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brs (phase 1b) > (endo) hypoadrenalism > Flashcards

(endo) hypoadrenalism Flashcards

1
Q

give three causes of adrenocortical failure

A

1) tuberculous Addison’s disease
2) autoimmune Addison’s disease
3) congenital adrenal hyperplasia

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2
Q

what are the main consequences of adrenocortical failure?

A

mineralocorticoid deficiency
= 1) loss of sodium in the urine (hyponatraemia)
= 2) hyperkalaemia
= 3) hypotension

glucorticoid deficiency
= 1) hypoglycaemia
= 2) increased ACTH resulting in hyperpigmentation

= eventual death due to severe hypotension

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3
Q

explain the relationship between cortisol and insulin

A

cortisol has metabolic effects and so wants to reduce glucose storage and increase glucose bioavailability
= cortisol inhibits insulin

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4
Q

how does cortisol deficiency affect blood glucose compared to excess cortisol?

A

cortisol deficiency = hypoglycaemia

excess cortisol = impaired glucose tolerance/diabetes

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5
Q

what is POMC?

A

pro-opio melanocortin

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6
Q

where is POMC synthesised?

A

synthesised in the pituitary gland

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7
Q

what is POMC cleaved into and why is this significant?

A

cleaved into

  • ACTH
  • aMSH (hormone that stimulates skin pigmentation)
  • endorphins
  • enkephalins
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8
Q

which laboratory tests are carried out to test for Addison’s disease?

A

1) 9am cortisol
2) ACTH

3) short synACTHen test

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9
Q

for a patient with Addison’s disease, what are the expected 9am cortisol & ACTH results?

A

9am cortisol = low

ACTH = high

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10
Q

what is a short synACTHen test and how does it work?

A

synACTHen = synthetic ACTH

following low 9am cortisol and high ACTH, to confirm Addison’s disease, synACTHen is given

= should cause cortisol levels to increase in healthy patients BUT in those w Addison’s, cortisol remains low

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11
Q

for a patient with Addison’s disease, what are the expected short synACTHen test results?

A

following a low 9am cortisol & a high ACTH, if the short synACTHen test is also low
= confirms Addison’s disease

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12
Q

how is a short synACTHen test carried out?

A

measure 9am cortisol

give 250ug synACTHen IM

measure cortisol response

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13
Q

how is adrenal failure treated?

A

1) fludrocortisone (50-100mcg daily)

2) either hydrocortisone (x3 daily 10 - 5 - 2,5) OR prednisolone (3-4mg once daily)

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14
Q

what is fludrocortisone?

A

artificial analogue of aldosterone

= formed by adding fluorine atom to aldosterone

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15
Q

how does fludrocortisone compare to aldosterone?

A

fludorcortisone = longer half life for once daily administration + binds to both MR/GR

aldosterone = too short a half life for OD administration

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16
Q

why does fludrocortisone have a longer half life?

A

cannot be degraded due to fluoride atom

= longer half life

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17
Q

what does fludrocortisone replace as opposed to prednisolone/hydrocortisone?

A

fludrocortisone = replaces aldosterone (mineralocorticoid)

hydrocortisone/predinosolone = replaces cortisol (glucocorticoid)

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18
Q

why does oral hydrocortisone have to be taken thrice a day?

A

has too short a half life for once daily administration

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19
Q

why is prednisolone preferentially given over hydrocortisone to replace cortisol in adrenal failure?

A

prednisolone dose = 3-4mg

hydrocortisone dose total = 15mg

as the hydrocortisone dose is larger, increased risk of diabetes and hypertension = less safe

20
Q

how does prednisolone compare to cortisol?

A

longer half life

more potent

x2.3 binding affinity

21
Q

what is the function of an enteric coating on tablets?

A

1) speeds up intestinal absorption (i.e. keeps drug intact in the gastric environment)
2) reduces side effects

22
Q

what is the most common cause of congenital adrenal hyperplasia?

A

21-hydroxylase deficiency

can be complete or partial

23
Q

in complete 21-hydroxylase deficiency, which hormones are fully absent?

A

aldosterone and cortisol

24
Q

in complete 21-hydroxylase deficiency, which hormones are present in excess and why?

