Adrenal Disorders Flashcards
what does the adrenal cortex produce
glucocorticoids (cortisol)
mineralocorticoids (aldosterone)
androgens
what regulates cortisol/ androgen secretion
pituitary ACTH (which is regulated by hormones made in the hypothalamus)
what controls aldosterone secretion
renin-angiotensin system
and
plasma K+
what is the role of aldosterone (mineralocorticoid)
regulates blood pressure and electrolyte excretion
what long term treatment does adrenal insufficiency need
lifelong replacement of cortisol and aldosterone
what can cause cortisol excess
iatrogenic
due to disorders of pituitary (ACTH dependent)
or adrenal gland (non ACTH dependent)
what can cause aldosterone excess
bilateral adrenal hyperplasia
adrenal adenoma
how is adrenal adenoma treated
surgically
what does aldosterone excess cause
hypertension
how much does a healthy adrenal gland weigh
4 grams in adults
what does the medulla of the adrenal gland produce
catecholamines- adrenalin and noradrenaline
what is corticosterone
a glucocorticoid
what are the zones of the adrenal gland and what do they produce
(from capsule to medulla)
zona glomerulosa (mineralocorticoids)
zona fasciculata (glucocorticoids)
zona reticularis (adrenal androgens)
what is released by the hypothalamus which stimulates the anterior pituitary to produce
corticotropin releasing hormone
what does the hypothalamus release corticotropin releasing hormone in response to
illness, stress, time of day
what does ACTH do
acts on adrenal cortex to release cortisol
what is the HPA axis
hypothalamus - (anterior) pituitary - adrenal cortex
what does cortisol have a negative feedback effect on
both the hypothalamus and the anterior pituitary
what activates the renin-angiotensin system
decreased blood pressure
describe the pathway of the renin angiotensin system (its not that bad chill)
blood pressure falls - kidney produces renin - renin acts on angiotensinogen... - ...forms angiotensin I - angiotensin-converting enzyme turns it into... - angiotensin II which has two actions... - 1. stimulates adrenal gland to secrete aldosterone which.... - causes the kidneys to retain salt (indirectly increases BP) - 2. causes direction vasoconstriction (directly increased BP) = increased blood pressure
what do corticosteroids do
bind to intracellular receptors
receptor ligand complex binds DNA to alter transcription
what are mineralocorticoids and glucocorticoids
corticosteroids
what are the 6 different types of steroid receptors
glucocorticoid mineralocorticoid progestin oestrogen androgen vitamin D
what are the CNS effects of cortisol
mood lability
euphoria/psychosis
decreased libido
what are the effects of cortisol on bone/ connective tissue
accelerates osteoporosis
decreased: serum calcium, collagen formation, wound healing
what are the immunological actions of cortisol
decreased:
- capillary dilation, permeability
- leucocyte migration
- macrophage activity
- inflammatory cytokine production
(reduces immune response)
what are the metabolic effects of cortisol
increased blood sugar
increased lipolysis, central redistribution of lipids
increased proteolysis
what are the circulatory/ renal effects of cortisol
increased cardiac output
increased blood pressure
increased renal blood flow and GFR
what are the clinical uses of corticosteroids
suppress inflammation
suppress immune system (both supraphysiological levels)
replacement treatment (physiological levels)
what diseases are corticosteroids used to treat
allergic diseases: asthma/ anaphylaxis
inflammatory disease: RA, UC, crohns
malignant disease
how can you administer corticosteroids
IV, IM orally
where are mineralocorticoid receptors
kidneys, salivary glands, gut, sweat glands
how does aldosterone affect mineral balance
causes excretion of K+/H+
causes reabsorption of sodium
what is this: 21 year old female ‘unwell’ for few months Weight loss Amenorrhoea Acutely unwell over past 48 hours with vomiting and diarrhoea On examination: Dark skin Dehydrated Hypotensive decreased Na increased K
addisons disease going into addisonian crisis
what should you worry about with hyperkalaemia and hyponatraemia
ADDISONS - IF YOU SUSPECT THIS TREAT IT IMMEDIATELY
what can cause primary adrenal insufficiency
addisons disease
congential adrenal hyperplasia (CAH)
adrenal TB, HIV, malignancy
what are the causes of secondary adrenal insufficiency
lack of ATCH stimulation:
iatrogenic (excess exogenous steroid)
pituitary/ hypothalamic disorder
what is CAH
congenital adrenal hyperplasia- block in production of adrenal corticosteroid, present in neonates or early childhood
milder forms can present in adulthood
what is addisons disease
autoimmune condition causing destruction of the adrenal cortex resulting in adrenal insufficiency
what is the commonest cause of primary adrenal insuffiency
addisons disease
does addisons present early or late in the disease
more than 90% of adrenal cortex destroyed before symptoms start
what other conditions are associated with addisons
autoimmune conditions:
- T1DM
- autoimmune thyroid disease
- pernicious anaemia
what are the clinical features of addisons disease
anorexia, weight loss fatigue. lethargy dizziness and low BP abdo pain, vomiting, diarrhoea increased skin pigmentation
what tests can be done to diagnose adrenal insufficiency
biochem: decreased Na, increased k, hypoglycaemia
short synacthen test: see if cortisol is produced
ACTH levels: increased (causes skin pigementation)
renin/aldosterone levels: increased renin, decreased aldosterone (loss in water and sodium)
adrenal autoantibodies
imaging
what antibodies can be used to investigate pimary adrenal insufficiency
17-OH-progesterone (infants and some childre/adults)
21-OH antibody (all > 6 months old)