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
management of adrenal crisis
fluids 100mg hydrocortisone hydrocortisone infusion or 6hr IM cardiac monitor treat cause
true/false - there is a need to treat aldosterone in secondary adrenal insufficiency
false - aldosterone is managed by RAAS
ACTH dependent causes cushings syndrome
pituitary adenoma
Ectopic ACTH
ectopic CRH
ACTH indepedent causes of cushings syndrome
Adrenal adenoma/carcinoma
adrenal hyperplasia
clinical features cushings syndrome
easy bruising thin skin striae proiximal myopathy interscapular fat pad euphoria/altered mood/psychosis thin arms/legs increased abdo fat cataracts osteoporosis menstrual irregularity hypertension oedema decreased libido hirsutism acne virilism
diagnosis of cushings syndrome
overnight dexamethasone suppression test
24 hr urinary free cortisol
late night salivary cortisol
low dose dexamethasone suppression test
how to localise cause of cushings disease biochemically?
identify if ACTH is high/low
if low it is likely adrenal
if high it is likely pituitary/hypothalamic/adrenal
clinical features of primary hyperaldosteronism
hypokalaemia
significant hypertension
alkalosis due to loss of H in urine
causes of primary hyperaldosteronism
adrenal adenoma - conns
bilateral adrenal hyperplasia
genetic mutations
unilateral hyperplasia
diagnosis of primary hyperaldosteronism
measure plasma aldosterone and renin and express as ratio
rasied ratio do a saline suppression test
failure of aldosterone to suppress by >50% with 2L confirms
Adrenal CT/adrenal vein sample
surgical management of primary hyperaldosteronism
for adenoma
unilateral laparoscopic adrenalectomy
only if confirmed by CT and adrenal vein sample
medical management of primary hyperaldosteronidm
bilateral adrenal hyperplasia
use spironolactone of eplerenone
what is the main enzyme deficiency in congenital adrenal hyperplasia
21a-hydroxylase deficiency
diagnosis of congenital adrenal hyperplasia
basal or stimulated 17-OH progesterone
classical presentation of congenital adrenal hyperplasia
adrenal insufficiency
biochemical pattern addisons - low Na and high K
poor weight gain
non-classical presentation of congenital adrenal hyperplasia
hirsutism acne oligomenorrhoea precocious puberty infertility/subinfertility
management of congenital adrenal hyperplasia
recognition, glucocorticoid replacement and mineralocorticoid replacement in some
surgical correction
in adults, control androgen excess and restore fertility
what amino acids are catecholamines derived from?
dopamine, derived from tyrosine
what syndromes are associated with phaeo
neurofibromatosis
MEN2a
von hippel lindau
tuberous sclerosis
classic triad of phaeo? other symptoms?
headache, hypertension, sweating palpitations anxiety and fear constipation flushing incidental FHx
signs of phaeo
hypertension postural hypotension pallor bradycardia/tachycardia pyrexia
signs of complications in phaeo
left ventricle failure myocardial necrosis stroke shock paralytic ileus of bowel
biochemical abnormalities in phaeochromocytoma
hyperglycaemia high haematocrit low potassium mild hypercalcaemia lactic acidosis
10% rules in phaeo?
10% malignant 10% bilateral 10% extra adrenal 10% associated with hyperglycaemia 10% children 10% familial
who to investigate for phaeo
resistant HTN HTN in the young classical symptoms FHx consider in hyperglycaemia and HTN
diagnosis of pheochromocytoma
2x 24hr catecholamine urinary
MRI/CT abdo/body
MIBG
PET
management of pheochromocytoma
full alpha and beta blockade fluid/blood replacement surgical chemo, radiolabelled MIBG biochemical and radiolabelled follow up test for associated genetic conditions/screening family members
how is cushings diagnosed from obesity
thin skin, bruising prox myopathy osteoporosis conjunctival oedema frontal balding in women
what can lead to false positives in cushings diagnosis
alcohol/depression
exogenous steroid
