulated through RAAS, nothing to do with pituitary & hypothalamus
what does fludrocortisone and hydrocortisone replace?
fludrocortisone = replaces aldosterone
hydrocortisone = replaces cortisol
what is primary hyperaldosteronism?
= autonomous production of aldosterone independent of regulation by RAAS e.g. makes too much aldosterone (which means increased BP, increased Na, decreased K)
what are the causes of primary hyperaldosteronism?
- Conn’s syndrome (adrenal adenoma) - genetic, 30%
- bilateral adrenal hyperplasia - idiopathic (most common cause - 60%)
what are clinical features of primary hyperaldosteronism? bad side effects of too much aldosterone?
- significant hypertension (think since high aldosterone means lots RAAS pathway so makes higher bp)
- hypokalaemia (keep thinking RAAS since maintains Na and excretes K+)
- compensatory metabolic alkalosis
*too much aldosterone = LV hypertrophy, increased risk of atheroma
what is steps to diagnosis of primary hyperaldosteronism?
- measure renin and aldosterone ratio (positive diagnosis would be too much aldosterone to renin)
- saline infusion test (positive test would be remained high aldosterone)
- confirm subtype of primary hyperaldosteronism by adrenal CT to check for adenoma
what is management of primary hyperaldosteronism?
if conn’s syndrome - unilateral adrenal adenoma = surgery
if bilateral adenoma or bilateral adrenal hyperplasia then mineralocorticoid antagonists like spironolactone or eplerenone (block aldosterone receptors)
what is congenital adrenal hyperplasia?
inherited group of disorders, characterised by deficiency in different enzymes necessary for cortisol synthesis
*each different type is deficient in different enzymes. because of the pathways and way hormone production works, lack of cortisol + aldosterone can mean excess androgen
most common deficiency = 90% from autosomal recessive 21 ⍺-hydroxylase deficiency
how does classical congenital adrenal hyperplasia present?
presents at birth, genital ambiguity, adrenal failure, poor weight gain, hypoglycaemia, hypokalaemia
how does non classical congenital adrenal hyperplasia present?
presents later, precocious puberty, hirsutism, acne, oligomenorrhea, infertility
how to investigate & diagnose congenital adrenal hyperplasia?
- basal or stimulated 17-OH progesterone (21 hydroxylase usually helps make cortisol, 17-OH progesterone is further up in steps and when 21 hydroxylase not there then cortisol can’t be made so 17-OH progesterone builds up. high levels = positive diagnosis)
- genetic analysis
what is management of congenital adrenal hyperplasia?
a) in paediatric
b) in adults
a) glucocorticoid replacement, surgical correction, try achieve max growth
b) glucocorticoid replacement, control androgen excess (to help fertility)
what is phaeochromoctyoma?
rare tumour of adrenal medulla, difficult to diagnose as lots of general symptoms and rare diagnosis (means high catecholamines since in medulla)
*can also get extra tumour - paraganglioma (anywhere in ganglion)
what is presentation of phaeochromocytoma?
- labile hypertension (random spikes of high BP)
- postural hypotension (normal BP when sitting but sometimes go super high, sometimes super low)
- paroxysmal sweating
- headache
*also pallor, tachycardia, inner anxiety, constipation, weight loss
why is diagnosis of phaeochromocytoma important?
high morbidity associated and lots of complications:
- LV hypertrophy
- myocardial necrosis
- stroke
- shock
- paralytic ileus of bowel
what are biochemical abnormalities seen in phaeochromocytoma?
- high adrenaline (which causes hyperglycaemia)
- low K+
- high Hb concentration
- mild hypercalcaemia
- lactic acidosis
what is steps to diagnosis of phaeochromocytoma?
- confirm catecholamine excess
- 24hr urinary metanephrines = 24hr urine collection (loads of drugs, diet etc can give false positive)
- plasma metanephrine = if urine not worked, increased specificity
- can then do CT scan - chest, abdomen, pelvis (to look for paraganglioma’s)
- MIBG scan
what is management of phaeochromocytoma?
definitive management = surgery (laparoscopic - need total excision & chemo if malignant or metastases)
pharmacological treatment until surgery:
a before b!!
- alpha blocker e.g. phenoxybenzamine or doxazosin (to prevent cardiac instability)
- beta blocker, after alpha, if still needed e.g. propranolol, atenolol, metoprolol
*if 2 at same time can get severe side effects
- high salt diet
- high fluid
→often feel unwell in this but good as need to be high fluid before surgery to prevent hypotension/hypovolaemia