Adrenal Gland Physiology & Disorders Flashcards
Where are the adrenal glands found?
on top of each kidney
which hormone is produced in the zona glomerulosa?
aldosterone
which hormone is produced in the zone fasciculata?
cortisol
which hormone is produced in the zone reticularis?
testosterone
where are the hormones that control cortisol & androgen production produced?
hypothalamus & anterior pituitary
what is aldosterone regulated by?
renin-angiotensin system & plasma potassium
what is the renin-angiotensin system activated in response to?
decreased blood pressure
what are the 3 main principles of clinical use of corticosteroids?
suppress inflammation
suppress immune system
replacement treatment
which receptor does aldosterone work on?
mineralocorticoid receptor
where are mineralocorticoid receptors found?
kidneys
salivary glands
gut
sweat glands
what is adrenal insufficiency?
inadequate adrenocortical function
give some examples of primary adrenal insufficiency
addison’s disease
congenital adrenal hyperplasia (CAH)
adrenal TB/malignancy
give some examples of secondary insufficiency
lack of ACTH stimulation
iatrogenic
pituitary/hypothalamic disorders
what is the commonest cause of primary adrenal insufficiency?
Addison’s disease
what is addison’s disease?
autoimmune destruction of adrenal cortex
how do you treat adrenal insufficiency?
hydrocortisone as cortisol replacement
fludrocortisone as aldosterone replacement
how is secondary adrenal insufficiency due to pituitary/hypothalamic disease treated?
surgery or radiotherapy
what is Cushing’s syndrome due to?
excess cortisol secretion
what are the clinical features of cortisol excess?
easy bruising
facial plethora
striae
proximal myopathy
what are the ACTH dependent causes of Cushing’s syndrome?
pituitary adenoma
ectopic ACTH
ectopic CRH
Cushing’s disease
pituitary adenoma
what are the ACTH independent causes of Cushing’s syndrome?
adrenal adenoma
adrenal carcinoma
nodular hyperplasia
what is iatrogenic Cushing’s syndrome due to?
prolonged high dose steroid therapy causing chronic suppression of pituitary ACTH production & adrenal atrophy
what are the implications of adrenal suppression?
unable to respond to stress
need extra doses of steroid when ill/surgical procedure
hypertension + hypokalaemia
primary aldosteronism
primary aldosteronism
autonomous production of aldosterone independent of its regulators
what are the clinical features of primary aldosteronism?
significant hypertension
hypokalaemia
alkalosis
what are the subtypes of primary aldosteronism?
adrenal adenoma
bilateral adrenal hyperplasia
rare causes
what are the rare causes of primary aldosteronism?
genetic mutations
unilateral hyperplasia
what are the surgical ways to manage primary aldosteronism?
laparoscopic adrenalectomy
when would you use surgery to manage primary aldosteronism?
when it is unilateral
when would you use medical ways to manage primary aldosteronism?
in bilateral adrenal hyperplasia
what medication can be used in primary aldosteronism?
MR antagonists
what kind of feedback mechanisms regulates cortisol/androgen secretion?
pituitary ACTH secretion negative feedback mechanism
what does aldosterone regulate?
blood pressure & electrolyte excretion
give an example of congenital adrenal hyperplasia
variants of 21alpha deficiency
what happens in classical 21alpha hydroxyls deficiency
salt-wasting
simple virilising
what happens in non-classical 21alpha hydroxylase deficiency
hyperandrogenaemia
what symptoms are present in males with classical 21alpha hydroxylase deficiency
adrenal insufficiency
poor weight gain
biochemical pattern
what symptoms are present in females in classical 21alpha hydroxylase deficiency
genital ambiguity
what symptoms are found in non-classical 21alpha hydroxylase deficiency
Hirsute Acne Oligomenorrhoea Precocious puberty Infertility or sub-fertility
give 3 patterns that would make suspect phaeochromocytoma
Labile hypertension
Postural hypotension
Paroxysmal sweating, headache, pallor,tachycardia
what happens in pharochomocytoma
Adrenal medulla – phaeochromocytoma
Extra adrenal [sympathetic chain] - paraganglioma
hypertension
when is phaochormocytoma usually diagnosed?
under the age of 5
what is the classical triad of presenting symptoms for phaeochromocytoma
hypertension
sweating
headache
why are phaeochromocytomas known as the 10% tumour
10% malignant 10% extra-adrenal 10% bilateral 10% associated with hyperglycaemia 10% in children 10% familial
what would be found in the urine/plasma of people with phaeochromocytomas?
catecholamines
what drugs are give in phaeochromocytomas?
alpha blockers (phenoxybenzamine) beta blockers (atenolol)
MEN2 is what?
autosomal dominant disease activating mutation in tyrosine kinase receptor
what is MEN2 associated with?
medullary thyroid cancer
parathyroid hyperplasia
bilateral phaeochromocytomas
Von hipple Lindau syndrome is what?
autosomal dominant mutation in VHL gene leading to an accumulation of HIF proteins & stimulation of cellular proliferation
