Flashcards in Adrenal Deck (69):
What are the layers of the adrenal gland?
What are the three zones of the cortex? What do they secrete?
Zona fasciculata- glucocorticoids
Zona reticularis- adrenal androgens
What is contained in the adrenal medulla? What is secreted?
chromaffin cells secrete catecholamines, medullary veins, splanchnic (sympthetic) nerves
What are the corticosteroids made from in the adrenal cortex?
Whatis the end corticosteroid from
a) z. glomerulosa
b) z fasciculata
c) z. reticularis
c) DHEA and androstendione
How is the production of
a) RAAS and plasma K+
b) hypothalamus and ant. pit.
c) hypothalamus and ant. pit
What is the cortisol/androgen axis?
NB, negative feedback
How does the RAAS system work?
Fall in BP
Renin released from kidneys
Turns angiotensinogen to angiotensin 1
ACE turn it to angiotensin 2
Angiotensin 2 causes aldosterone to be released from adrenal
Aldosterone increases salt retention (indirect)
What is the mechinism of action in corticosteroids?
Steroid hormones binds to intracellular receptor
DNA is bound to affect transcription
What are the metabolic affect of cortisol?
increase blood sugar
increased lipolysis (central distribution)
What are the CVS effects of cortisol?
increased renal blood flow and GFR
What are the MSK effects of cortisol?
reduced serum Ca2+
reduced wound healing
What are the immunological effects of cortisol?
reduced capillary permeabilty
What are the main uses of corticosteroids?
suppress immune system
Where are Mineralocorticoid receptors found?
What are the effects of aldosterone?
increased Na+ reabsorption
Regulates ECF volume
What can cause adrenal insuffieciency?
Inadequate adrenal function
What are causes of primary adrenal insufficiency?
Congenital adrenal hyperplasia
What can cause secondary adrenal insufficiency?
lack of ACTH stimmulation
What is the commonest cause of primary adrenal insufficiency?
What is the aetiology of addison's?
Autoimmune destruction of adrenal cortex
Autoantibodies in 70%
Low cortisol levels
How much of the adrenal will be destroyed before symptoms of addison's appear?
With what other conditions is addison's associated?
What are the symptoms of addison's?
Skin pigmentation (ACTH)
What are the diagnositic features of addison's?
increased renin/reduced alsdosterone
What dynamic test would be used to test for addison's? How does it work?
Short SynATCHen test
-measure before and 30 mins after iv ACTH injection
-before >250nmol, after>480 is normal
What is the management for addison's?
Hydrocortisone to replace cortisol( IV if unwell, 15-30mg daily, mimic diuinal rhythm)
Fludrocortisone to replace aldosterone (monitor BP and K)
What education do patients treated for adrenal insufficiency need?
sick day rules
do not stop suddenly
How is secondary adrenal insufficiency characterised?
lack of CRH or ACTH
What is the most common cause of secondary adrenal insufficiency?
(mimcs negative feedback)
How is secondary adrenal insufficiency different to addison's?
Pale skin (no inc ACTH)
Aldosterone intact (no RAAS involvement)
How is secondary adrenal insufficiency treated?
(no need for fludrocortisone)
How is cushing's syndrome defined?
excess cortisol secretion
what is the etiology of cushing's?
What are the symptoms of cushing's?
proximal muscle weakness
What are the adrenal causes of cushing's?
What is the most common cause of Cushing's?
iatrogenic high dose steroids=chronic suppression of ATCH and adrenal atrophy
What is primary aldosteronism?
Autonomus production of aldosterone independent of regulators(angiotensin 2/K)
What are the CVS actions of aldosterone?
increased cardiac collagen
Altered endothelial function
What are the CVS responses to aldosterone?
What are the clinical features of primary aldosteronism?
What are the causes of primary aldosteronism?
adrenal adenoma (Conn's syndrome)
Bilateral hyperplasia (commonest)
Genetic mutation (KCNJ5 channel)
How is primary aldosteronism diagnosed?
1)-measure ARR (aldosterone renin ratio)
->750 then saline suppression test
-failure to suppress saline by 50%=PA
-adrenal vein sample to confirm adenoma s true source
How is primary aldosteronism managed?
Surgical laproscopic adrenalectomy if adenoma.
Spironolactone if bilateral hyperplasia (MR antagonist)
What is congenital adrenal hyperplasia?
defect with enzymes in steroid pathway
What is the most common enzyme deficiency in CAH?
How is CAH diagnosed?
Basal/stimulated 17-OH progesterone levels
How do males with CAH classically present?
Adrenal insufficiency (2-3 weeks)
poor weight gain
Addison's biochemical pattern
How do females with CAH classically present?
What is the non-classical presentation of CAH?
What is the principles of treatment of CAH in children?
Acheive maximum growth potential
What are the principles of treatment in CAH adults?
Control androgen excess
Avoid steroid overreplacement
What is the weight of an adrenal gland in healthy adults?
What is phaeochromocytoma?
rare tumour of adrenal medulla
Why do adrenals look brown in phaeochromocytoma?
chromaffin cells reduce chrome salts to metal chromium
Why is it important to diagnose phaeochromocytoma?
What are the symptoms of phaeochromocytoma?
Triad: hypertension (50%paroxysmal), headache, sweating
What are the signs of phaeochromocytoma?
postrual hypotension (50%)
What are the biochemical abnormalities in phaeochromocytoma?
Who should be investigated for phaeochromocytoma?
family memebers with syndromes
<50 yrs patient with HT
HT and Hyperglycaemia
How can phaeochromocytoma be confirmed?
confirm catecholamine excess
Urine catecholamine samples 2x24hr
How can you identify the source of catecholamine excess in phaeochromocytoma?
How is phaeochromocytoma treated?
alpha and beta blockade
fluid+/- blood replacement
total excision where possible
chemotherapy if malignant
What conditions are associated with phaeochromocytoma?
Multiple endocrine neoplasia 2
Succinate dehydrogenase mutations
What is MEN2?
mutation of tyrosine kinase receptor
associated:MTC, parathyroid hyperplasia, bilateral phaeochromocytoma
What is Von Hippel Lindau syndrome?
SDH genes stabilise HIF1-a
What are the signs of neurofibromatosis?
Cafe au lait patches
What is the apperance of phaeochromocytoma?
Zellballen (cells form nests)