A

sex steroids and testosterone

= lack of 21-hydroxylase results in a build-up of 17-OH progesterone leading to a build-up of sex steroids

25
Q

how long do patients with complete 21-hydroxylase deficiency survive and why?

A

less than 24 hours after birth

= usually have a salt-losing Addisonian crisis due to lack of aldosterone & cortisol

26
Q

how is a salt-losing Addisonian crisis treated in neonates with complate 21-hydroxylase deficiency?

A

administer IV saline

27
Q

how do neonates with complete 21-hydroxylase deficiency present?

A

salt-losing Addisonian crisis

28
Q

why do patients with complete 21-hydroxylase deficieny only present with symptoms AFTER birth?

A

becuase before birth (i.e. in utero), the foetus gets the required steroids (aldosterone/cortisol) across the placenta

29
Q

how do girls with complete 21-hydroxylase deficiency present compared to boys?

A

girls = may have ambiguous genitalia (due to virilisation by excess adrenal testosterone production)

boys =

30
Q

why do girls with complete 21-hydroxylase deficiency have ambiguous genitalia?

A

complete 21-hydroxylase deficiency = excess sex steroids & testosterone

excess adrenal testosterone = virilisation

(!! treat w saline & hydrocortisone !!)

31
Q

what is partial 21-hydroxylase deficiency?

A

when there is just enough 21-hydroxylase to give rise to sufficient amounts of aldosterone and cortisol

(to prevent an adrenal crisis)

= but does lead to excess sex steroids and testosterone

32
Q

in partial 21-hydroxylase deficiency, which hormones are deficient?

A

aldosterone and cortisol

but not deficient to harmful extents

33
Q

in partial 21-hydroxylase deficiency, which hormones are in excess?

A

sex steroids & testosterone

34
Q

at which age do patients with partial 21-hydroxylase deficiency normally present?

A

at any age as they survive longer than those with complete 21-hydroxylase deficiency

35
Q

how do girls with partial 21-hydroxylase deficiency present compared to boys?

A

girls = hirsutism & virilisation

boys = precocious (early) puberty

36
Q

why do boys with partial 21-hydroxylase deficiency undergo precocious puberty?

A

due to adrenal testosterone

37
Q

why does excess ACTH in partial 21-hydroxylase deficiency cause excess adrenal testosterone?

A

in partial 21-hydroxylase deficiency, excess ACTH causes a build-up of 17-OH progesterone
= excess testosterone production

= hirsutism + virilisation in girls // precocious puberty in boys

38
Q

what are the classic signs of partial 21-hydroxylase deficiency?

A

acne

hirsutism

heavy, muscular arms & legs

clitoral enlargement

small breasts

receding hairline/baldness

39
Q

explain the pathophysiology of 11-hydroxylase deficiency

A

with no 11-hydroxylase, both aldosterone + cortisol cannot be synthesised

there is an excess of 11-deoxycorticosterone AND sex steroids/testosterone

11-deoxycorticosterone mimics aldosterone and so in excess, causes hypertension AND hypokalaemia

40
Q

in 11-hydroxylase deficiency, which hormones are deficient?

A

aldosterone and cortisol

41
Q

in 11-hydroxylase deficiency, which hormones are present in excess?

A

sex steroids, testosterone and 11-deoxycorticosterone

42
Q

how do patients with 11-hydroxylase deficiency normally present?

A

excess testosterone = virilisation

excess 11-deoxycorticosterone = hypertension and hypokalaemia

43
Q

why does 11-deoxycorticosterone cause hypertension and hypokalaemia?

A

it mimics the action of aldosterone

44
Q

in 17-hydroxylase deficiency, which hormones are deficient?

A

cortisol and sex steroids/testosterone

45
Q

in 17-hydroxylase deficiency, which hormones are present in excess?

A

aldosterone and 11-deoxycorticosterone

46
Q

how do patients with 17-hydroxylase deficiency present?

A

excess aldosterone = hypertension, hypokalaemia

deficient cortisol = hypoglycaemia, glucocorticoid deficiency

sex steroid deficiency

brs (phase 1b) (71 decks)

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