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Endocrine > Adrenal Physiology and Disorders > Flashcards

Adrenal Physiology and Disorders Flashcards

1
Q

what are the 3 layers of the adrenal cortex from outer to inner?

A

zona glomerulosa
zona fasciculata
zona reticularis

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2
Q

what is secreted by each layer of the adrenal cortex?

A

zona glomerulosa = mineralocorticoids (e.g aldosterone)
zona fasciculata = glucocorticoids (e.g cortisol)
zona reticularis = adrenal androgens (e.g testosterone)

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3
Q

what is present within the adrenal medulla and what is secreted from here?

A

chromaffin cells
medullary veins
splanchnic veins
secretes catecholamines

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4
Q

describe the HPA axis,

A

hypothalamus releases CRH which stimulates pituitary to produce ACTH which stimulates adrenal cortex to produce cortisol

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5
Q

what can have an effect on the activity of the hypothalamus in the HPA axis?

A

illness
stress
time of day
negative feedback from cortisol levels

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6
Q

how are the kidneys involved in blood pressure?

A

kidney senses reduced BP > production of renin > converts angiotensinogen to angiotensin 1 > ACE converts angiotensin 1 to angiotensin 2 > angiotensin 2 acts on adrenals to produce aldosterone which acts back on the kidneys causing water and salt retention > increased blood pressure

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7
Q

how do corticosteroids work?

A

bind intracellular receptor in either the cytoplasm or the nucleus > receptor/ligand complex binds to DNA via phosphorylation > has effects on transcription

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8
Q

what are the 6 classes of steroid receptor?

A 
glucocorticoid
mineralocorticoid
progestin
oestrogen
androgen
vitamin D
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9
Q

how does cortisol affect the cardio/renal system?

A

increased CO, BP, renal blood flow and GFR

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10
Q

give 3 main principles of using cortisol in treatment?

A

suppress inflammation
suppress immune system
replacement therapy

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11
Q

how can cortisol be administered?

A

IV
intramuscular
orally

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12
Q

name 5 disease which cortisol can be used for?

A 
asthma/anaphylaxis
rheumatoid arthritis
ulcerative colitis
crohns
malignancy
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13
Q

what are the functions of aldosterone?

A

sodium/potassium balance (K+ out, Na+ in)
BP regulation
Extracellular volume regulation

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14
Q

where are mineralocorticoid receptors present?

A

kidneys
salivary glands
gut
sweat glands

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15
Q

give an example of a classic presentation of addisons disease

A 
unwell few months
weight loss
amenorrhoea
vomiting/dairrhoea for past 48 hrs
dark skin
dehydrated
hypotensive
high K+, low Na+
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16
Q

what is the commonest cause of primary adrenal insufficiency?

A

addisons disease

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17
Q

what is addisons disease?

A

congenital autoimmune destruction of adrenal cortex

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18
Q

what are the features of addisons disease?

A 
autoantibody positive in 70%
anorexia
weight loss
fatigue/lethargy
dizziness and low BP
abdominal pain
vomiting
diarrhoea
skin pigmentation
associated with other autoimmune diseases (T1DM, autoimmune thyroid disease, pernicious anaemia)
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19
Q

name 2 other causes of primary adrenal insufficiency

A

congenital adrenal hyperplasia (CAH)

adrenal TB/malignancy

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20
Q

name 3 causes of secondary adrenal insufficiency?

A

all due to lack of excess ACTH stimulation
iatrogenic (excess steroid medication)
pituitary/hypothalamic disorders
tumours

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21
Q

what are the clinical features of secondary adrenal insufficiency?

A

similar to addisons apart from

  • skin is pale due to no increased ACTH
  • aldosterone production intact
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22
Q

how is secondary adrenal insufficiency managed?

A

hydrocortisone replacement

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23
Q

how is adrenal insufficiency diagnosed?

A 
biochemistry
short synacthen test
ACTH levels (raised)
renin/aldosterone levels
adrenal antibodies
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24
Q

what does biochemistry show in adrenal insufficiency?

A

decreased Na+
increased K+
hypoglycaemia

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25
Q

describe the short synacthen test

A

measure plasma cortisol before and 30 mins after ACTH injection
normal = before >250nmol/L, after >550nmol/L

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26
Q

what causes skin pigmentation in adrenal insufficiency?

A

raised ACTH levels

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27
Q

describe renin/aldosterone levels in adrenal insufficiency

A

decreased aldosterone

increased renin

28
Q

how is adrenal insufficiency managed?

A 
hydrocortisone and cortisol replacement
- IV first if unwell
- 15-30mg daily
- try to mimic diurinal rhythm
fludrocortisone as aldosterone replacement
education
29
Q

what are the sick day rules for adrenal insufficiency?

A

double dose if at home and unwell
100mg IV followed by 50mg every 6 hours
cannot stop suddenly

30
Q

what are the common presenting features of cushings?

A 
central weight gain
acne
amenorrhoea
hypertension
severe osteoporosis
proximal muscle weakness/myopathy
easy bruising
facial plethora
striae
proximal myopathy
proximal muscle wasting
31
Q

what are the 2 groups of causes of cushings?

A 
ACTH dependant
- pituitary adenoma
- ectopic ACTH
- ectopic CRH
ACTH independent
- adrenal adenoma
- adrenal carcinoma
- nodular hyperplasia
32
Q

how is cushings disease diagnosed?

A

overnight dexamethasone suppression test (mainly)
24hr urinary free cortisol
late night salivary cortisol

33
Q

what is the commonest cause of cushings syndrome?

