Adrenal gland Flashcards
what is produced in the zona glomerulosa
mineralocorticoids
what is produced in the zona fasiculata
glucocorticoids
what is produced in the zona reticularis
androgens
what cells are present in the adrenal medulla and what do they secrete
chromaffin cells
catecholamines
describe how cholesterol becomes testosterone
synthesised to aldosterone, cortisol or DHEA/androstenedione, converted to testosterone
this is done by many individual enzymes
regulation of cortisol and androgen synthesis?
hypothalamus recieves stress, time of day, illness to release CRH to ant pituitary
releases ACTH to cause cortisol production in adrenal
-ve feedback of cortisol on hypothalamus and ant pituitary
describe the peak of cortisol
diurnal variation
highest at 6-10am and drops over the day before it is near zero at night
describe regulation of aldosterone synthesis?
decreased BP leads to renin activation, angiotensinogen to ATI, converted to ATII by ACE, causes direct vasoconstriction and aldosterone to increase Na retention in kidneys to decrease fluid output
6 classes of steroid receptor
glucocorticoid mineralocorticoid vitamin D androgen oestrogen progestin
effects of cortisol
increases blood sugar, lipolysis and proteolysis
decreases cytokines, macrophage activity, leucocyte migration
accelerated osteoporosis
decreased libido
euphoria/psychosis
increased BP, CO, renal blood flow and GFR
what target tissues does aldosterone act on
kidneys
salivary glands
sweat glands
gut
causes of primary adrenal insufficiency
addisons disease congenital adrenal hyperplasia TB/malignancy bilateral adrenal haemorrhage bilateral adrenalectomy drug induced by rifampicin, phenobarbital, anticoagulants
causes of secondary adrenal insufficiency
lack of ACTH stimulation sheehans syndrome iatrogenic pituitary/hypothalamic disorders pituitary surgery/haemorrhage infection, trauma, tumour of pituitary/hypothalamus cushings disease/syndrome long term glucocorticoid therapy
clinical features of addisons disease
anorexia weight loss skin pigmentation abdominal pain and vomiting diarrhoea fatigue lethargy
what is addisons disease
autoimmiune destruction of the adrenal cortex
what other AA conditions is addisons disease associated with
pernicious anaemia, T1DM, AA thyroid disease
biochemical diagnosis of addisons disease
hyponatraemia and hyperkalaemia hypoglycaemia SST - normal is >250 and post ACTH >550nmol/L high ACTH renin high and aldosterone low
what test is diagnostic to addisons disease
21-OH-Ab is indicative if pt is over 6m
if -ve get CT adrenals for infiltrative disease, malignancy, infection, haemorrhage
management of addisons disease
hydrocortisone - IV if unwell and then oral in divided doses
flurocortisone as aldosterone replacement and monitor BP and K
steroid card
sick day rules
cannot stop suddenly