A

iatrogenic - due to prolonged high dose therapy

  • asthma, RA, IBD, transplant
  • can be oral or inhaled steroids
34
Q

how does steroid therapy affect the adrenal glands?

A

long term use can cause chronic suppression of pituitary ACTH production via negative feedback pituitary and adrenal atrophy

35
Q

what are the implications of the effects of long term steroids on the adrenals?

A

unable to respond to stress
need extra dose when ill/surgical procedure
cannot stop steroids suddenly
gradual withdrawal of steroid therapy if taking over 4-6 weeks

36
Q

name 2 endocrine causes of hypertension?

A

primary aldosteronism

congenital adrenal hyperplasia (CAH)

37
Q

when would you suspect an endocrine cause of hypertension instead of an idiopathic case?

A

young
resistant hypertension
high clinical suspicion

38
Q

what is primary aldosteronism?

A

autonomous production of aldosterone independent of its regulators (angiotensin 2 and potassium)

39
Q

what are the 5 functions of aldosterone?

A 
increases sympathetic outflow
sodium retention
cytokines and ROS synthesis
increases cardiac collagen
altered endothelial function - increased pressure response
40
Q

what are the clinical features of primary aldosteronism?

A

significant hypertension
hypokalaemia
alkalosis

41
Q

what are the 3 subtypes of primary aldosteronism?

A 
bilateral adrenal hyperplasia (most common)
adrenal adenoma (conns syndrome)
rare causes (genetic, unilateral hyperplasia)
42
Q

how is primary aldosteronism diagnosed?

A

ARR-aldosterone to renin ratio

  • if raised, inveastigate further with saline suppression test
  • if plasma aldosterone doesn’t suppress by 50% with 2L of saline = diagnosis of PA
43
Q

how can you confirm the subtype of PA?

A

adrenal CT to demonstrate adenoma

can sometimes do adrenal vein sampling to confirm adenoma is true source of aldosterone excess

44
Q

how is PA managed surgically?

A

unilateral laparoscopic adrenalectomy

  • only if adrenal adenoma
  • cures hypokalaemia and hypertension in most
45
Q

how is PA managed pharmacologically?

A

if bilateral adrenal hyperplasia - use MR antagonists

  • spironolactone
  • eplerenone
46
Q

what is congenital adrenal hyperplasia (CAH)?

A

rare group of autosomal recessive disorders with enzyme defects in the steroid production pathway

47
Q

what is the most common form of CAH?

A

21 alpha hydroxylase deficiency

48
Q

what are the 2 variants of 21 alpha hydroxylase deficiency?

A 
classical
- salt wasting
- simple virilising
non-classical
- hyperandrogenaemia
49
Q

how is 21 alpha hydroxylase deficiency diagnosed?

A

basal 17-OH progesterone

genetic mutation analysis

50
Q

how does classical CAH present?

A 
males
- adrenal insufficiency
- poor weight gain
- biochemical pattern
females
- genital ambiguity
51
Q

how does non-classical CAH present?

A 
hirsute
acne
oligomenorrhoea
precocious puberty
infertility (or sub-fertility)
52
Q

how is CAH managed in children?

A 
quick recognition
glucocorticoid replacement
mineralocorticoid replacement in some
surgical correction
achieve max growth potential
53
Q

how is CAH managed in adults?

A

control androgen excess
restore fertility
avoid steroid over-replacement

54
Q

what is a phaeochromocytoma?

A

neuroendocrine tumour of the adrenal medulla originating from the chromaffin cells

55
Q

what scan is used for phaeochromocytoma?

A

MRI

56
Q

list 6 clues which could indicate a phaeochromocytoma?

A 
labile hypertension
postural hypotension
paroxysmal sweating
heachache
pallor
tachycardia
can have none of the above
57
Q

what is an extra-adrenal phaeochromocytoma known as?

A

paraganglioma

58
Q

list 17 presenting symptoms of phaeochromocytoma

A 
hypertension
postural hypotension
headache
sweating
palpitations
breathlessness
constipation
anxiety
fear
weight loss
flushing
incidental finding on imaging
pallor
family history
bradycardia
tachycardia
pyrexia
59
Q

list 5 biochemical features of phaeochromocytoma?

A 
hyperglycaemia
low potassium
high haematocrit
mild hypercalcaemia
lactic acidosis
60
Q

how is phaeochromocytoma diagnosed?

A 
catecholamines and metabolites in the urine can be first clue
find source
- MRI
- MIBG
- PET scan
61
Q

how is a phaeochromocytoma managed?

A

full alpha and beta blockade (alpha and beta blockers)
fluids/blood replacement
careful anaesthetic assessment
surgery (laprascopy, excision, de-bulking)
chemotherapy if malignant

62
Q

what is included in the follow up from phaeochromocytoma?

A

long term monitoring etc
genetic testing
family testing and investing

63
Q

what 2 conditions is phaeochromocytoma associated with?

A

MEN2

Von-hippel- lindau syndrome

64
Q

what are the metabolic effects of cortisol?

A

increased lipolysis
increased proteolysis
increased blood glucose

65
Q

how does cortisol affect the immune response?

A

dampens the immune response

66
Q

how does cortisol affect bone/connective tissue?

A

accelerates osteoporosis - reduced serum calcium, collagen formation and wound healing

67
Q

how does cortisol affect the CNS?

A

mood lability, euphoria/psychosis, reduced libido

Endocrine (45 decks)

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